Download Herpes and Other Viral Diseases of the Eye

Viral eye infections….
and antivirals to treat
them
Herpes simplex virus type 1
Human herpesvirus, infects 40-70%
-Primary infection  neuronal latency and persistence for life 
sproradic or induced reactivation  Recurrence disease
Recurrent stromal keratitis
-immune mediated- collagen disorganization and scarring
-blindness requires corneal transplant
- defined by the genetics of virus and host
- Many shed very frequently- no disease!
epithelial keratitis
Stromal keratitis
Primary
infection
Infection of
neurons
latency
reactivation
of HSV-1
axonal
transport
Regulating HSV Lytic/ latent switch
-Latency in sensory neurons ( autonomic also?)
-viral DNA is episomal and highly chromatin regulated
-Only main expression is HSV Latency Associated Transcript
-LAT abundantly made at latency -No protein miRNAs?
-innate and adaptive cellular Immunity play a role in latency
Treating HSV-1 ocular disease
Primary infection and Epithelial keratitis
Antivirals– ACV or Valtrex- to remove and kill virus
Keratitis and stromal disease
-disease is immune mediated
-goal is to reduce inflammation
-STEROIDS
-ALWAYS USE AN ANTIVIRAL COVER!!!
Varicella zoster virus (VZV)
Human herpesvirus, related and like HSV-1
Chickenpoxneuronal latency (decades)
zoster (Shingles), pain and PHN
Primary VZV infection  Chickenpox
• Inhaled by aerosol
• Infects immune T cells
– tonsils/Waldemyers ring
– Transfer to T cells in lymph nodes
• Reaches skin by T cell viremia
systemic spread
• T cell Infiltrate skin –virus seeded in
dermal skin layers-
Perry and Whyte 1998
• 10-21 days- regulated by innate
(IFNa/b) until adaptive immunity
develops
• VZV cleared by adaptive immunity
• Problematic in adults- PneumoniaLumpkin E A et al. 2010
Establishment of the VZV latent state
• VZV in skininfects sensory nerve axon endings retrograde axon transport
• Also VZV in T cells directly infiltrate ganglia neuronal latency
• VZV systemic spread - entire neuraxis over body autonomic and sensory ganglia
Vaccination
Live Attenuated varicella vaccine- OKA
• Now mandated in US - 5+ years of age
• Live attenuated by passage in cuture
• -1200 pfu cell sonicate given in arm x 2
– Virus Infects body, but impaired in skin growth
long term protection from disease (not VZV infection)
• 86-95% effective in children
• Induces Herd Immunity- reduce spread in those not protected
Shift the incidence of chicken pox to older ages (adults)?
If no varicella-will this reduce boosting of immunity
throughout life from subclinical exposure?
• Lead to earlier zoster?
Herpes zoster
-in 1/3 of adult lifetimes
-one sided
--1 in 20 get zoster on head
Termed HZO if VZV reactivates from 5th cranial nerve
Disease limited to a dermatome
What’s different from HSV-1 reactivation?
- frequency and age
- ganglionic (zosteriform) spread
- ganglionitis and damage
- one neuron involved (HSV)
versus many (VZV)
Zoster- Risk Factors
Triggers of zoster?
 Age –
– 84% of cases occur after 60
– more in women

Cellular immune status
–
–
–
–
AIDS
Radiation Therapy
Cancer (esp. lymphoma)
medical immunosupression therapies


BMT & Transplants (30-55% in a year!)
CD4 appear more important than CD8 in
preventing zoster
 Is there subclinical reactivation during life?
Harpaz R et al 2008
Examples of ocular zoster
VZV Can infect every ocular
tissue to cause:

Punctate epithelial keratitis (PEK)
Dendritic keratitis
– -w/o terminal bulbi

Stromal keratitis/inflammation
– -Harder to treat than HSV-1

Neurotrophic keratitis
– -Total loss of corneal sensation
– -iatrogenic ulceration

Rarer Findings


Uveitis, retinitis,
Acute retinal necrosis.
Neurotrophic Keratopathy
The “diabetic foot” of the eye
•
~ 8% of HZO patients develop total loss of corneal sensation
~ 3% of HZO patients develop neurotrophic ulceration
Iatrogenic
insults are the main reason that neurotrophic corneas
get into trouble.
VZV and Pain
• 1 million people a year in the US
• 90% will seek prescribed medication
for pain
• 30% will develop debilitating chronic
pain Post Herpetic Neuralgia (PHN)
• Very difficult to treat (uses
• Many PHN patients get no benefits
from any form of treatment
Why is there pain?
Ganglionitis
Ganglionic necrosis
Neuronal connective plasticity and reorganization
Demyelyination
Cell-Neuron Fusion-cytoplasmic mixing
Other ocular/ neurological complications of VZV
•
Most are rare and
mis-diagnosed
•
Persistent VZV in
CNS vasculature or
CNS/brain
leads to ….
•
•
•
•
•
•
Cognitive
deficits
Stroke
Headaches
Migraines?
seizures
Vaccination to prevent zoster
– Zostervax- same as varicella vaccine- 14X more virus
– VZV immune people get it.
– Recommended > 50 yrs, may eventually need two doses
– Is the only human herpesvirus vaccine so far
– Partial efficacy - not everyone is protected
– 51% drop in zoster incidence
– 68% fall in “burden of illness” (including PHN)
Adenovirus follicular conjunctivitis
vs others-differential diagnosis
Adenoviral
Infections
• non-enveloped virus,
• 34Kbp DS-DNA, many viral proteins
• At least 57+ identified Serotypes
• Three major ocular diseases
• Epidemic Keratoconjunctivitis (
8, 19 and 37+ several
new serotypes and interrecombinant strains)
• Pharyngoconjunctival fever (3,4, & 7)
Epidemic Kerato-conjunctivitis

transferred by hands, instruments, solutions.

Adenoviruses survive >35 days on dry surface

Epidemics arise from ophthalmologists offices.
Patients remain infectious for 14 days after onset
Usually One eye, then other (milder)
Lasts 7 days -2 weeks

Source of new isolates- Japan/Asia
- Japan-EKC is a reportable disease
- Hawaii west coast -mixing ground




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Clinical Symptoms
Foreign Body Sensation
Tearing
Photophobia
Sore Throat
Breathing Problems
Conjuntivitis
NO ANTIVIRAL – YET
– -Correct timely diagnosis an issue
After virus…...
-Subepithelial infiltrates
(immune mediated)
-last weeks to months
- treat with steroids
- requires slow withdrawal
Adenovirus EKC management
Ebola Virus
EBV in Ocular Fluid during convalescence Varkey, JB et al NEJM,
2014
Zika virus

Human RNA alphavirus
 transmitted by mosquitos
 Also transmitted in utero and by sexual contact

80% have no symptoms

Fever rash, arthritis and conjunctivitis are common
No known antiviral or vaccine – yet
 Of most concern is ocular development in
newborns with microcephaly

Ocular complications
in newborns
• Retinal bleeding (Hemorrhagic retinopathy)
• Abnormal blood vessel development (missing vessels)
• Torpedo maculopathy (topedo shaped lessions in macula
A model of Zika and eye disease?
Miner et al., 2016, Cell Reports 16, 3208–3218
September 20, 2016
Highlights
a. ZIKV infects several different
regions of the eye, including the
Retina.
ZIKV infected the iris, cornea,
retina, and optic nerve and caused
conjunctivitis, panuveitis, and
neuroretinitis in mice.
b ZIKV RNA can be detected in
tear fluid
c Eye and brain infection in adult
mice by ZIKV occurs
independently of the AXL
receptor
d ZIKV infection results in
apoptosis of neurons of the
visual processing pathway
CMV and retinitis
• 80% are seropositive
• Virus is endemicearly childhood
• Usually asymptomatic
• Retinitis Rare outside
of HIV/AIDS
-A major factor in “will to live”
Of AIDS patients
Signs
Photophobia
Eye Pain/redness
Floaters
Vision loss
Usually initiates monocular
Other Viruses causing
conjunctivitis or Eye Disease

CM and EBV herpesviruses affecting most people
– may cause conjuntivitis and ,rarely, corneal keratitis

Entero/coxsaccivirus- Hemorrhagic conjunctivitis
-begins as eye pain, then red, watery eyes with swelling,
-
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light sensitivity, and blurred vision.
HIV (and everything resulting from it)
Newcastle disease virus
Vaccinia Mollocsum contageosum (lid lesions)
Papilloma (lid lesions)
Measles (Conujuntivitis)
Important Ophthalmic antivirals
Triflorothymidine (viroptic)
HSV-1>> VZV
Acyclovir and valacyclovir
HSV-1 and VZV
Ganciclovir and valganciclovir
CMV retinitis, Adeno,
Foscarnet (phosphonoformate)
CMV (GCVr)> HSV,VZV
Cidofovir
CMV (GCVr)
HAART
HIV/AIDs
Trifluridine (viroptic)
Analog of deoxyuridine nucleoside
Incorporated into DNA
CF3 blocks base pairing in DNA
Has higher affinity for viral DNA pol
over cell pol
Used topically only- toxic systemically
Acyclovir, gancyclovir and
derivatives
Acyclovir (FDA licensed in 1981)
Use
Herpes simplex virus
Varicella Zoster virus
human cytomegalovirus
0.1-3 ug/ml
5-20
60-200 (not deemed “clinically effective”)
Safe in Long term Prophylaxis treatments
Prodrug mechanismonly active in virus infected cells
Virtually non toxic in uninfected cell
100 x more active in HSV—1 infected cell.
Once activated, has higher affinity (50x) for HSV DNA polymerase over
cellular DNA polymerase.
ACV
Mechanism of Action
–HSV VZV Thymidine (nucleoside) Kinase activates it
–ACV TP binds Viral DNA polymerase >>>>> cell pol
–Incorporated into DNA - acts as DNA chain terminator
ACV - Resistance

Readily arises in culture
– Defect /loss of viral TK
– Mutation of DNA polymerase- alters ACV affinity

rarely occurs in vivo- why?
–
–
–
–
–
Latency in neurons
TK needed for HSV reactivation
TK- viruses don’t reactivate
ACVR arise In AIDS patients with long treatments




Have Pol mutations: or
Low persistent viral replication: or
Have minimal TK levels
sufficient to enable reactivation from latency
– Not sufficient to activate/ phoshorylate ACV
Oral forms of Acyclovir
Liver
Acyclovir
ACV
Valacyclovir
“Valtrex”
alone is degraded by the stomach
Valine
Ester derivative has high oral- bioavailability
–e.g. 63-72% absorption vs 15% for ACV
Is
de-esterified by liver on first pass  ACV
Allows
reduced dosing and taking by mouth
GMP
O
Ph
O
N
N
N
Gancyclovir
N
N
O
To 5’
end
N
N
N
O
N
N
O
O
O to 3’ end
Gancyclovir and
Valgancyclovir drugs to combat
HCMV disease
Ganciclovir (Cytovene)

used for hCMV
also used for stubborn VZV and HSV

works much better than ACV for CMV disease
– retinitis and systemic disease in transplant patients
BUT
GCV Requires IV dosing but val-GCV (ester form) by mouth
– GCV is More toxic than ACV- Why?


GCV-PPP also inhibits host cell polymerasemuch less selective
– GCV Does not cross retinal/brain barriers well
Often use ocular implants for retinitis
GCV increases AZT toxicity- bad for HIV patients


GCV-a
Mechanism of action
GCV
DNA chain terminator
O
–CMV has no TK gene
–CMV uses a protein kinase (UL97) to
phosphorylate GCV (and ACV)
N
N
GCV Resistance
O
• Arises due to long treatment for CMV diseases
(upto 10% In Retinitis and organ transplants)
N
N
O
O
•Rare- mutations in UL97 protein kinase
•( UL97 is needed for hCMV to efficiently assemble)
•Mutations in DNA polymerase that alter affinity
• High GCV-resistant CMV have both genes altered
N
Foscarnet (phosphonoformate, PFA)
• Mechanism of action:
–
–
–
–
–
All polymerases need P-P as cofactor
PFA analog of pyrophosphate (P-P)
binds to DNA polymerase
PFA blocks P-P binding
resistance – altered DNA polymerase
P-P
O
OH
OH P
P OH
OH O
• Efficacy/toxicity
– active on nucleoside resistant viruses
• Acts at different site to GCV/ACV
– Toxic in bone, kidney, neuronal deposits
• Uses:
– CMV retinitis and GCVr CMV in transplants
– rare use on HSV and VZV ARN
– Rare use on systemic HSV and VZV
O
OH
OH
P
OH
PFA
CH
O
Nucleoside phosphonates
•Cidofovir
•Licensed for CMV retinitis
•Analogs of dNMPs – no initial P step needed
• CDV has long intracellular half life
•Has activity to many viral DNA polymerases
•Works against :
many adenoviruses,
poxviruses, -(used if smallpox resurrects?)
herpesviruses , polyomaviruses, HBV?
Could be the universal antiviral drug in not so toxic
Lipid Conjugate Technology
Exploits Natural Phospholipid Pathways
CMX001
Lysolecithin
Polar head
Non-polar tail
Cidofovir
Lipid conjugation
enhances absorption and distribution
CMX001
Cidofovir
 Broadly active against dsDNA

Orders of magnitude more potent
than CDV; broadly active

Initially being developed for
adenovirus, CMV and smallpox
 Requires intravenous infusion

Orally available
 Black box warning for renal

No evidence of nephrotoxicity or
myelotoxicity
viruses
 Approved for treatment of CMV
retinitis in patients with AIDS
impairment and neutropenia