Download Virology

Virology
John J. Kopchick, Ph.D.
What happens after a virus infects the body?
Colored slide: H-2
Major Families of Animal
Viruses
DNA Containing Viruses
RNA containing Viruses
Major Families of Animal Viruses
DNA Containing Viruses
Poxviridae
Chorodopoxvirinae
Genus
Orthopoxvirus
Subfamily
Host
Variola major
Humans
Monkeypox
Monkey, humans
Cowpox
Cattle, humans
Symptoms in
Humans
Smallpox
Smallpox-like
disease
Vesicular eruption
of the skin
Major Families of Animal Viruses
DNA Containing Viruses
Herpesviridae
Alphaherpesvirinae
Genus Simplexvirus
Subfamily
Host
Symptoms in Humans
Human herpesvirus 1
(herpes simplex virus type
1 (HSV 1))
Humans
Infections of the
oropharynx, eye, skin, and
genitalia; generalized
systemic disease; severe
and generally fatal
encephalitis
Human herpesvirus 2
(herpes simplex virus type
2 (HSV 2))
Humans
Primary genital infections
Cercopithecine herpesvirus
1 (B virus)
Humans, monkeys
Fatal encephalitis
Herpesvirus
Members of the family herpesviridae are found in a wide range of host
systems. To date, at least seven different species are known to infect man,
including herpes simplex virus (HSV); cytomegalovirus (CMV), varicella
zoster (VZV); and Epstein Barr virus (EBV).
Herpesviruses have an envelope surrounding an
icosahedral capsid, approximately 100nm in
diameter, which contains the dsDNA genome.
When the envelope breaks and collapses away
from the capsid, negatively stained virions have
a typical "fried-egg" appearance.
Major Families of Animal Viruses
DNA Containing Viruses
Adenoviridae
Genus
Mastadenovirus
Human adenoviruses
41 serotypes
Subfamily
Host
Symptoms in
Humans
Subgroup A
Serotypes:12, 18 &
31
Humans
Regularly isolated from
feces of apparently
healthy individuals; high
incidence of antibodies
Subgroup B
Serotypes:
3,7,11,14,16,21,34,
35
Humans
Acute respiratory
disease (also 4);
pharyngitis (3,7); acute
hemorrhagic cystitis in
children (11, 12); low
incidence of antibodies
Adenovirus
Adenoviruses are non-enveloped icosahedral particles.
The capsid is built up from 252 capsomers (T=25), of which 240 are
hexavalent and 12 (situated at the apices) are pentavalent.
A "penton fibre"projects from each apex.
Adenoviruses that infect humans are usually mild pathogens, and can cause
respiratory illness or conjunctivitis (so-called "pink eye"), but under
laboratory conditions some human strains can transform cells in culture.
Major Families of Animal Viruses
DNA Containing Viruses
Papovaviridae
Human Papilloma Viruses
(HPV) 1-34
Genus Papillomavirus
Subfamily
Host
Symptoms in Humans
HPV 1&4
Humans
Planter warts
HPV 2&4
Humans
Common warts (verruca
vulgaris)
HPV 3&10
Humans
Flat warts (verruca plana)
and/or epidermodysplasia
verruciformis (EV)
HPV
5,8,9,12,14,15,17,19-25
Humans
Red-brown 9macular)
plaques of EV (potential
for malignancy in light
exposed areas)
Papillomavirus
Many types of papillomavirus cause
benign skin tumours (warts) in their
natural hosts. These warts often
regress spontaneously, but human
genital warts (tumours caused by
specific types of papillomavirus,
particularly types 16 and 18) regularly
become malignant if they persist for a
sufficiently long time.
Papillomavirus particles are approximately 55nm in
diameter.
The capsid is composed of 72 morphological units, or
capsomers, arranged on the surface of a T=7
icosahedron. The capsomers located at each of the
12 vertices, are pentavalent (i.e. each is surrounded
by five adjacent capsomers), and the other 60
capsomers are hexavalent (each adjacent to six
capsomers).
Major Families of Animal Viruses
DNA Containing Viruses
Hepadnaviridae
Hepatitis B virus
(HBV)
Subfamily
Host
Hepatitis B Virus
Humans
Symptoms in
Humans
Acute and chronic
hepatitis; cirrhosis;
hepatocellular
carcinoma; immune
complex disease;
polyarteritis;
glomerulonephritis;
infantile papular
acrodermatitis; aplastic
anemia
Hepatitis B Virus
Hepatitis B virus causes both acute and chronic liver infections in man. An unusual
feature is the prolonged viraemia, lasting for up to several months in acute
infections and for many years (even for life) in chronic infections.
A diagrammatic representation of the hepatitis B virion and the surface
antigen components
.
Virions are 42nm in diameter and possess an isometric nucleocapsid or
"core" of 27nm in diameter, surrounded by an outer coat approximately
4nm thick. The protein of the virion coat is termed "surface antigen" or
HBsAg. It is sometimes extended as a tubular tail on one side of the virus
particle. The surface antigen is generally produced in vast excess, and is
found in the blood of infected individuals in the form of filamentous and
spherical particles. Filamentous particles are identical to the virion "tails" they vary in length and have a mean diameter of about 22nm. They
sometimes display regular, non-helical transverse striations.
Hepatitis B virus
RNA Containing Viruses
Major Families of Animal Viruses
RNA Containing Viruses
Picornaviridae
Genus Enterovirus
Human
enteroviruses
Subfamily
Host
Poliovirus
3 serotypes
Humans, monkey
Coxsackle virus A
23 serotype (124; A23 is ECHO
virus 9)
Humans, mouse
Symptoms in
Humans
Poliomyelitis
Primarily general
striated muscle
damage; herpangina,
aseptic meningitis;
paralysis; the common
cold syndrome
Enteroviruses
(Picornaviruses)
The family Picornaviridae is one of the largest of the viral families, and contains
some of the smallest (pico) RNA viruses known to infect man.
The family is divided into five genera: enteroviruses, rhinoviruses (cause of the
common cold), cardioviruses, apthoviruses and hepatoviruses (cause of hepatitis A).
The enterovirus genus is so-called because these viruses generally replicate in the
intestine. The most important enterovirus pathogens include poliovirus and
Coxsackie A and B viruses.
Virions are icosahedral and about
30nm in diameter. Each capsid is
composed of 60 copies of 4 structural
proteins - VP1, VP2, and VP3 are
exposed on the virion surface,
while VP4 lies buried in close
association with the RNA core.
Immunogenic sites are located
on the exposed external parts of
the capsid. The electron micrograph
illustrates an immune complex of
enterovirus particles linked by
antibody molecules.
Major Families of Animal Viruses
RNA Containing Viruses
Reoviridae
Genus
Orthoreovirus
Subfamily
Host
Mammalian reoviruses
3 serotypes
Humans, other
mammals
Colorado tick fever
virus
Ticks, Mammals
Symptoms in
Humans
Pathogenicity not
established
Encephalitis
Genus Rotavirus
Human rotavirus
Humans
Acute infantile
gastroenteritis
Rotavirus
Rotaviruses infect the lining of the intestine and cause diarrhoea, especially in children.
Rotavirus particles are approximately 75nm in diameter. They have icosahedral symmetry and
particles possess two concentric protein shells, or capsids. The term "rota", meaning wheel, is
derived from the appearance of the complete double-capsid particle when viewed by negative
staining in a position where the 5-fold axis of symmetry is acentric. Apparent spoke-like
components are then visible on one side of the virus particle.
A double-capsid particle is shown on the left, and the single (inner) capsid on its right.
The arrangement of capsomers on the inner capsid gives the appearance of a
lattice - 5 capsomers surround a space at each apex (5-fold axis)
Major Families of Animal Viruses
RNA Containing Viruses
Orthomyxoviridae
Genus Influenzavirus
Subfamily
Host
Influenza virus type A
Human subtypes
A0 (H1N1) 1933-1947 &
1977-present
A1 (H1N1) 1947-1957
A2 (H2N2) 1957-1968
(Asian)
A3 (H3N2) 1968-present
(Hong Kong)
Humans
Swine influenze virus
Swine
Symptoms in Humans
Acute respiratory disease
Acute respiratory disease
Acute respiratory disease
Acute respiratory disease
Acute respiratory disease
Influenza virus
Influenza virus (an Orthomyxovirus) is responsible for acute upper respiratory
disease, usually accompanied by fever and myalgia.
Virions are usually roughly
spherical and about 200nm in
diameter.
The envelope contains rigid
"spikes" of haemagglutinin and
neuraminidase which form a
characteristic halo of
projections around negatively
stained virus particles.
The viral genome is composed of eight segments of ssRNA.
The helical ribonucleo-protein is not often seen,
but occasional particles show evidence of internal helical
components
Major Families of Animal Viruses
RNA Containing Viruses
Retroviridae
Genus
Oncornavirus C
Human T-cell
leukemia/lymphoma
virus
Subfamily
HTLV-I
HTLV-II
Host
Symptoms in
Humans
Humans
Isolated from patients
with cutaneou T-cell
lymphomas and adult Tcell leukemia
Humans
Isolated from a T-cell
line established from a
patient with a variant
of hairy cell leukemia
Major Families of Animal Viruses
RNA Containing Viruses
Retroviridae, continued
Lentivirinae
Subfamily
Host
Human immunodeficiency
virus (HIV) also known
as human T-cell
leukemia virus III
(HTLV-III) or
lymphadenopathy
associated virus (LAV)
Humans
Symptoms in
Humans
Acquired immune
deficiency syndrome
(AIDS)
Major Families of Animal Viruses
DNA Containing Viruses
Poxviridae, Continued
Chorodopoxvirinae
Genus Parapoxvirus
Subfamily
Host
Symptoms in
Humans
Orf (contagious
pustular dermatitis
CPD)
Sheep, goats,
humans
Nodules on hands
Pseudocowpos
(milkers nodule
virus)
Cattle,humans
Nodules on hands
Major Families of Animal Viruses
DNA Containing Viruses
Poxviridae, Continued
Ungrouped
Subfamily
Host
Symptoms in
Humans
Molluscum
contagiosum
Humans
Benign epidermal
tumors
Tanapoxvirus
Humans
Short febrile
illness, pocklike
skin lesions
Yaba monkey tumor
virus
Monkeys, humans
Benign epidermal
tumors that soon
regress
Major Families of Animal Viruses
DNA Containing Viruses
Herpesviridae, continued
Alphaherpesvirinae
Genus Simplexvirus
Subfamily
Host
Human herpesvirus 3
(varicella-zoster virus
(VZV))
Humans
Symptoms in Humans
Chickenpox, herpes
zoster
Betaherpesvirinae
Genus Cytomegalovirus
Human herpesvirus 5
(human
cytomegaloviruses
(HCMV))
Humans
Jaundice,
hepatosplenomegaly,
brain damage, death
Major Families of Animal Viruses
DNA Containing Viruses
Herpesviridae, continued
Gammaherpesvirina
e
Genus
Lymphocryptovirus
Subfamily
Host
Human herpesvirus
4
(Epstein-Barr virus
(EBV))
Humans
Symptoms in
Humans
Infectious
mononucleosis,
Burkitt’s lymphoma,
nasopharyngeal
carcinoma
Major Families of Animal Viruses
DNA Containing Viruses
Adenoviridae, continued
Subfamily
Host
Symptoms in Humans
Subgroup C
Serotypes:1,2,5,6
Humans
Mild infections of the
respiratory tract,
especially in infants and
children; pneumonia in
infants and young children
(1,2,3,& 7); pertussislike
syndrome in infants and
young children (5)
Subgroup D
Serotypes:
8,9,10,13,15,17,19,20,22
-30, 32,33,36-39
Humans
Epidemic
keratoconjunctivitis
(8,11,19,37); low incidence
of antibodies
Subgroup E
Serotypes: 4
Humans
Acute respiratory disease
Major Families of Animal Viruses
DNA Containing Viruses
Adenoviridae, continued
Subfamily
Host
Subgroup F
Serotypes: 40
Humans
Acute gastrointestinal
disease in children
Subgroup G
Humans
Acute gastrointestinal
disease in children
Serotypes: 41
Symptoms in
Humans
Major Families of Animal Viruses
DNA Containing Viruses
Papovaviridae, continued
Subfamily
Host
Symptoms in
Humans
HPV 6 & 11
Humans
Anogential warts
(condylomata acminata),
otolaryngeal warts
HPV 7
Humans
Meat handler’s warts
HPV 2&4
Humans
Common warts (verruca
vulgaris)
HPV 13
Humans
Oral focal hyperplasia
HPV 16,18,31,33
and 34
Humans
Gential tract cancers,
including invasive
carcinomas of the
cervix
Major Families of Animal Viruses
DNA Containing Viruses
Papovaviridae, continued
Human Papilloma Viruses
(HPV) 1-34
Genus Polyomavirus
Subfamily
Host
Symptoms in Humans
BK virus
Humans
Isolated from the urine of
renal transplant patients
JC virus
Humans
Isolated from the brains
of patients with
progressive multifocal
leukoencephalopathy
Lymphotrophic papovavirus
(LPV)
African green monkey,
Humans (?)
Multiples only in monkey
and human B lymphoblasts.
About 30 percent of
humans have antibody
against it.
Major Families of Animal Viruses
DNA Containing Viruses
Parvoviridae
Genus Parvovirus
Subfamily
Host
Symptoms in Humans
Parvovirus-like agent
(PLVA) Strain B19
Humans
Erythemia infectiosum
(fifth disease); linked to
aplastic crisis in hemolytic
anemia/sickle cell anemia
Lu-111
Humans
No known disease
Genus Dependovirus Adenoassociated virus (AAV)
Serotypes 1,2,3,5
Humans
Antibodies very prevalent;
no known symptoms
Major Families of Animal Viruses
RNA Containing Viruses
Picornaviridae, continued
Genus Enterovirus
Human enteroviruses
Subfamily
Host
Symptoms in Humans
Coxsackle virus B
6 serotypes
Humans, mouse
Primarily fatty tissue and
CNS damage; pleurodynia
(Bornholm disease); aseptic
meningitis; paralysis;
severe systemic illness of
newborns
ECHOviruses (enteric
cytopathogenic human
orphan) 32 serotypes
Humans
Paralysis, diarrhea, aseptic
meningitis
Human enterovirus 72
(hepatitis A virus)
Humans
Infectious hepatitis,
jaundice
Major Families of Animal Viruses
RNA Containing Viruses
Picornaviridae, continued
Genus Cardiovirus
Subfamily
Host
Encephalomyocarditi
s virus (EMC) (Several
Primarily mouse,
various other
species, including
humans
very closely related
viruses including
mengovirus, ME virus,
EMC virus, MM virus
and Columbia SK virus)
Symptoms in
Humans
Mild febrile illness
Genus Rhinovirus
Human rhinoviruses
113 serotypes
Humans
Common cold,
bronchitis, croup,
bronchopheumonia
Major Families of Animal Viruses
RNA Containing Viruses
Togaviridae
Genus Alphavirus
(mosquito-borne)
Subfamily
Host
Symptoms in
Humans
Eastern equine
encephalitis (EEE)
Birds
Encephalitis: Frequently
Fatal
Semliki forest virus
Monkeys
Encephalitis (rare)
Sindbis
Monkeys
Fever, rash, arthritis
Chikungunya
Monkeys
Myositis-arthritis
Ross river virus
Mammals
Fever, rash, arthralgia
Venezuelan equine
encephalitis (VEE)
Rodents
Encephalitis
Western equine
encephalitis (WEE)
Birds
Encephalitis
Major Families of Animal Viruses
RNA Containing Viruses
Togaviridae, continued
Genus Rubivirus
Subfamily
Host
Rubella virus
Humans
Symptoms in
Humans
Severs deformities of
fetuses in first
trimester of pregnancy
Major Families of Animal Viruses
RNA Containing Viruses
Flaviviridae
Mosquito-borne
Subfamily
Host
Symptoms in Humans
Yellow Fever
Monkey
Hemorrhagic fever,
hepatitis, nephritis, often
fatal
Dengue virus
4 serotypes
Humans
Fever, arthralgia, rash
West Nile fever
Birds
Fever, arthralgia, rash
St. Louis encephalitis
Birds
Encephalitis
Japanese encephalitis
Birds
Encephalitis; frequently
fatal
Murray Valley encephalitis
Birds
Encephalitis
Major Families of Animal Viruses
RNA Containing Viruses
Flaviviridae,continued
Tick-borne
Subfamily
Host
Symptoms in Humans
Central European tickborne encephalitis
(biphasic
meningoencephalitis)
Rodents, hedgehog
Encephalitis
Far Eastern tick-borne
encephalitis (Russian
spring-summer
encephalitis, RSSE)
Rodents
Encephalitis
Kyasanur forest virus
Rodents
Hemorrhagic fever
Louping III
Sheep
Encephalitis
Powassan
Rodents
Encephalitis
Omsk hemorrhagic fever
virus
Mammals
Hemorrhagic fever
Major Families of Animal Viruses
RNA Containing Viruses
Coronaviridae
Antigenic Group I
Subfamily
Host
Human coronavirus
Strain HCV-229E
Humans
Symptoms in
Humans
Upper respiratory
disease
Antigenic Group II
Human coronavirus
Strain HCV-oc43
Humans
Upper respiratory
disease
Major Families of Animal Viruses
RNA Containing Viruses
Rhabdoviridae
Genus Lyssavirus
Subfamily
Host
Rabies virus
All warm-blooded
animals
Symptoms in
Humans
Encephalitis, almost
invariably fatal
Filoviridae
Subfamily
Host
Symptoms in
Humans
Marbug virus
Humans
Acute hemorrhagic
fever; frequently fatal
Ebola virus
Humans
Acute hemorrhagic
fever; frequently fatal
Major Families of Animal Viruses
RNA Containing Viruses
Paramyxoviridae
Genus Paramyxoviridae
Subfamily
Host
Symptoms in Humans
Parainfluenza virus
type 1 Sendai virus
(hemagglutinating virus of
Japan [HVJ])
Humans, pig, mouse
Croup, common cold
syndrome
HA-2 (hemadsorption virus)
Humans
Parainfluenza viruses types
2-5 Numerous strands
including HA-1, SV5
Humans and other animals
Mumps
Human
Mild respiratory disease
Respiratory tract
infections
Parotitis, orchitis,
meningoencephalitis
Paramyxoviruses
The family of Paramyxoviridae contains viruses that induce a wide
range of distinct clinical illnesses in humans:These include measles virus, which in rare instances is followed by
subacute sclerosing panencephalitis (SSPE); mumps virus, which has
symptoms of parotitis, orchitis and encephalitis, and the parainfluenza
viruses which are respiratory pathogens .
Virions are enveloped and enclose a helical
nucleocapsid containing single-stranded
RNA. Most virions are roughly spherical
(about 200nm in diameter) but they can
be much larger and more pleomorphic.
The virus envelope is a lipid bilayer,
studded with virus encoded glycoproteins
which have properties of haemagglutination
and fusion (the F protein).
Major Families of Animal Viruses
RNA Containing Viruses
Paramyxoviridae, continued
Genus Morbillivirus
Subfamily
Host
Measles
Humans
Symptoms in
Humans
Measles; chronic
degeneration of the
central nervous system
(SSPE)
Genus Pneumovirus
Respiratory syncytial
virus (RSV)
Humans
Pneumonia and
bronchiolitis in infants
and children, common
cold syndrome
Major Families of Animal Viruses
RNA Containing Viruses
Orthomyxoviridae, continued
Genus Influenzavirus
Subfamily
Host
Equine subtypes
Influenza virus type B
Human subtypes
B0 1940-1945
B1 1945-1955
B2 1962-1964
B3 1962-present (Taiwan)
Humans
Influenza virus type C
(possible separate genus)
Humans
Symptoms in Humans
Acute
Acute
Acute
Acute
respiratory
respiratory
respiratory
respiratory
disease
disease
disease
disease
Respiratory disease
Major Families of Animal Viruses
RNA Containing Viruses
Bunyaviridae
Genus Bunyavirus
(16 serogroups)
Subfamily
Host
Symptoms in Humans
Bunyamwera
Mammals
Fever, rash
California encephalitis group
including La Crosse, Lumbo
and snowshoe hare virus
Mammals
Encephalitis
Genus Phlebovirus
Sandfly fever virus
Sandfly, mammals
Rift Valley fever virus
Humans, sheep, cattle
Facial erythema
Fever, arthralgia, retinitis
Major Families of Animal Viruses
RNA Containing Viruses
Bunyaviridae, continued
Genus Nairovirus
Subfamily
Host
Crimean-Congo
hemorrhagic fever
(CCHF)
Mammals
Unclassified Bunyavirus
Hantaan virus
(Korean hemorrhagic
fever)
Rodents
Symptoms in
Humans
Hemorrhagic fever
Hemorrhagic fever with
renal syndrome
Major Families of Animal Viruses
RNA Containing Viruses
Arenaviridae
Subfamily
Host
Symptoms in
Humans
Lymphocytic
choroiomeningitis virus
(LCM)
Mouse, Humans
Tacaribe virus complex
Several viruses including
Argentinian (Junin)
hemorrhagic fever &
Bolivian (Machupo)
hemorrhagic fever
Rodents, Humans
Hemorrhagic fever;
frequently fatal
Lassa virus
Rodents
Hemorrhagic fever;
frequently fatal
Latent infection in mice;
may produce fatal
meningitis in other species,
including humans
Retroviruses
Life Cycle
HIV
AIDs
Retrovirus – General Picture
www.openthefuture.com/images/retrovirus.jpeg
Three Genes: GAG = GROUP ANTIGEN
POL = POLYMERASE
ENV = ENVELOPE
HIV Structure
17
24
7
6
2 copies
RNA
10 –Protease
32 – Int
66/51 –RT
http://student.bmj.com/back_issues/1198/data/1198ed1.htm
Retroviral Life Cycle
Reverse Transcription
Viral
Viruses and Cancer
• No oncogenes noted, yet these
viruses cause leukemias and
lymphomas
• Their names were once RNA tumor
viruses and RNA leukemia viruses
LTR
LTR
Proviral DNA inserts “randomly”.
Long terminal repeats (LTR) containing 3’5’ sequences act
as transcriptional “Promoters”.
Since these LTRs are identical and since they are located
at each end of the proviral DNA, they can promote viral
gene expression as well as “adjacent” gene expression.
Growth Factors
Receptors
Intracellular Signalling molecules
Transcription Factors
Proto-oncogenes and oncogenes
related to cellular receptors and
signal transduction intermediates
• Receptors
– EGF (epidermal growth factor)
– Neu (neuroblastoma)
• Signal Transduction Intermediates
– Insulin signaling intermediates
– “ras”
Oncogene Receptor
Proteins
•
Creation of oncogenes from
proto-oncogenes that encode
cell-surface receptors. In the
example diagrammed here, the
neu-oncogene arises from a
mutation that alters a single
amino acid (valine to
glutamine) in the
transmembrane region,
somehow making the protein
constitutively active as a
kinase. In the other example,
the receptor is for EGF; the
oncogene arises by loss of the
coding region for the EGFbinding domain.
From Molecular and Cell Biology, Lodish, et al., 1995
Erbitux
HIV (Retrovirus) – General Picture
www.openthefuture.com/images/retrovirus.jpeg
Retroviral Life Cycle
HIV Structure
17
24
7
6
2 copies
RNA
10 – Protease
32 – Int
66/51 – RT
http://student.bmj.com/back_issues/1198/data/1198ed1.htm
www.stanford.edu/.../2005gongishmail/HIV.html
HIV Life Cycle
Attachment
CD4 Normal Function
•
CD4 is a co-receptor that assists the
T cell receptor (TCR) with an
antigen presenting cell. Using its
portion that resides inside the T
cell, CD4 amplifies the signal
generated by the TCR by recruiting
an enzyme known as the tyrosine
kinase, lck, which is essential for
activating many molecules
involved in the signaling cascade of
an activated T cell. CD4 also
interacts directly with MHC Class
II molecules on the surface of the
antigen-presenting cell using its
extracellular domain.
CD4 (cluster of differentiation 4) is a gycoprotein found on the surface
of immune cells such as T helper cells, monocytes, macrophages, and
dendritic cells. It was discovered in the late 1970s and was originally
known as leu-3 and T4 (after the OKT4 monoclonal antibody that
reacted with it) before being named CD4 in 1984. In humans, the CD4
protein is encoded by the CD4 gene.
CD4+ T helper cells are WBCs that are an essential part of the human
immune system. They are often referred to as CD4 cells, T-helper cells
or T4 cells. They are called helper cells because one of their main roles
is to send signals to other types of immune cells, including CD8 killer
cells. CD4 cells send the signal and CD8 cells destroy and kill the
infection or virus. If CD4 cells become depleted, for example in
untreated HIV infection, or following immune suppression prior to a
transplant, the body is left vulnerable to a wide range of infections that
it would otherwise have been able to fight.
Wikipedia Free Encyclopedia
Attachment – up close
gp120
gp41
CD4
CCR5
Emini, E. & Koff, W.C. Developing an AIDS vaccine; Need, Uncertainly, Hope.
Science, 304: 1913, 2004
HIV Life Cycle
From the following article:
HIV drug development: the next 25 years
Charles Flexner
Nature Reviews Drug Discovery 6, 959966 (December 2007)
HIV Tropism
HIV tropism refers to the cell type that the human immunodeficiency virus (HIV) infects and
replicates in. HIV tropism of a patient's virus is measured by the Trofile assay.
HIV can infect a variety of cells such as CD4+ helper T-cells and macrophages that express the CD4
molecule on their surface. HIV-1 entry to macrophages and T helper cells is mediated not only through
interaction of the virion envelope glycoproteins (gp120) with the CD4 molecule on the target cells but
also with its chemokine co-receptors.
Macrophage (M-tropic) strains of HIV-1, or non-syncitia-inducing strains (NSI) use the betachemokine receptor CCR5 for entry and are thus able to replicate in macrophages and CD4+ T-cells.
These strains are now called R5 viruses. The normal ligands for this receptor, RANTES, macrophage
inflammatory protein (MIP)-1-beta and MIP-1-alpha, are able to suppress HIV-1 infection in vitro.
This CCR5 coreceptor is used by almost all primary HIV-1 isolates regardless of viral genetic subtype.
T-tropic isolates, or syncitia-inducing (SI) strains replicate in primary CD4+ T-cells as well as in
macrophages and use the alpha-chemokine receptor, CSCR4, for entry. These strains are now called
X4 viruses. The alpha-chemokine, SDF-1, a ligand for CSCR4, suppresses replication of T-tropic HIV1 isolates. It does this by down regulating the expression of CXCR4 on the surface of these cells.
Viruses that use only the CCR5 receptor are termed R5, those that only use CXCR4 are termed X4,
and those that use both, X4R5. However, the use of coreceptor alone does not explain viral tropism,
as not all R5 viruses are able to use CCR5 on macrophages for a productive infection.[1]
CD4+ T cell
Penetration
Penetration – con’t.
Reverse transcription
Integration
Transcription
Translation of viral mRNAs into viral
precursor proteins
Envelope Precursor Protein Processing
Gag and Gag-Pol Precursor Assembly
with viral RNA
Viral Assembly – con’t.
Virus release and maturation
Viral Protease
Polypeptide
cleavage
160
Cellular
protease
Polypeptide cleavage
Viral
Protease
Polypeptide cleavage
Viral
Protease
Polypeptide cleavage
Viral ‘Env’ proteins
(gp120, gp41)
Viral ‘Gag’ Proteins
(p17, p24, p9, p6)
Viral ‘Pol’ proteins
(Reverse Transcriptase, RNAse,
Integrase, Protease)
A human immunodeficiency viral particle is seen budding from the infected cell surface
at the top, with a complete viral particle at bottom in this high magnification electron
micrograph.
Human immunodeficiency virus, viral particles are seen
at low magnification adjacent to
the cell surface in this electron micrograph.
Human immunodeficiency viral particles are seen at medium magnification in this
electron micrograph. Note the central core and the outer envelope.
HIV Life Cycle
with Drug Targets
Atripla (Sustiva/Viread/Emtriva) – Approved July 11th, 2006
DESCRIPTION
REYATAZ® (atazanavir sulfate) is an azapeptide
inhibitor of HIV-1 protease.
The chemical name for atazanavir sulfate is
(3S,8S,9S,12S )-3,12-Bis(1,1-dimethylethyl)-8hydroxy-4,11-dioxo-9-(phenylmethyl)6-[[4-(2-pyridinyl)phenyl] methyl]2,5,6,10,13-pentaazatetradecanedioic acid
dimethyl ester, sulfate (1:1). Its
molecular formula is C38H52N6O7•H2SO4,
which corresponds to a molecular weight of
802.9 (sulfuric acid salt). The free base
molecular weight is 704.9. Atazanavir sulfate
has the following structural formula:
Mechanism of Action
Atazanavir (ATV) is an azapeptide HIV-1 protease
inhibitor (PI). The compound selectively inhibits
the virus-specific processing
of viral Gag and Gag-Pol polyproteins in HIV-1
infected cells, thus preventing formation of
mature virions.
Reyataz is manufactured by Bristol-Myers
Squibb and was approved for the treatment
of HIV by the U.S. FDA in 2006.
DESCRIPTION
FUZEON (enfuvirtide) is an
inhibitor of the fusion of HIV-1
with CD4+ cells. Enfuvirtide is
a linear
36-amino acid synthetic
peptide with the N-terminus
acetylated and the C-terminus
is a carboxamide.
It is composed of naturally
occurring L-amino acid
residues.
Mechanism of Action
Enfuvirtide interferes with
the entry of HIV-1 into cells
by inhibiting fusion of viral
and cellular
membranes. Enfuvirtide binds
to the first heptad-repeat
(HR1) in the gp41 subunit of
the viral
envelope glycoprotein and
prevents the conformational
changes required for the
fusion of viral
and cellular membranes.
2006
NYSE | BMY 24.79 | +0.23 | 1:30 PM EDT | 17 Jul
2006
Top Story
FDA Approves
ATRIPLA™ (efavirenz 600 mg/ emtricitabine 200 mg/
tenofovir disoproxil fumarate 300 mg), The First Once-Daily
Single Tablet Regimen For Adults With HIV-1 Infection
Princeton, NJ and Foster City, CA (July 12, 2006) -- Bristol-Myers
Squibb Company (NYSE: BMY) and Gilead Sciences, Inc.
(Nasdaq: GILD) today announced the U.S. Food and Drug
Administration (FDA) has granted approval of ATRIPLA™
(efavirenz 600 mg/ emtricitabine 200 mg/ tenofovir disoproxil
fumarate 300 mg) for the treatment of HIV-1 infection in adults.
ATRIPLA is the first-ever once-daily single tablet regimen (STR)
for HIV intended as a stand-alone therapy or in combination
with other antiretrovirals. The product combines SUSTIVA®
(efavirenz), manufactured by Bristol-Myers Squibb, and
Truvada® (emtricitabine and tenofovir disoproxil fumarate),
manufactured by Gilead Sciences. Truvada itself is a fixed-dose
product that contains two of Gilead's anti-HIV medications,
Viread® (tenofovir disoproxil fumarate) and Emtriva®
(emtricitabine), in a single once-daily tablet for use as part of
combination therapy. ATRIPLA will be available in the United
States within seven business days.
Maraviroc – CCR5 blocker
•
Pfizer Gets the Nod from FDA for First-in-Class HIV Drug
Aug 7 2007, 12:53 PM EST
•
FDA has given Pfizer the go-ahead for its first-in-class HIV medication, maraviroc. The
company expects that the drug, which will be sold under the trade name Selzentry, will be
available in the U.S. by the middle of September.
•
•
•
•
•
After receiving a unanimous vote of support from an FDA advisory committee in April, the
agency stalled by sending Pfizer an approvable letter in June. The final sanction of the
drug drove Pfizer’s shares up 60 cents, or 2.6%, to $24.11 at 4:01 p.m. in New York Stock
Exchange composite trading.
Pfizer is awaiting approval from the EMEA and is submitting marketing applications to
other regulatory bodies. On June 20, an EMEA advisory committee vouched in favor of
maraviroc, which will be sold in the EU as Celsentri.
Rather than fighting HIV inside white blood cells, maraviroc prevents the virus from
entering uninfected cells by blocking the predominant route of entry, the CCR5 coreceptor. Among patients who have previously received HIV medications, approximately
50% to 60% have circulating CCR5-tropic HIV-1, according to the FDA.
•
The agency granted accelerated approval to Selzentry in combination with other
antiretroviral drugs in adults with CCR5-tropic HIV-1 who have been treated with other
HIV medications and who have evidence of elevated levels of HIV in their blood. A
diagnostic test is required to confirm whether a patient is infected with CCR5-tropic
HIV-1, which is also known as R5 virus.
•
Longer-term data will be required before the FDA can consider traditional approval for
Selzentry, Pfizer notes.
Integrase Inhibitor
•
Merck & Co. Gets the Green Light for HIV Treatment in EU
Dec 21 2007, 12:38 PM EST
•
The European Union Commission approved Merck & Co. first-in-class HIV therapy
Isentress® (Raltegravir). The drug will be marketed for use in combination with
other antiretroviral products against HIV-1 infection in treatment-experienced
adults with evidence of HIV-1 replication despite ongoing antiretroviral therapy
(ART).
•
The commission’s decision is applicable to the 27 member states of the EU.
Separate national licenses will also be issued in European Economic Area member
states Iceland and Norway, according to Merck, also known as Merck Sharp &
Dohme (MSD) in some countries.
•
Isentress is already sanctioned in North America. MSD says that it is also
moving forward with filings in other countries around the world.
•
Isentress is the first approved integrase inhibitor. It inhibits the insertion of
the HIV DNA into human DNA by the integrase enzyme. Inhibiting integrase
from performing this essential function blocks the ability of the virus to
replicate and infect new cells. Other drugs target the other two enzymes
critical to HIV replication, protease and reverse transcriptase. Pfizer’s
Maraviroc, on the other hand, which received FDA approval in August, blocks the
CCR5 co-receptor.
“Raltegravir is an important new advancement in the treatment of HIV because
it is the first therapy in a new class of drugs that attacks the virus in a
completely different way from other available medicines,” notes Ken Frazier, evp
and president, global human health, Merck.
•
Atripla (Sustiva/Viread/Emtriva) – Approved July 11th, 2006
Drugs in Development Nature News
Nature Reviews Drug Discovery 6, 258-259 (April 2007)
Approved
HIV Life Cycle
Group 1
Group 3
Group 2
www.stanford.edu/.../2005gongishmail/HIV.html
HIV Life Cycle
Other HIV Proteins
• TAT - Transactivator of HIV gene expression
•
•
•
•
•
One of two essential viral regulatory factor
Two forms; 72 aa and 86 aa.
Nucleus/nucleolus location
Binds TAR cis element in viral RNA
Activates transcription; one means is by
preventing the 5’ LTR polyadenylation signal from
causing premature termination of transcription.
• First eukaryotic transcription factor known to
interact with RNA rather than DNA
Other HIV Proteins
• REV
–
–
–
–
The second necessary regulatory HIV protein
19kDA phospho-protein
Localized in nucleus/nucleolus and cytoplasm
Binds to RRE in viral RNAs and promotes viral
nuclear export and stability.
– One of first proteins produced in infected cell
– Encoded by doubly spliced viral mRNA
– Helps viral mRNA to get out of nucleus.
Other HIV Proteins
• VIF - viral infectivity factor
– Basic protein, 23 kDa.
– Promotes infectivity but not production of viral
particles
– In absense of VIF, viral particles are defective
– Cytoplasmic protein
– Molecular mechanism unknown
Other HIV Proteins
• VPR; VPU; NEF; VPX
• Now, What about AIDS??
CDC Classification System for HIV-Infected Adults
and Adolescents
Clinical Categories
CD4 Cell Categories
Asymptomatic,
Acute HIV, or PGL
A.
B. Symptomatic
C. AIDS-Indicator
Conditions*
Conditions, #* not A
or C
(1) ≥500 cells/µL
A1
B1
C1
(2) 200-499 cells/µL
A2
B2
C2
(3) <200 cells/µL
A3
B3
C3
Key to abbreviations:
CDC = U.S. Centers for Disease Control and Prevention;
PGL = persistent generalized lymphadenopathy.
# For symptomatic conditions, see Table 2 .
* For AIDS-indicator conditions, see Table 3 .
HIV Classification:
CDC and WHO Staging Systems
July 2006
Table 2.
CDC Classification System:
Category B Symptomatic Conditions
•
Category B symptomatic conditions are defined as symptomatic conditions occurring in an
HIV-infected adolescent or adult that meet at least 1 of the following criteria:
–
–
•
•
•
•
•
•
•
•
•
•
•
a) They are attributed to HIV infection or indicate a defect in cell-mediated immunity.
b) They are considered to have a clinical course or management that is complicated by HIV infection.
Examples include, but are not limited to, the following:
Bacillary angiomatosis
Oropharyngeal candidiasis (thrush)
Vulvovaginal candidiasis, persistent or resistant
Pelvic inflammatory disease (PID)
Cervical dysplasia (moderate or severe)/cervical carcinoma in situ
Hairy leukoplakia, oral
Idiopathic thrombocytopenic purpura
Constitutional symptoms, such as fever (>38.5°C) or diarrhea lasting >1 month
Peripheral neuropathy
Herpes zoster (shingles), involving ≥2 episodes or ≥1 dermatome
Table 3. CDC Classification System:
Category C
AIDS-Indicator Conditions
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Bacterial pneumonia, recurrent (≥2 episodes in 12 months)
Candidiasis of the bronchi, trachea, or lungs
Candidiasis, esophageal
Cervical carcinoma, invasive, confirmed by biopsy
Coccidioidomycosis, disseminated or extrapulmonary
Cryptococcosis, extrapulmonary
Cryptosporidiosis, chronic intestinal (>1-month duration)
Cytomegalovirus disease (other than liver, spleen, or nodes)
Encephalopathy, HIV-related
Herpes simplex: chronic ulcers (>1-month duration), or bronchitis, pneumonitis, or esophagitis
Histoplasmosis, disseminated or extrapulmonary
Isosporiasis, chronic intestinal (>1-month duration)
Kaposi sarcoma
Lymphoma, Burkitt, immunoblastic, or primary central nervous system
Mycobacterium avium complex (MAC) or M kansasii , disseminated or extrapulmonary
Mycobacterium tuberculosis , pulmonary or extrapulmonary
Mycobacterium , other species or unidentified species, disseminated or extrapulmonary
Pneumocystis jiroveci (formerly carinii ) pneumonia (PCP)
Progressive multifocal leukoencephalopathy (PML)
Salmonella septicemia, recurrent (nontyphoid)
Toxoplasmosis of brain
Wasting syndrome due to HIV (involuntary weight loss >10% of baseline body weight) associated with
either chronic diarrhea (≥2 loose stools per day ≥1 month) or chronic weakness and documented fever
≥1 month
Replication
The replication process is catalyzed by an
enzyme; DNA dependent DNA polymerase
2-deoxy Thymidine and AZT
2-deoxythymidine
Zidovudine or azidothymidine (AZT)
Dideoxynucleoside HIV Drugs
AZT – Retrovir
ddI – videx
ddC – Hivid
d4T – Zerit
3TC - Epivar
Dideoxynucleotides
HIV Life Cycle
Colored slide: H-91
Links to videos.
Hiv Life
Cycle
NRTI
NNRTI
http://www.youtube.com/watch?v=RO8
MP3wMvqg
http://www.youtube.com/watch?v=qY
UnDzDO-Ic
http://www.youtube.com/watch?v=RUUyd5bE
9vQ&NR=1
Protease Inhibitors
http://www.youtube.com/watch?v=yYZgFn
dtfzc&NR=1
HAART – Highly Active Anti Retroviral Therapy
Definitions
• Tumors - “Un-controlled” cellular
growth that arises with great
frequency especially in older animals
and humans.
• Transformation - The process
whereby “normal” cells become
altered or transformed and acquire
the ability to form tumors.
Definition: Cancer
Cancer: An abnormal growth of cells which tend to proliferate in an uncontrolled way and, in some
cases, to metastasize (spread).
•
Cancer is not one disease. It is a group of more than 100 different and distinctive diseases.
•
Cancer can involve any tissue of the body and have many different forms in each body area. Most
cancers are named for the type of cell or organ in which they start. If a cancer spreads
(metastasizes), the new tumor bears the same name as the original (primary) tumor.
•
•
•
•
The frequency of a particular cancer may depend on gender. While skin cancer is the most common
type of malignancy for both men and women, the second most common type in men is prostate cancer
and in women, breast cancer.
Cancer frequency does not equate to cancer mortality. Skin cancers are often curable. Lung cancer is
the leading cause of death from cancer for both men and women in the United States today.
•
Benign tumors are NOT cancer; malignant tumors are cancer. Cancer is NOT contagious.
•
Cancer is the Latin word for crab. The ancients used the word to mean a malignancy, doubtless
because of the crab-like tenacity a malignant tumor sometimes seems to show in grasping the tissues
it invades. Cancer may also be called malignancy, a malignant tumor, or a neoplasm (literally, a new
growth).
Cancer Description, con’t.
Cancer (medical term: malignant neoplasm) s a class of diseases in which a group of cells
display uncontrolled growth (cell division beyond the normal limits), invasion (intrusion on
and destruction of adjacent tissues), and sometimes metastasis (spread to other locations
in the body via lymph or blood).
These three malignant properties of cancers differentiate them from beign tumors, which
are self-limited, do not invade or metastasize. Most cancers form a tumor but some, like
leukemia, do not. The branch of medicine concerned with the study, diagnosis, treatment,
and prevention of cancer is oncology.
Cancer may affect people at all ages, even fetuses but the risk for most varieties
increases with age. Cancer causes about 13% of all deaths. According to the American
Cancer Society, 7.6 million people died from cancer in the world during 2007. Cancers can
affect all animals.
Nearly all cancers are caused by abnormalities in the genetic material of the transformed
cells. These abnormalities may be due to the effects of carcinogens, such as tobacco
smoke, radiation, chemicals, or infectious agents. Other cancer-promoting genetic
abnormalities may be randomly acquired through errors in DNA replication, or are
inherited, and thus present in all cells from birth. The heritability of cancers are usually
affected by complex interactions between carcinogens and the host's genome. New
aspects of the genetics of cancer pathogenesis, such as DNA methylation, and microRNAs
are increasingly recognized as important.
Definitions - Oncology
• Oncology - The scientific study of tumors.
• Oncogene - Cancer causing gene; derived
from Greek word meaning a bulk or mass.
• Proto-oncogenes - Cellular genes know to
be progenitors of oncogenes.
• Oncoproteins - Protein products encoded
by oncogenes that transform cells from
normal to malignant.
How many genes are involved in
breast cancer?
•
Next year marks the 10th anniversary of the mapping of the breast-ovarian cancer
susceptibility gene BRCA1 to chromosome 17 [1], and the identification of the TP53
gene as the cause of the Li-Fraumeni syndrome [2]. As a result of these discoveries, and
the subsequent discovery of other breast cancer susceptibility genes, notably BRCA2
[3], inherited susceptibility has risen from relative obscurity to have a central role in
breast cancer research. Understanding the biological mechanisms that underlie the
susceptibility genes has become a major research activity, and of course mutation
testing is now a major part of clinical genetics practice, with the prospects for
improved prevention and treatment of the disease in women at high risk. Thus, it is
natural to ask whether there are any more genes to find, what their characteristics
might be and how we might go about finding them.
•
Of the five genes that are, beyond any reasonable doubt, breast cancer predisposition
genes, the BRCA1 and BRCA2 genes are the most important numerically (Table 1).
Mutations in these genes, which cause high risks of breast and ovarian cancer, account
for almost all the multiple case breast-ovarian cancer families, and probably around 2%
of breast cancer cases overall [4,5]. Germline mutations in the TP53 gene predispose to
a spectrum of cancers known as the Li-Fraumeni syndrome, including childhood sarcomas
and brain tumours, as well as early-onset breast cancer [2]; and germline mutations in
the PTEN gene are responsible for Cowdens syndrome, of which breast cancer is a
major feature [6]. Mutations in a fifth gene, the androgen receptor gene, are known to
pre-dispose to breast cancer in men [7].
Reference to previous slide.
•
•
•
•
•
•
•
•
Breast Cancer Res. 1999; 1(1): 14–17.
Published online 1999 August 23. doi: 10.1186/bcr6.
PMCID: PMC138504
Copyright © 1999 Current Science Ltd
How many more breast cancer predisposition genes are there?
Douglas F Easton1 1Cancer Research Campaign (CRC) Genetic Epidemiology
Unit, Strangeways Research Laboratories, Worts Causeway, Cambridge, UK.
Douglas F Easton: [email protected]
Received July 16, 1999; Accepted July 22, 1999.
Colored slide: H-72