M: Virology 3 - Week 11 Flashcards by Alexander Bowden

Name 2 DNA viruses that can cause conjunctivitis

Adenovirus
Molluscum contagiosum

(also HSV and VSV but they are less important to remember)

How well did you know this?

Not at all

Perfectly

Name 2 RNA viruses that can cause conjunctivitis

Enterovirus 70

Coxsackie virus 24

How well did you know this?

Not at all

Perfectly

What type of cconjunctival infection is the most common?

viral conjunctivitis

How well did you know this?

Not at all

Perfectly

Where does viral conjunctivitis typically occur? (i.e. source of the infection)

Upper respiratory tract

How well did you know this?

Not at all

Perfectly

Are lymphoid follicles common or rare in viral conjunctivitis?

common

How well did you know this?

Not at all

Perfectly

Where do adenoviruses start? Where can they spread to and replicate? (3)

Start in glandular tissue. Can spread to conjunctiva, pharynx, GIT

How well did you know this?

Not at all

Perfectly

In regards to Adenoviruses, describe:
A: Capsid symmetry
B: Are they enveloped or non-enveloped?
C: Where are their fibres located?

A: Icosahedral
B: non-enveloped. Therefore are hardy
C: at their apices

How well did you know this?

Not at all

Perfectly

What conditions can adenovirus cause? (4)

ocular conditions (e.g. conjunctivitis)
respiratory
genital
GIT disease

How well did you know this?

Not at all

Perfectly

What virus is considered the most common cause of viral conjunctivitis?

Adenoviruses

How well did you know this?

Not at all

Perfectly

How may adenovirus ocular infections present? (2) What adenoviruses are responsible for each presentation?

Pharyngeal conjunctival fever (PCF) - adeno 3, 4, 7
Epidemic keratoconjunctivis (EKC) - adeno 8, 19, 37, others

How well did you know this?

Not at all

Perfectly

Why are adenoviruses difficult to disinfect against?

Because they are non-enveloped

How well did you know this?

Not at all

Perfectly

Describe the following features of adenoviruses:
D: how contagious are they?
E: how robust are they?
F: how long is their incubation period?

D: Highly contagious
E: Highly robust; survives in environment
F: Incubation period = 4-18 days long

How well did you know this?

Not at all

Perfectly

Describe the following features of adenoviruses:
G: How long do they survive on fomites?
H: Where are particles shed from (2) and for how long? (1)

G: 8-35 days
H: particles are shed from nasopharynx and tears for 2 weeks

How well did you know this?

Not at all

Perfectly

List 3 (out of the 11) symptoms of epidemic keratoconjunctivitis (EKC)

frequent dull pain, photophobia, reduced VA [important]
preauricular or submandibular adenopathy [important?]
significant periorbital lid edema
Marked conjunctival hyperemia, chemosis
Petechial haemorrhages common
Superficial punctate keratitis
Subepithelial infiltrates 1-2 weeks after onset

How well did you know this?

Not at all

Perfectly

Why can epidemic keratoconjunctivitis (EKC) present with submandibular adenopathy?

because adenoviruses are also replicating in glandular tissue such as submandibular glands

How well did you know this?

Not at all

Perfectly

How long after the onset of epidemic keratoconjunctivitis (EKC) do subepithelial infiltrates occur?

1-2 weeks after onset

How well did you know this?

Not at all

Perfectly

How long may subepithelial infilrates last in people with epidemic keratoconjunctivitis (EKC)?

weeks or months

How well did you know this?

Not at all

Perfectly

What age group is pharyngeal cconjunctival fever (PCF) predominantly seen in?

children

How well did you know this?

Not at all

Perfectly

What are midwinter epidemics of PCF due to? (1)

respiratory infections

How well did you know this?

Not at all

Perfectly

What are summer episodes of PCF associated with?

swimming pools

How well did you know this?

Not at all

Perfectly

Describe the following features of PCF:
A: unilateral or bilateral?
B: list 6 other symptoms

A: can be either unilateral or bilateral
B: 
tearing
fever
preauricular adenopathy
pharyngitis
occasional superficial punctate keratitis
subepithelial infiltrates

How well did you know this?

Not at all

Perfectly

In terms of preauricular adenopathy, how are EKC and PCF differentiated?

EKC: is tender
PCF: is not tender

How well did you know this?

Not at all

Perfectly

Describe the pathogensesis (in terms of replication) of adenoviruses in 4 steps

Bind well to CAR on mucosal epithelium
Enter cell via RME through clatherin coated pits
Acidification in the endosome modifies the capsid proteins
This allows release into cytoplasm and transport via microtubules to the nucleus for replication

How well did you know this?

Not at all

Perfectly

What does CAR stand for?

cell adenovirus receptor

How well did you know this?

Not at all

Perfectly

What contributes to the pathogenesis of adenovirus after replication? (3)

Release of new virions result in cell lysis (i.e. a cytotoxic virus) Some gene products suppress killing by cytotoxic T cells, so infection persists, stimulating large infiltrates of T and B cells Even after infection is cleared, persistant infiltrates may lead to loss in VA for weeks to months

How can we manage adenovirus infections? (4)

``` Supportive treatment (compresses, other pain relief, etc.) Instruct re-scrupulous handwashing to prevent spread Anti-inflammatory agents to reduce infiltrates (e.g. NSAIDs) Topical steroids (controversial, but consider for severe EKC) ```

Are there any specific anti-virals for adenovirus infections?

In regards to Enteroviruses, describe the following: A: What family of viruses do they belong to? B: What is their capsid symmetry? C: How big are they? D: Are they enveloped or non-enveloped?

A: picornaviridae B: Icosahedral C: Small D: Non-enveloped

Name the 2 subtypes of enteroviruses that are ocular pathogens

Enterovirus 70 | Coxsackie virus 24

In what age groups do we see enterovirus infections? (2)

children and young adults

In regards to Enteroviruses, describe the following: E: How contagious are they? F: How long is their incubation period? G: How are they transmitted? (2)

E: Highly contagious F: Rapid (24 hours) G: Fingers and Fomites (i.e. optometrists)

What proportion of enterovirus infections involve subconjunctival hemorrhages?

80%

Describe the course and recovery of enteroviruses (2)

rapid course with uneventful recovery

Can enterovirus infections present with a severe presentation?

yes

What symptoms do enterovirus infections present with? (3)

Sensation of burning or foreign body Eyelid swelling Photophobia

How can you manage enterovirus infections? (3)

``` Supportive treatment (compresses, other pain relief, etc.) Instruct re-scrupulous hand washing to prevent spread Topical NSAIDs ```

What family of virus does molluscum contagiosum belong to?

poxviridae

How does molluscum contagiosum affect the eye? (2)

chronic follicular conjunctivitis in association with an irritative eyelid lesion (nodules)

How is Molluscum contagiosum transmitted (in the eye)?

by direct contact with nodules

What is the incubation period of molluscum contagiosum in the eye?

14 to 50 days

What viruses can cause keratoconjunctivitis or keratitis? (3)

Adenovirus HSV (herpes simplex) VZV (varicella zoster)

``` In regards to Herpesviruses, describe the following: A: Capsid symmetry B: Enveloped or Unenveloped? C: How many types? D: How long can they be latent? ```

A: Icosahedral B: Enveloped C: 8 types D: all types can establish life-long latency

What are the 2 serotypes of HSV?

HSV-1 and HSV-2

How do you distinguish between HSV-1 and 2? (2)

``` Serological tests (detect antigens) OR PCR (detects genes) ```

What symptoms can both types of HSV cause? (2)

``` localised infections (e.g. cold sores, blepharoconjunctivitis, conjunctivitis, keratoconjunctivitis, keratitis, uveitis, genital herpes) AND disseminated infections (encephalitis, mengoencephalitis, etc.) ```

What symptoms are predominantly caused by HSV-1? (compared to HSV-2) (6)

``` cold sores blepharoconjunctivitis conjunctivitis keratoconjunctivitis keratitis uveitis ```

What symptoms are predominantly caused by HSV-2? (compared to HSV-1) (1)

genital herpes

In terms of the entry of HSV, describe the following: A: How is HSV acquired? B: What are the target cells (3) C: Name a particularly susceptible site

A: by direct contact of infected saliva (HSV-1) or other secretion B: Epithelial cells, Fibroblasts, Macrophages C: Mucous membranes

How does the entry of HSV work? (in terms of binding) (2)

Glycoproteins on envelope bind cell surface receptors | Binding triggers fusion of the envelope with the cell membrane and allows release of the nucleocapsid into the cytoplasm

In regards to replication of HSV in epithelial cells: A: How much virus is produced? B: Is the virus efficiently released? Where? C: How infectious is it? D: Is it symptomatic or asymptomatic

A: Large amounts of infectious virus B: NOT efficiently released into intercellular space C: Highly D: May be asymptomatic

In regards to HSV replication in epithelial cells: what leads to the infection of nerve cells in the trigeminal ganglion? (3)

infection of any of the ophthalmic, maxillary and mandibular branches of cranial nerve V by infected epithelial cells

What causes the latency of the HSV?

When HSV is maintained as an episome in ganglia (no replication)

How may recurrent HIV infections occur (at the original site)?

via reactivation from ganglia (in response to various stimuli such as stress

What does HSV infection of epithelial cells result in? (5)

``` rapid virus multiplication apoptosis spread vesicle formation infection of sensory neurons ```

Describe the process of establishment of latency in HIV (2 steps)

1. HSV infection of epithelial cells | 2. Axonal transport to dorsal root ganglion

What does axonal transport to the dorsal root ganglion achieve?

results in latent infection, the virus genome being maintained as an episome

What is an episome?

a genetic element inside some bacterial cells, especially the DNA of some bacteriophages, that can replicate independently of the host and also in association with a chromosome with which it becomes integrated.

Which ganglia do HSV1 and HSV2 typically go to when establishing latency? (2)

HSV-1: trigeminal ganglion | HSV-2: sacral ganglion

Describe the process of reactivation of HSV (3)

1. Certain stimuli and immunosuppresion induces reactivation of HSV from the episomal state 2. Virus is transported down the sensory nerve 3. Reinfection at the mucocutaneous site: results in a fresh outbreak of vesicles or asymptomatic shedding

Name stimuli that might induce reactivation of HSV (5)

``` fever sunlight UV light stress menstruation ```

During the reactivation process of HSV, how is the virus transported?

is transported down the sensory nerve

What does reinfection of HSV at the mucocutaneous site result in?

a fresh outbreak of vesicles or asymptomatic shedding

What associated conditions can primary infection of HSV-1 cause? (3)

stomatitis blepharitis conjunctivitis (typically unilateral)

Is recurrent eye disease after initial HIV infection common?

Yes. Rates of recurrence after initial infection are currently 10% at 1 year and 60% at 2 years

What is the most common cause of corneal blindness in the developed world?

HSV keratoconjunctivitis, keratitis

How common are posterior segment diseases resulting from HSV infection?

Rare

How can you manage HSV infection? (4)

Antiviral therapy: to prevent/reduce lesions Prophylactic oral acyclovir, valacyclovir, or famciclovir Physical barriers to reduce spread No effective vaccines yet

How can treatment with propylactic oral acyclovir, valacyclovir, or famciclovir affect HSV infection? (2)

significantly reduces the risk for recurrent HSV eye disease and adverse ocular events from HSV

What does primary infection by VZV cause?

Chickenpox

In regards to the pathogenesis of VZV: | A: What happens on day 0? (2)

Day 0: Infection of the conjunctiva and/or URT mucosa Viral replication in regional lymph nodes

In regards to the pathogenesis of VZV: | B: What happens on day 4-6? (3)

Days 4-6: Primary viraemia in blood circulation Further viral replication in liver and spleen Secondary viraemia

In regards to the pathogenesis of VZV: | C: What happens on day 10? (1)

Day 10: | Infection of skin and vesicular rash

What can recurrent infection of VZV cause? (1)

painful blisters of shingles that follow a dermatome

How can you manage VZV infection?

Minimise corneal damage and scarring Antiviral therapy (oral acyclovir, valacyclovir, famciclovir) Prevent spread by good hygeine VZV vaccine

Name 2 viruses that can cause congenital retinitis/chorioretinitis during/post delivery of the child

HSV and VSV

Name 2 viruses that can cause congenital retinitis/chorioretinitis after transplancental transmission

Cytomegalovirus | Rubella Virus

``` In regards to Rubella virus: A: What condition does it cause? B: What virus family does it belong to? C: Is it enveloped or unenveloped? D: How long is the incubation period? ```

A: German Measles B: Togaviridae C: Enveloped D: 18 day incubation period

In regards to Rubella virus: E: is it a DNA or RNA virus? F: How does it affect the skin?

E: RNA virus F: pink erythematous rash on the face and limbs

In what trimester of pregnancy does congenital rubella syndrome typically occur?

first trimester

How does rubella affect foetal development? (2)

slows down rate of cell division | babies are small and development of key organs in first trimester is impaired

Name 3 conditions that congenital rubella syndrome might cause

Retinitis Chorioretinitis Cataracts

How can you prevent infection with rubella?

Rubella vaccine

In regards to cytomegalovirus: A: What virus family is it in? B: Is it typically symptomatic or asymptomatic? C: How is it spread? (3)

A: Herpesviridae B: Typically causes asymptomatic infection (occasionally glandular fever) C: Spread by - close personal contact, blood, transplanted tissues

In what population does symptomatic infection of cytomegalovirus occur?

in immunosuppressed people (e.g. HIV, transplant patients)

Can cytomegalovirus cause congenital infection?

Yes. It is an important cause of congenital infection

Does cytomegalovirus target one or multiple organ systems?

Targets multiple organ systems, including the eye

What does reactivation of cytomegalovirus (CMV) cause?

CMV retinitis

How can you manage CMV retinitis? (3)

Ganciclovir I.V Intravitreal/oral valganciclovir HAART for HIV patients

Name 6 viruses that cause viral eye infections?

``` Adenovirus Enteroviruses HSV VZV Cytomegalovirus Rubella Virus ```