GI Viruses

Question 1

GI Virus Features

Answer 1

Virus Features – acid stable, enzyme resistant, usually fecal-oral transmission, environmentally stable (naked)

Question 2

Picornaviruses:

Answer 2

Picornaviruses: enteroviruses (mode of entry), much more stable than Rhinovirus, don’t generally cause GI disease

Question 3

Picornaviruses:

Answer 3

Properties – ss(+)RNA, icosahedral, naked, polyprotein expressed and cleaved
Genome – VPg cap to prevent degradation, preferential translation by host cell
Neutralizing antibody –cell-mediation not required, prevents interaction of virus with receptor
Entry – RNA is transported through a channel in the membrane

Question 4

Picornaviruses: Disease

Answer 4

– asymptomatic or mild flu-like symptoms, viremia → more severe disease

Question 5

Poliovirus

Answer 5

CNS tropism

Question 6

Poliovirus Asymptomatic

Answer 6

90% of cases

Question 7

Abortive poliomyelitis

Answer 7

Abortive poliomyelitis – 5%, minor illness, flu-like symptoms

Question 8

Non-paralytic poliomyelitis

Answer 8

– 1-2% aseptic meningitis, back pain and muscles aches

Question 9

Paralytic poliomyelitis

Answer 9

– rare, spread to ventral horn nerves and motor cortex/medulla → paralysis, withering leg

Question 10

Poliomyelitis Epidemiology

Answer 10

Epidemiology – current reported cases in Pakistan, Afghanistan, Nigeria

Question 11

Polio Vaccination: Inactivated

Answer 11

Vaccination –

Inactivated – denatured virus, stable, boosters required, no duodenal/nasal IgA, given at 2 and 4 months

Question 12

Polio Vaccination: Live virus

Answer 12

Live virus – longer immunity, not for immunosuppressed, increase in duodenal/nasal IgA, vaccine associated paralytic polio (VAPP)

Question 13

Coxsackie virus: Aseptic meningitis

Answer 13

Coxsackie virus:

Aseptic meningitis – fever, headache, stiff neck, photophobia, rash (younger)

Question 14

Coxsackie virus A

Answer 14

Herpangina – fever, painful ulcers of palate and tongue → vomiting, dysphagia
Hand-foot-mouth disease – vesicular lesions on palms, soles and oral mucosa

Question 15

Coxsackie Virus B

Answer 15

Pleurodynia – aka “Devil’s Grip”, fever and intense pleuritic chest and abdominal pain, 4 days
Myocardial/pericardial infections – cardiac tissue infiltrated with lymphocytes

Question 16

Rotavirus: Reoviridae

Answer 16

Reoviridae – respiratory, enteric, orphan → common cause of infant/child diarrhea in winter months

Question 17

Rotavirus:

Answer 17

Properties – segmented dsRNA, double shell capsid by budding through ER?
Replication – direct encapsidation, cytoplasmic replication
Classification – inner – VP6, outer –VP4,7 → antibodies against these antigens neutralize, group A is the major cause of human disease, 4 = G serotype, 7 = P serotype
Transmission – fecal-oral, cytolytic infection of gut epithelium → prevents water reabsorption, diarrhea, loss of electrolytes and carbohydrates
NSP4 – enterotoxin incorporated into ER membrane → glycosylated → active secretion

Question 18

Rotavirus Enterotoxin:

Answer 18

NSP4

Question 19

Rotavirus Tx

Answer 19

Tx – fluid replacement, RotaTeq vaccination to prevent severe form

Question 20

Caliciviruses:

Answer 20

Caliciviruses:
Properties – ss(+)RNA, naked, fecal-oral transmission
Norwalk virus – common on cruise ships, children
Sx - diarrhea, n/v, headache, fever, anorexia

Question 21

Astrovirus:

Answer 21

Astrovirus:
Properties - +RNA
Sx – endemic gastroenteritis, kids and infants, causes 10% of gastroenteritis