Microbiology-Enteroviruses

Question 1

Name 5 enteroviruses

Answer 1

Coxsackievirus A/B, echovirus, enteroviruses and polioviruses.

Question 2

What is the structure and genome of picornaviruses?

Answer 2

Structure: non-enveloped, 2,3,5 isocahedral. Genome: +ssRNA.

Question 3

What type of picornaviruses are inactivated when you swallow them?

Answer 3

Rhinoviruses. They are only virulent in the oropharynx and nasopharynx. The low pH of the stomach inactivates them.

Question 4

How do you get infected with enteroviruses?

Answer 4

Ingestion -> travels to gut -> +ssRNA genome injected from capsid into enterocyte -> host ribosome replicates protein -> viral enzymes are snipped out and autofolds into capsid -> cell lyses and viruses travel to other cells. Ultimately the host will become viremic and the virus’s target tissue will manifest typical symptoms.

Question 5

What is the major reason that different picornaviruses infect different target organs?

Answer 5

The picornavirus has a “canyon” that binds specific adhesion molecules in different organs (for example rhinovirus’s canyon binds ICAM-1)

Question 6

Why are shellfish dangerous as far as enterovirus transmission goes?

Answer 6

The naked capsid is resistant to mild sewage treatment, salt water, detergent and temperature changes. When sewage is treated and sent into rivers and streams, enteroviruses from humans are concentrated in shellfish.

Question 7

Since picornaviruses are lytic, what changes will you start to see on host tissue?

Answer 7

CPE: viruses will lyse cells and cause cytopathic effect, or dying off of cells.

Question 8

Where are vaccines most effective during an infection of a picornovirus?

Answer 8

Viremia. The antibodies can block canyon binding of the virus to the target cell.

Question 9

What is the reservoir of poliovirus?

Answer 9

Humans.

Question 10

How many serotypes are there in poliovirus?

Answer 10

Types 1, 2 and 3

Question 11

Salk vs. Sabin polio vaccines, which is better?

Answer 11

SalK = killed. Sabin = live attenuated. You get more secretory IgA with the live attenuated virus and you get a more natural antibody response.

Question 12

Why do most countries use the oral polio vaccine (OPV)?

Answer 12

You only need one dose. In the US we use 4 doses of the killed vaccine because all cases of paralytic polio disease are traced back to the children receiving a live attenuated vaccine, the virus reverts and infects the caregivers.

Question 13

A previously healthy 25 year old medical student presents to your clinic with elevated bilirubin and serum transaminases. He has been ill for the last 12 days a slight temperature (99.5F). He also has felt nauseated with abdominal pain, and has vomited on several occasions. History of travel includes a trip to Louisiana 3 weeks prior and reports eating raw oysters. He denies the use of recreational drugs. Considering possible causes for his disease, what virus is most likely involved?

Answer 13

He has acute hepatitis, most commonly seen in Hep A infections.

Question 14

Viruses associated with rebelliform rashes

Answer 14

Coxsackie A/B and echoviruses

Question 15

Coxsackievirus that causes myositis.

Answer 15

Coxsackie A

Question 16

Coxsackievirus that infects the brain.

Answer 16

Coxsackie B

Question 17

Several middle school patients present with vesicular lesions around the mouth, feet and hands. What virus is most often associated with this outbreak?

Answer 17

Coxsackie A virus, note however, that many kids won’t present the same way. Some kids may present with meningitis, paralytic disease or even myocarditis. A characteristic of a coxsackie outbreak is that it is rapidly explosive because it is easily transmitted and very stable.

Question 18

A young child presents with the lesions in the back of his throat shown below. He had a low grade fever. It is summer time. What virus causes this?

Answer 18

Coxsackie A

Question 19

What diseases is echovirus commonly associated with?

Answer 19

Acute febrile illness in kids, aseptic meningitis, paralysis, myocarditis and rashes.

Question 20

Viruses that can cause this type of rash

Answer 20

Measles, strep and enteroviruses can all cause maculopapular rashes.

Question 21

When are peak outbreaks of echovirus and coxsackieviruses?

Answer 21

Summer, when kids are out playing together

Question 22

How do you diagnose enteroviruses?

Answer 22

Coxsackie B and echovirus are easily isolated in cell culture. Coxsackie A cannot be isolated in cell culture.

Question 23

In July of 2011 there was a sudden outbreak of low-grade fever, muscle pain, and rash among 65 middle-school children in Bethesda, Maryland. All of the patients complained of muscle ache, but only 50%developed a maculopapularrash. What is the MOST LIKELY cause of this episode?

Answer 23

Enterovirus. Only half the kids got the maculopapular rash, which development is dependent on T-cell immunity. If this were measles, all the kids would’ve gotten the rash.

Question 24

Virus that causes acute hemorrhagic conjunctivitis

Answer 24

Enterovirus 70

Question 25

Virus that causes epidemics of aseptic meningitis, encephalitis and paralytic hand-foot and mouth disease. Many children die from this.

Answer 25

Enterovirus 71