Download Herpes viruses

Dr Vidya Pai

Naked ,icosahedral capsid viruses are-
i.
Parvo
ii.
Papova &
iii.
Adeno viruses

Enveloped viruses are -
i.
Hepadna
ii.
Herpes
iii. Pox virus - Largest & with complex symmetry.
Herpes virus
 Group
has about eight important pathogens.
 Are ubiquitous and cause disease in plants and
animals and are of economic importance.
 Cause spectrum of diseases
 Have ability for latency
 Have ability for periodic activation
 Also a vesicular rash is common except in CMV &
EB viral diseases.
 These
are distinguished by
a. Antigenicity
b. Location of lesion
 Lesion
of HSV-1 above waist, HSV – 2 below
waist [abnormal behavior – may change
location]
 HSV-1
–
Acute gingivo stomatitis.
Recurrent herpes labialis – Cold sores.
Keratoconjunctivitis
Encephalitis.
 HSV-2
- Genital herpes
Neonatal herpes
Aseptic meningitis

Morphology and structure of both are same.

Differentiation is by
i. Restriction endonuclease patterns of the genomic DNA.
ii. Using types specific monoclonal antisera
iii. On chick embryo CAM type 2 strains form
larger pocks resembling variola.
iv. Types 2 strains replicate well in chick embryo
fibroblast cells, while type 1 strains do so poorly.
v. The infectivity of type 2 is more temperature sensitive
than that of type 1.
vi. Type 2 strains are more neurovirulent in laboratory
animals than type 1.
vii. Type 2 strains are more resistant to antiviral agents
like IUDR and cytarabine in culture.

Humans are natural host for both, but experimental
infections can be transmitted into rabbits and mice.

enveloped virion – 200 nm.

Envelope is derived from the modified host cell nuclear
membrane.

Envelope has 8 nm long surface spikes.

Icosahedral capsid has 152 capsomers.

In between envelope and capsid is the amorphous
tegument [structural viral proteins].

Linear ds DNA

HSV-1 by saliva i.e., direct contact.

HSV-2 by sexual contact.

The virus is easily inactivated at room temp. and drying,
aerosol and Fomite spread are unusual means of
transmission.

Special situation – oro- genital sex and auto inoculation is
not uncommon mode - HSV-2 in oral cavity – 10-20%.
HSV-1 in infection of genital tract.

Transmission occurs actively if there is active lesion.

It also occurs in asymptomatic cases where virus shedding is
present.

Spread of HSV – 1 infection from oral secretions to other skin
areas is an occupational hazard – dentists, respiratory care
unit staff, wrestlers.

Laboratory acquired, Nosocomial out breaks in hospital and
neonatal nurseries can occur.

Most primary HSV-1 is thought to occur in child hood because
antibody is present in most of us.

HSV-2 – occurs during phase of sexual activity – antibody
seen during that age.
 Initial
site of infection – i.e. skin or mucous
membrane, replication occurs, Migrate in neuron –
latent in sensory ganglion cells
 HSV-1
– trigeminal ganglia
 HSV-2
- lumbar and sacral ganglia
 Precise
mechanism unknown – may be by lysogeny.
Induced by sunlight hormonal changes, trauma, stress,
fever, U-V light.

Migrate down the neuron and replication in skin
causing lesions.

Skin lesion – vesicle – [serous fluid with virus
particles, cell debris].

When rupture - vesicle release virions and can be
transmitted to others

Multinucleated giant cell [can be seen by Tzanck smear
– fluid with toluidine blue] are typical at the base of
lesion.

Also there is type specific immunity which can give
some cross protection.

But immunity is incomplete because reinfection and
reactivation can occur in presence of circulating IgG.

CMI is important for defense because if suppressed
reactivation and severe disease. .
1.
Gingivostomatitis – children, fever, irritability and
vesicular lesion in the mouth. These heal by 2-3
weeks. But children may be asymptomatic also.
2.
Herpes labialis – milder recurrent form of HSV
Infection.
 Also called fever blisters, cold sores – crops of
vesicles seen.
 Recurs
frequently at the same site as previous one.
Gingivo-stomatitis
Herpes labialis
Corneal ulcer, lesion of conjunctival epithelium
scarring and blindness following recurrence.
4.
5.
Encephalitis– Temporal lobe involved frequently,
high mortality severe neurologic sequelae with
those who survive.
Herpetic whitlow - Pustular lesions of finger or
hand. Usually in medical personal as a result of
contact with patients lesion.
6. Disseminated – Oesophagitis, pneumonia usually
seen in immunocompromised because of defect in
the T cell.
 Causes
 1.
primary and recurrent infection.
Genital – painful vesicular lesion – in both
sexes.
-Lesion in genital, anal area
-Primary disease is severe and protracted than in
recurrent disease
-There is inguinal lymphadenopathy & fever
 Asymptomatic
disease also seen –
In men prostate, urethra
In female cervix.
 They
 Also
are source for others.
many people have antibody to HSV-2 but no
history of disease.
2. Neonatal herpes – Contact of vesicular lesions in
birth canal during delivery.
 Some
cases have no visible lesions but still
asymptomatic shedding of virus by mother can
occur leading to child being infected.
 Lesion
in child – asymptomatic or mild local lesions
or severe encephalitis or generalized disease.
 Caesarian
section advised if lesions are seen and
positive viral culture of mother.
 Both
HSV-1 & 2 can cause severe neonatal infection
after birth through carriers handling the child.
 It
does not cause congenital abnormalities alone.
Aseptic meningitis – by HSV-2 is usually mild, self
limiting and with few sequelae following recovery.
1. Isolation of virus – Fibroblast cell culture
 CPE
observed in 1-3 days
 Followed
by fluorescent Ab staining of infected
cells or detection of virus specific glycoprotein
by ELISA.
 2.
Rapid diagnosis –Giemsa or Toluidine blue -multinucleated giant cell with Cowdry type A
inclusion body. PAP stain also for HSV-2.
3. Rapid diagnosis of encephalitis – Fluorescent Ab
staining of brain biopsy material, because culture is
not useful as virus is rarely recovered.
 DNA
detection in CSF has replaced brain biopsy.
 MRI
scan can detect encephalitis.
 CSF
shows lymphocytic pleocytosis, protein increase
and sugar is normal.
4. Serology – Neutralization test used in diagnosis of
primary infection
 ELISA,
CF - by observation of increase in Ab titer by
paired sera examination.
 Not
useful in recurrent infection because adults
already have circulating Ig and recurrences rarely
cause rise in Ab titer.
1.
Acyclovir [zovirax] – encephalitis and systemic disease of HSV-1
recurrent or primary genital herpes, neonatal herpes by HSV-2

But mutants resistant to acyclovir seen
Foscarnet used in these cases.
2. Trifluridine topical [a nucleoside analogue] used for eye infection.
3. Penciclovir for orolabial, recurrent infection and in immunocompetent.

No drug treatment prevents recurrences

No effect on latent state.

Prophylactic acyclovir may help to suppress recurrences.
VARICELLAZOSTER VIRUS
Disease:
Varicella–chickenpox
–primary disease
Zoster – Shingles –
recurrent form.
VZV structurally and morphologically similar but
antigenically different from HSV.
 There
is a single serotype- same virus causes both
type of disease.
 Humans
are the natural host.
 Replicative
cycle – same as HSV.
 By
respiratory droplets, direct contact with lesion.
 Highly
contagious
disease
of
children–
population has Ab by 10 years of age.
 World
wide in distribution.
90%
 VZV
infect mucosa of upper respiratory tract.
 Enter
blood  skin
 Vesicular
rash [typical] having multinucleated giant
cell and intranuclear inclusions in cells of base of
lesion.
 Recovery
 Latency
in dorsal root ganglion.
 Later
in life especially if decrease in CMI, trauma
etc. – reactivation
 leads
to vesicular skin lesion and also nerve pain.
 Immunity
 But
following Varicella is life long
Zoster can occur despite varicellar immunity.
 Zoster
can also occur once but frequency increases
with age because of waning immunity.
 Varicella
 Brief
– incubation period 14-21 days.
prodromal period of fever and malaise.
 Followed
 Crops
by papulo vesicular rash
of them on trunk and later spreading to
head and extremities [centripetal rash]
 Leads
to papules, vesicles, pustules, crusting with
severe itching.

Usually varicella is mild in children but severe in adults.

In adults- severe symptoms, profuse rash, which may be
sometimes hemorrhagic and bullous.

Complications in aged are varicella pneumonia and
encephalitis, myocarditis, nephritis, cerebellar ataxia,
meningitis, erythema multiforme.

Reyes syndrome – encephalopathy, liver degeneration is
associated with VZV, influenza B virus especially with
children given aspirin [unknown pathogenesis].
painful vesicles along the course of a sensory
nerve of the head or trunk.
 Pain
lasts for weeks and post zoster neuralgia
can occur and is very debilitating requiring
ganglion surgery often as treatment.
 It
can also cause Bell’s palsy - Zoster of facial
nerve.
 If
there is tympanic involvement and Bell’s palsy -it
is called Ramsay Hunt Syndrome.
 In
immunocompromised – systemic dissemination –
pneumonia which is life threatening.

Clinically chicken pox or shingles can be diagnosed

Presumptively by Tzanck smear – similar to HSV.

Definitive diagnosis by isolation in cell culture and use
of specific antiserum to identify growth inside the cell
line.

Rise in titer of antibody [paired sera] useful for
diagnosis of chickenpox.

Not useful for zoster because antibody already present.
Normal persons no need of antiviral therapy.

In immunocompromised Acyclovir can be given in
systemic disease.

Foscarnet for resistant mutants.

In zoster for accelerating healing of lesion – Acyclovir,
famciclovir, valacyclovir cure – but these do not cure
latent state.

No effect on post zoster neuralgia which usually effects
old people.

Acyclovir in immunocompromised useful.

VZIG – high titer of antibody virus – passive immunization.

VZV virus – live attenuated [varivax] prevent varicella – oka
strain by Takahashi.

One dose for 1-12 yrs,Teenagers 2 doses.

For zoster not useful
Diseases – Cytomegalic
inclusion disease [especially
congenital abnormalities]
in neonates.

Pneumonia and other
diseases in
immunocompromised

Heterophile negative
mononucleosis in immuno
competent.
Properties – Structurally & morphologically
similar to HSV.
 Antigenically
 Humans
different, single serotype.
are natural host, animal strains do
not infect.
 Giant
cells are formed hence the name
Replication – Similar to HSV.
 Unique
feature – some of the immediate
early proteins are translated from mRNAs
brought into the infected cell from the
original virion and not from the mRNA
synthesized in the newly infected cell.

Variety of modes.

Early in life – across placenta, within birth canal,
mothers milk

Common mode – saliva in children

Later in life – sexually – present both in semen and
cervical secretion

Blood transfusion and organ transplants.

World wide in distribution – 80% of adults have antibody.
 Cytomegalic
inclusion disease.
 Multinucleated
inclusions.
giant cells and ‘owl’s eye’

Many organs effected – congenital abnormalities results.

Commonly fetal infection is due to mother who
contracts the virus during 1st trimester and also this
mother has no antibodies to neutralize the virus.

Infection in children and adults – asymptomatic except
in immunocompromised.

CMV enters latent state also in leucocytes and
reactivated if decrease in CMI.

It can persist in kidneys for years.

CMV reactivation from cervical cells leads to infection
during birth

CMV causes immunosuppression by inhibiting T cells.

Host defense is circulating antibody and CMI – this is
important because its suppression leads to systemic
disease.

Approximately 20% of infected infants – cytomegalic
inclusion disease – microcephaly, seizures, deafness,
jaundice and purpura.

Hepatosplenomegaly is very common.

Cytomegalic inclusion
disease is one of the
leading causes of
mental retardation

Infected infants can
continue to excrete
CMV, especially in the
urine, for several
years.

In immunocompetent adults, CMV can cause heterophile
negative mononucleosis, which is characterized by
fever, lethargy and the presence of abnormal
lymphoctyes in peripheral blood smears.

Systemic CMV infections, especially pneumonitis and
hepatitis, occur in a high proportion of
immunosuppressed patients, eg. those with renal and
bone marrow transplants.
 In
AIDS patients, CMV commonly infects the
intestinal tract and causes intractable diarrhea.
 CMV
also causes retinitis in AIDS patients, which can
lead to blindness.
The usual approach- culturing in special
tubes called shell vials
Later
immunofluorescent antibody used
to detect growth
Diagnosis
In
in 72 hours.
cell cultures virus remains cell
associated and CPE is slow [1-2 weeks].
 Immunofluorescence
with specific antibody
will detect the virus in cultures.
 If
available, PCR-based assays that detect
viral nucleic acids are also useful.

Others - fluorescent antibody and histologic staining of
inclusion bodies in giant cells - urine and in tissue [samples].

The inclusion bodies are intranuclear and have an oval owls
eye shape.

A 4 fold or greater rise in antibody titre is also diagnostic.

PCR based assays for CMV DNA or RNA in tissue or body fluids,
such as spinal fluid, are also very useful.

IgM in serum by ELISA – can also be employed.
Treatment Ganciclovir
[Cytovene], Cidofovir [Vistide],
Fomiversin [Vitravene] is used in the treatment of
CMV retinitis and pneumonia in patients with AIDS.
 Fomiversin
– antisense DNA approved for intraocular
treatment of CMV retinitis [latest drug and the only
antisense DNA approved for human use].
 Foscarnet
 CMV
is also good but many side effect.
is resistant to acyclovir.
Prevention No
vaccine
 Ganciclovir
can suppress progressive retinitis in AIDS
– so prophylactic drug.
 Isolation
 Blood
of infants shedding virus in urine
transfusion to new born or to anyone should
be CMV negative.
 As
for as possible CMV antibody negative donors or
organs should be used to transplant to antibody
negative individuals requiring transplantation.
Named after Epstein and Barr
 They
observed the virus under electron microscope
from cultures of lymphoblasts derived from
Burkitt’s lymphoma.
 It
is implicated in Burkitt’s lymphoma, other B cell
lymphomas, nasopharyngeal carcinoma.
 It
is also associated with a whitish nonmalignant
lesion on the tongue called hairy leukoplakia –
especially in AIDS patients.
 Commonly
it causes infectious mononucleosis [IM]
or kissing disease or glandular fever commonly in
teenagers.
Important properties EBV
is structurally and morphologically identical to
other herpesvirus but is antigenically different.
 Has
a VCA antigen - it is used most often in
diagnostic tests.
 The
early antigens [EA] produced prior to DNA
systhesis.
 EB
DNA – nuclear antigen located in the nucleus
bound to chromosomes.
 All
these help in diagnosis.
Others – Lymphocyte determined membrane
antigen.
Viral membrane antigen.
 Neutralizing
activity is directed against viral
membrane antigen.
 EBV
replicates in the nasopharyngeal epithelial
cells, salivary glands [Parotids]
 Lyses
the cells and are released in the saliva
 When
B cell is infiltrated it is also a target and
gets infected.
 Here
latency is seen – forms a hybrid with B cell
 Multiple
copies of EBV DNA is found in cytoplasm of
infected B cell.
 Some
of these genes are transcribed and only a
subset of them is translated into proteins.
 The
latently infected cells can also be activated – B
cell then can secrete IgM.
 It
has glycoprotein envelope gp350/220 which
mediates attachment to CD21 receptor on
susceptible cell – C3d receptor of the cell.
 Humans
are natural host.
 Infection
in oropharynx [epithelium or lymphoid tissue?]
– Spread to blood – Infect B lymphocyte – Cyto T cell
attack infected B lymphocytes.
 The
T cells are atypical lymphocytes[Downey cells]
seen in blood smear.
 EBV
can remain latent in B lymphocytes, few copies of
EBV DNA integrated to cell genome.
 Many
copies of circular EBV DNA also found in the
cytoplasm.
 Immune
response to EBV – first IgM antibody to VCA.
 IgG
antibody to VCA follows and persists for life.
 IgM
useful for diagnosis of acute infection
 IgG
– reveals prior infections.
 Life
long immunity to second episodes of IM is
based on antibody to the viral membrane antigen.
 Non
specific - Heterophile antibodies are found.
 Heterophile
antibody of IM agglutinate sheep or
horse RBC in laboratory [Forssman antibody is
human serum can cross react with these antigens
 So
it is removed by adsorption with guinea pig
kidney extract prior to agglutination].
 These
antibody do not react with any component of
EB virus.
 Likely
explanation is EBV infection modifies a cell
membrane constituent so that it be comes antigenic
and induces heterophile antibodies.
 Usually
heterophile antibody disappears within 6
months after recovery.
 These
are not specific for EBV as they can also be
found in Hep B and serum sickness.

Most shedding of virus occur in the oral cavity. So contact
with saliva – kissing, contaminated eating utensils transmit.

Commonest world wide

During childhood most infection are asymptomatic

In adolescents it causes infectious mononucleosis or
glandular fever.

In immunocompromised it has oncogenic potential and
causes Burkitts lymphoma, naso pharyngeal carcinoma
[China], thymic carcinoma [USA].

15-25 age group

Incubation period 4-7 weeks.

Sore throat exudative tonsillitis, generalised
lymphadenopathy, fever, malaise headache, sweating,
fatigue, G-I discomfort.

Sometimes liver, spleen enlarged

A maculopapular rash follows treatment with ampicillin

This is due to immune complexes with antibody to
Ampicillin.
 So
contraindicated.
 Lasts
for 2-3 weeks
 Complication
– Guillain Barre syndrome, Bells Palsy,
meningo encephalitis, transverse myelitis,
hemolytic anemia, thrombocytopenia, carditis,
nephritis, pneumonia and splenic rupture.
 1.
Burkitt’s lymphoma – malignant B cell lymphoma
seen in equatorial Africa, New Guinea where malaria
is hyperendemic.
 EBV is usually acquired early in life.
 Malaria is the co-factor which potentiates the
oncogenic potential of virus from B cell.
 EBV genome DNA has been found as an episome in the
African Burkitt’s, lymphoma cells.
 The
cells themselves do not produce virions.
 But
if grown, in vitro virions are produced.
2. Nasopharyngeal carinoma –
Racial and geographical.
 Seen in Chinese, Eskimos, Green landers.
 Virions have been isolated form the malignant
epithelial cells.
3. B cell lymphoma – Immunodeficient patients eg.
patients, transplant recepients may develop
lymphomas.
HIV
these
4. Oral hairy leukoplakia – In HIV patients, capsid of EBV
seen in affected tissues.
5. Thymic carcinoma – seen in USA.

Hematological approach – absolute lymphocytosis
10,000 – 20,000 cells/ cumm

Mainly lymphocytes and monocytes 20-30% or more
‘atypical lymphs’.

These are large pleomorphic blasts with deeply
basophillic vacuolated cytoplasm and globulated nuclei.

These are present in blood for 2 weeks or months [these
are cyto - Tcell]
2.
Immunological approach – Infectious mononucleosis
is accompanied by heterophile aggluttinins.

These are IgM elicited by EBV infection.

These appear during acute phase in about 90% of
patient sera.

Peak levels in 2 weeks after onset.

Titer decrease rapidly by 4th week and not persists after
3 months.
 Agglutination
of sheep or horse red cells by patients
serum adsorbed with guinea pig kidney cell to
remove Forssman antibody is basis of test.
 Tube
 Not
agglutination test – Paul Bunnel test.
useful to detect prior infection.
 Monospot
test – Commercial more sensitive, more
specific, cheaper than tube agglutination test.
Treatment: No
EB vaccine.
 Acyclovir
 It
reduces EBV shedding during administration.
does not prevent immortalisation of EBV- B cells.
 No
use in lymphomas or IM
 Adoptive
transfer of EBV reactive T cell is promising
treatment
 For
EBV associated lympho proliferative disease
 Malaria
eradication associated with decreased
incidence of Burkitt’s lymphoma.
 Mass
screening in China for IgA antibody to EBVAg
was useful in early diagnosis of nasopharyngeal
carcinoma.
 20%
of Chinese with elevated IgA were biopsied and
found to have carcinoma.
Other Herpes viruses
 Human
HSV-6 – Same features of HSV.
 Infects
dividing CD4 + T lymphocytes.
 Infected
cell show ballooning with nuclear or
cytoplasmic or both inclusions.
 Macrophages
 Isolation
are also infected so act as reservoir.
from saliva.
 Culture
done on transformed B lymphocytes, NK
cell, Glial cells, fibroblasts, epithelial cells.
 Infection
is asymptomatic – in immunocompromised
pneumonia.
 Exanthem
subitum or Roseola infantum.
 Mononucleosis
with cervical lymphadenopathy.
Lab diagnosis:
 Peripheral
 Isolated
blood mononuclear cells – used
from the co-cultivation with cord blood
lymphs
 Viral
 PCR
Ag then detected by IF using monoclonal Ab.
– to amplify viral genome.
 ELISA
– detect virus Ag & Ab
 Virology
and clinical features similar to CMV.
 HHV
– 7 - Discovered is 1990.
 Roseola
infantum,
 Also
infects T lymph using same CD4 receptor.
 HSV – 8 – 1994 – Lymphotrophic rather than
neurotrophic.
 Kaposi
 These
 DNA
 2%
sarcoma associated in HIV infected.
people have Ab.
a aplification by PCR is method of choice
of general population have Ab.
 Herpes
B – simian virus – Occasionaly infect man
 Usually
fatal encephalitis.
 Occupational
risk in zoo keepers and cell culture
technicians.
 Latent
infection in monkeys.
 Herpes
B and HSV-1 cross react antigenically but
HSV-1 does not protect from encephalitis from
Herpes B.
 HSV-1
Ab confuse serologically – increase in Ab titer
difficult to interpret.
 Recovery
of virus is specific diagnosis.
 Acyclovir
beneficial.
 Prevention
– monkey bite, mask, clothing.
 Immunoglubulin
containing Ab to Herpes B to be
given after monkey bite
 Macrophages
 Isolation
are also infected so act as reservoir.
from saliva.