Ocular virology- ocular microbiology

1. DR. CHRISTINA SAMUEL
PG- M.S OPHTHALMOLOGY
MMCH & RI

2. GENERAL PROPERTIES OF VIRUS
Virus is the smallest known micro organism
[10nm-300nm]
It consists of a nucleic acid core(RNA/DNA)
surrounded by a protein coat.
They are metabolically inert and hence requires
living cells to survive and replicate.
The protein coat which is antigenic in nature is
called a ‘Capsid’ and together with the nucleic
acid is termed as ‘Virion’. The capsid is made up
of protein subunits called as ‘Capsomeres’

3. VIRUS
 ADENO VIRUS
 HERPES SIMPLEX
 HERPES ZOSTER
 CYTOMEGALOVIRUS
 PAPOVA VIRUS
 POX VIRUS- VARIOLA, VACCINIA, MOLLUSCUM
 PICORNA VIRUS
 PARAMYXO VIRUS
 RUBEOLA
 RUBELLA
 HIV

4. ADENOVIRUS- ADENOVIRAL CONJUNCTIVITIS
Family- Adenoviridae
Double stranded DNA virus without an envelope
70-90nm in diameter, icosahedral symmetry, 252 capsomeres.
Has an affinity for mucous surfaces and hence infect the
conjunctiva, pharynx and small intestine.
Humoral immunity plays a major role in combating adenovirus
infections and aslo a long lasting immunity is conferred against
reinfection.
Mode of transmission- hand to eye transfer, unsterilized instruments,
fomites, water borne(swimming pool)

5. ADENOVIRUS

6. Syndrome Adenovirus type
- Pharyngo conjunctival 3,4,7,14,21
fever, ARD
- Follicular conjunctivitis 1,2,3,5,6,7
- Epidemic
keratoconjunctivitis 8,19,37
(Shipyard eye)

7. SIGNS:
Conjunctiva- Eyelid edema, pre auricular lymphadenopathy,
conjunctival congestion, follicles, chemosis, rarely membranes
or pseudo membranes leaving a mild scar after resolution.
Cornea- Non staining epithelial microcysts, punctate epithelial
keratitis, focal subepithelial/anterior stromal infiltrates.
Mild anterior uveitis in some cases.
DD:-
Acute haemorrhagic conjunctivitis- enterovirus/coxsackievirus
Follicular conjunctivitis- HSV, varicella, mumps, measles,HIV

8. LAB DIAGNOSIS
- Giemsa stain- mononuclear cells
- Electron microscopy
- Virus isolation from conjunctival swab
- Cell line- primary human embryonic kidney cells, human epithelial
cells and MRC-5 cells( observe cytopathic effect) = ‘plaques’
- Complement fixation test
- ELISA & Enzyme Immunoassays
- PCR

9. ADENOVIRAL CONJUNCTIVITIS

10. FOLLICULAR CONJUNCTIVITIS

11. TREATMENT
Topical antibiotics
Lubricants
Topical steroids
Discontinue contact lens
Warm compressions
Hygiene- hand wash

12. HERPES VIRUS
Family- Alpha herpes virus
Double stranded DNA virus with a capsid and envelope.
150-200nm in diameter, 162 capsomeres
2 subtypes- HSV 1 & HSV 2
It multiplies in the nuclei of infected cells and produces
intracellular inclusion bodies “Lipschutz inclusion bodies”
Virus proliferates in the cells of the stroma and keratocytes and
sets up an inflammatory reaction.
It remains latent in the trigeminal ganglion- recurrent infection.
Primary infection- face, eye, mouth( 6mth-5yrs/newborns through
mother)
Latent infection-reactivation. May not involve the eye

14. CLINICAL FEATURES
Epithelial dendritic/geographic keratitis causing ulcer which stains
well with fluorescein dye.
Ends of the ulcer has terminal buds staining with rose bengal
Decreased corneal sensation. Scarring and vascularization in
prolonged cases. Disciform keratitis, necrotizing stromal
keratitis, neurotrophic ulceration
Keratoconjunctivitis and anterior uveitis
Preauricular lymphadenopathy, vesicular eruptions on the skin.
Fever and malaise
DD:-
Herpes zoster keratitis
Acanthaemoeba keratitis

15. CORNEAL ULCER

16. LAB DIAGNOSIS
Direct demonstration by electron microscopy/immunofluorescence.
Corneal scrappings- Giemsa/papanicola stain and intra nuclear
eosinophilic inclusion bodies can be demonstrated.
Cytology of infected tissue for multinuclear giant cells,
polymorphonuclear cells and monocytes.
Conjunctival fluid for virus culture- human embryo lung cells,BHK-
21,MRC-5 cells.
CPE occurs within 24-48hrs which is characterised by rounding of
cells and plaque formation.
ELISA

17. HERPES ZOSTER
Same group as HSV, but antigenically distinct.
It travels in a retrograde manner to the dorsal route and
cranial nerve sensory ganglia, where it remains dormant
for decades and gets reactivated when VZV-specific cell
mediated immunity fades.
HZO describes Shingles involving the dermatome supplied
by trigeminal nerve.

18. FEATURES:
Direct viral invasion- conjunctivitis, epithelial keratitis
Secondary inflammation with episcleritis, scleritis, keratitis,
uveitis, optic neuritis, cranial nerve palsy and cicatrizing
complications of eyelids.
Inflammation and destruction of the peripheral nerves or
central ganglia maybe responsible for post herpetic
neuralgia.
Reactivation causes necrosis and inflammation in the sensory
ganglia, corneal anaesthesia causing neurotrophic keratitis.
Skin vesicles occur which doesn’t cross the midline.

19. SHINGLES AROUND THE EYE

20. TREATMENT
Oral/ointment/topical Acyclovir.
Acyclovir Cream for skin lesions too.
Ganciclovir 0.15% gel
Oral valaciclovir/ famciclovir
Interferon monotherapy
Prostaglandins for IOP control
Topical/ oral steroids

21. CYTOMEGALOVIRUS
Family – Beta Herpes viridae
Double stranded DNA virus with icosahedral capsid and envelope.
Indistinguishable from HSV/VZV by electron microscopy.
Transmission is through placenta, intimate contact, blood
transfusion.
CMV has a profound immunosuppressive effect on the host and
has a tendency to persist in a latent state in the cellular
components of the blood.
Mononuclear phagocytes and natural killer cells play a role in
combating CMV infection.

22. FEATURES:
Keratitis
Cataract
Glaucoma
Microphthalmia
Retinal detachment
Optic atrophy
Chorioretinitis- multiple foci with a peripheral location
Retinal haemorrhages
DD:-
Toxoplasmosis

23. CMV- RETINITIS

24. LAB DIAGNOSIS:
Cytology – “OWL’S EYE” scanty cytoplasm and large nucleus with
acidophilic inclusion bodies.
Culture – human fibroblast cell lines. CPE shows rounding up of cells
in 2-3 weeks.
Serology – complement fixation test, ELISA and radio immuno
assays
PCR
TREATMENT:-
I.V Ganciclovir, Foscarnet, Cidofovir
Intravitreal vitrasert( ganciclovir slow release device)

25. CMV-VZV-HSV-TOXO

26. PICORNA VIRUS
RNA virus. A large family
27nm in diameter.
Icosahedral symmetry
Further sub divided
Enterovirus
poliovirus Rhinovirus
coxsachie
echovirus
enterovirus types 68-72

28. OCULAR LESIONS
ACUTE HAEMORRHAGIC CONJUNCTIVITIS-Coxsackie
A24, Enterovirus type 70
Transmission – fomites, faecal oral route, Direct inoculation into
the conjunctiva (contaminated fingers).
Incubation period – 2 days
It multiplies in the conjunctival epithelium and causes
haemorrhagic conjunctivitis.

29. LAB DIAGNOSIS
Virus Isolation: conjunctival swab inoculated into cell lines
like primary monkey kidney cell lines, Vero, HeLa. This
virus produces typical cytopathic effect.
Coxsackie: Isolated by suckling mice inoculation
Serology: Neutralization tests
TREATMENT:
Topical antibiotics

30. POX VIRUS
VARIOLA –
Commonly known as small pox virus. Brick shaped. 230-400nm.
Has an envelope.
Genome is a double stranded DNA and contains DNA dependent
RNA polymerase.
Causes Catarrhal purulent conjunctivitis, lid abscess, corneal pustule
and albinotic spots on the iris.
Lab diagnosis:-
Growth on Chorioallantoic membrane of yolk sac produces pocks.
Cytoplasmic eosinophilic Guarinieri bodies- light microscopy
Complement fixation test
Gutstein’s methyl violet stain

31. POX VIRUS

32. GUARINIERI INCLUSION BODIES

33. VACCINA VIRUS
Used as a small pox vaccine( induces immunity)
Transmission either by contamination or auto innoculation.
Signs :-
Lids – swelling, pustules, Ulcerative blepharitis
Purulent conjunctivitis
Marginal/disciform keratitis. Corneal pustule.
Pseudo retinitis pigmentosa
LAB:-
Growth on cell lines- HeLa, MRC-5
TREATMENT:-
Vidarabine and Iodoxuridine.
Topical and i.m use of vaccina immunoglobulin

35. PARAMYXO VIRUS
RNA virus, spherical in shape, pleomorphic, 150-300nm.
Enveloped virus having a hemagglutin(HN) and fusion(F)
glycoprotein spikes. HN is responsible for the host cell attachment
of the virus and F for fusion of viral envelope with host cell
plasma membrane.
Transmitted by droplet infection, humans being their only host.
Spreads to salivary glands.
Incubation period= 7-25 days
Ocular signs- Dacryoadenitis, optic neuritis, conjunctivitis, unilateral
stromal disciform keratitis.

36. LAB DIAGNOSIS
Immunofluorescence technique
Virus isolation by monkey kidney cell lines- rounding and giant cell
syncytium formation. Confirm by hemadsorption and
hemagglutination inhibition test using mumps virus specific
antiserum and immunofluorescence.
Complement fixation test
Haemagglutination inhibition test
Single radial hemolysis
ELISA
TREATMENT:- Oral supportive therapy

37. MEASLES- RUBEOLA
Enters the host via respiratory route and spreads to the lymph nodes.
Incubation period= 1-3 weeks
Both humoral and cell mediated immunity take part in combating
infection, has a life long immunity.
OCULAR MANIFESTATIONS-Conjunctivitis,
Koplik’s spots, SPK
LAB:-
Virus isolation from conjunctival biopsy
Direct immunofluorescence- microscopy
Culture- Cell lines- primary monkey kidney, human fibroblast cells
Serology- Hemagglutination inhibition test, complement fixation test,
neutralisation test.

38. RUBELLA- GERMAN MEASLES
RNA virus.
Family- Togaviridae.
Genus- Rubivirus
Spherical virus
70nm in diameter
Has a lipid envelope which has virus specific hemagglutinin spikes.
It Causes-
Post natal Rubella
Congenital Rubella syndrome{CRS}

39. CRS
Viremia occuring in pregnant women results in infection of
placenta and the differentiating cells of the foetus.
These children who are born secrete the virus in pharyngeal
secretions, urine and CSF fluid, which is detectable for 12-18
months.
Clinical triad of CRS=
Congenital heart disease+ Total/partial blindness(cataract,
glaucoma, chorioretinitis)+ Neurosensory deafness
Demonstration of IgM rubella antibody in infants is the Diagnostic
of CRS.

43. LAB DIAGNOSIS
Virus isolation from the specimen- Cell lines: Vero, RK-13
derived from rabbit, SRIC. In these cell lines it produces a
non specific cytopathic effect.
The virus can be demonstrated by- immunofluorescence with
specific antibody, interference method(using Coxsachie
antigen as challenge virus)
Serology- Hemagglutination Inhibition test: agglutinates
erythrocytes of 1day old chick, pigeon and sheep.
ELISA for IgG & IgM: Rise in IgG antibody titre should be
demonstrated in 2 serum samples and obtained at an interval
of 10-14 days. Else rubella specific IgM should be
demonstrated in a single specimen.

44. PREVENTION & CONTROL
MMR= Mumps, Measles, Rubella vaccine in a combined
form between 12-18 months of age.
Live attenuated MMR vaccine-
Routine vaccination of children < 12yrs
Immunisation of adolescents and children of child bearing
age.
Screening all pregnant women and immunising them

45. RETRO VIRUS
HIV belongs to the family Retrovirus and the genera Lentivirus.
Etiologic agent of Acquired Immuno Deficiency Syndrome.
It is a linear single stranded RNA virus. It is an enveloped Spherical
virus, 100-140nm in diameter, has a cylindrical bar shaped
nucleoid. Has the enzyme ‘Reverse Transcriptase’
HIV infects the T4 cells, monocytes, macrophages. As the disease
progresses T4 cells are destroyed and leads to reversal of T4:T8
ratio.
There is a decrease in production of Interleukins and Lymphokines,
abnormal activation of B-cells, Decreased natural killer cell activity
and impaired lymphocyte and macrophage functions.

47. PATHOGENESIS
Exposure to HIV
Pt is asymptomatic Symptomatic
Persistent glandular lymphadenopathy
AIDS
Immunosuppression
Opportunistic infection
Lymphoma
Kaposi’s sarcoma

48. ROUTES OF TRANSMISSION
Sexual route
Trans placental route
Contaminated blood and its products

49. HIV AND THE EYELIDS
Kaposi’s sarcoma
Multiple molluscum lesions
Severe herpes zoster ophthalmicus

52. HIV AND THE ORBIT
CELLULITIS:
From contiguous sinus infection
B-CELL LYMPHOMA

53. HIV AND THE CONJUNCTIVA
Kaposi Sarcoma
Squamous Cell Carcinoma

55. HIV AND THE CORNEA
KERATITIS - Due to
Microsporidium
Herpes Simplex
Herpes zoster

56. HIV AND THE EYE -
UVEA AND POSTERIOR SEGMENT
Anterior Uveitis
HIV Retinopathy
 Asymptomatic
 Multiple cotton wool spots

58. Retinitis - Due to
CMV-Vasculitis, Vitritis, Haemorrhages.
VZV-Progressive outer Retinal necrosis
Toxoplasmosis-Retinitis

60. Choroiditis:
 Pneumocystis
 Cryptococcus
B-cell Intraocular lymphoma

61. OCULAR MANIFESTATIONS IN AIDS
Ocular adnexal Kaposi sarcoma
Molluscum contagiosum follicular conjunctivitis
Herpes zoster ophthalmicus
Keratitis due to Microsporidia and HSV
Infectious conjunctival granulomas due to cysticercosis, TB and
fungus
CMV retinitis
Acute retinal necrosis syndrome due to HZV
Toxoplasma chorioretinitis
Syphilitic chorioretinitis
Ocular histoplasmosis
HIV retinopathy

62. DIAGNOSTIC TESTS FOR HIV
Non specific tests to detect immuno compromised state
Leucocyte count< 2000/mm3
Total CD4 count <200/mm3
Reversal of CD4: CD8 ratio
Raised IgG and IgA levels
Decreased platelet counts- thrombocytopenia
Diminished CMI by skin tests

63. Specific Tests:
Antigen detection P24 is the earliest viral marker.
IgM followed by IgG disappears within 4-8weeks.
Virus isolation - Tissue culture in embryonic kidney cells/ MRC-5.
PCR- DNA PCR / RNA PCR
Antibody detection
Screening with ELISA
Western Blot test- Confirmatory

64. TREATMENT
I.V Ganciclovir and Foscarnet are used in the treatment of CMV
retinitis.
Zidovudine and Didanosine are presently available, they block the
enzyme Reverse transcriptase.

65. Thank you