Herpesviruses

Question 1

What are herpesviruses?

Answer 1

Large enveloped dsDNA viruses with membrane glycoproteins

Envelope is sensitive to acid, detergents and drying

Has DNA polymerase which is the target of antivirals

Cell-mediated immunity required for control

Question 2

What kinds of infection can herpesviruses cause?

Answer 2

Lytic
Persistent (chronic)
Latent (reactivates under immunocompromised conditions)
Immortalizing (enters B cells and help cell to survive indefinitely, e.g. EBV)

Question 3

Pathogenesis of HSV?

Answer 3

Lytic infection of mucoepithelial cells, latent infection of sensory neurons

Avoids antibodies by cell-to-cell spread and syncytia
Cell mediated immunity is required to control and resolve infection

HSV1 above waist, HSV2 below waist but there is overlap
HSV 2 can cause neonatal HSV (can be fatal)

Question 4

Primary HSV infection symptoms?

Answer 4

Local pain, itching, dysuria, malaise, fever and headache
Systemic lesions
Tender lymph nodes

Gingivostomatitis, cold sores, keratitis, whitlow, genital herpes, encephalitis, neonatal herpes

Question 5

Recurrent HSV infection symptoms?

Answer 5

Reactivated due to stress or immune suppression

Lesions (e.g. herpes labialis, herpetic whitlow)
Virus shedding

Question 6

How to diagnose HSV infection?

Answer 6

Tzanck smear, immunofluorescence

Virus isolation

PCR

Question 7

How to treat HSV infection?

Answer 7

Acyclovir, targeting viral replication

Question 8

What does VSV cause?

Answer 8

Varicella - chickenpox
Zoster - shingles

Respiratory tract is portal of entry but has no respiratory tract symptoms

Primary viremia during incubation period
Secondary viremia causing fever and infection of skin (vesicular rash)

Latent infection in sensory ganglia

Question 9

How is VSV transmitted?

Answer 9

Respiratory droplets and direct contact

Question 10

Risk groups for VSV?

Answer 10

Immunocompromised patients and newborns
Elderly and immunocompromised at risk of recurrence

Question 11

How to diagnose VSV?

Answer 11

Clinical diagnosis

Atypical lesions? PCR, virus isolation, serology/IgG antibody test

Question 12

How to treat VSV?

Answer 12

Acyclovir

If neonate or immunocompromised patient is exposed, give VSV immunoglobulin

Vaccination via live attenuated virus

Question 13

Pathogenesis of EBV?

Answer 13

Can be lytic, latent or immortalizing

Found in saliva with asymptomatic shedding
Proliferates in oral epithelium and B cells
Immortalizes B cells, becoming latent
Reactivates when B cells are activated (controlled by T cells whose response contributes to symptoms of infectious mononucleosis)

Question 14

Symptoms of EBV?

Answer 14

Asymptomatic shedding
Pharyngitis, infectious mononucleosis
Burkitt’s lymphoma
Hodgkin lymphoma
Nasopharyngeal carcinoma
EBV-induced lymphoproliferative disease in immunocompromised patients (post-transplant, HIV)
Hairy oral leukoplakia

Question 15

Diagnosis of EBV?

Answer 15

Serology: antibody tests
PCR
Histology

Question 16

How to treat EBV?

Answer 16

No effective treatment or vaccine
Acyclovir not effective :(

Question 17

Pathogenesis of CMV?

Answer 17

Most adults carry the virus in latent form in saliva
Can be asymptomatic or cause infectious mononucleosis

Symptoms only show up in immunocompromised patients

Question 18

Symptoms of CMV infection?

Answer 18

Post-transplant infection (renal transplant rejection, bone marrow transplant pneumonia)
Retinitis, pneumonia, encephalitis, disseminated disease in HIV patients
Fetal infection in pregnancy

Question 19

How to treat CMV infection?

Answer 19

No vaccine, just screen organ transplant donors and supply leukocyte depleted blood

Ganciclovir, foscarnet, cidofovir reduce severity

Question 20

HHV6 and HHV7 symptoms?

Answer 20

Childhood rash (harmless but widespread)
Latent in T cells to cause post-transplant infection

Question 21

HHV8 symptoms?

Answer 21

Kaposi sarcoma, particularly in HIV patients

Question 22

How is HHV8 transmitted?

Answer 22

Sexual intercourse