Coronaviruses and Noroviruses
Coronaviruses and Noroviruses
3/29/13
Coronaviruses
Have crown or halo appearance
Crown is made of glycoprotein E2 which binds host cell.
Has large + RNA genome 25-30K bases
Enveloped virus
Very, very durable for enveloped virus.
Causes approximately 10% of cold-like illnesses
Usually limited to upper respiratory tract by temperature
Occasionally may cause mild viral gastroenteritis
Not deemed a serious human pathogen until 2003
SARS-Sudden Acute Respiratory Syndrome
Outbreak began in Guangdong province of China
Spread to Hong Kong and Canada
8100 recognized cases
770 deaths
Caused by SARS CoV
First case of current molecule genetics at work in current disease.
Virus was identified and genome sequenced within one month
Patients die of pulmonary edema caused by cytokine storm.
Glycoprotein E2 binds to ACE2 receptor in respiratory and GI tracts as well as sweat glands.
Unclear whether virus can spread through sweat
Second, minor outbreak in China in April 2004
Limited number of cases of SARS since
Noroviruses
Similar to picornaviruses
+ RNA of approximately 7500 bases with Vpg attached
Naked capsid that is very durable
Virus can persist for several days in the environment
Norwalk and Norwalk-like viruses are most common pathogens
Cause 30-50% of viral gastroenteritis
The virus can persist in low pH, high and low temp, chlorine, and detergents so it can be spread by a variety of transmission routes.
Contaminated food or water is most common.
People shed virus 10-14 days after symptoms stop
Food preparation workers may contaminate food after having an illness
Several major outbreaks on cruise ships have been linked to a single kitchen worker
Diseases are marked by cramping and diarrhea with nausea and vomiting. Many people have headaches 3-4 days after symptoms begin.
Hydration and rest are best treatments
Disease normally resolves after 2-5 days.
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