Question

1-Fill in the blank: Efficient human to human transmission (spread) is required for an

influenza virus to cause a(n) _________.

2-true or False: Mutations of the CCR5 gene can confer a resistance to infection with HIV?

3-What role does the full length RNA and fragmented RNA play during norovirus replication?

4-Describe the Kaplan criteria for a norovirus infection ?

Answer 1

1.

• Efficient human to human transmission (spread) is required for an influenza virus to cause an infection / flu / pandemic . ( Note - u can fill any one of the terms here)

2.

• True
• CCR5 is a chemokine receptor . The CCR56 receptor first binds to HIV and infection proceeds.
• A muttaion in CCR5 receptor makes HIV unable to bind to cell and cause infection .
• Hence mutation in CCR5 confer resistance to HIV infection.

3.

• Norovirus is an RNA virus .
• The RNA of the virus itself acts as an mRNA .
• The full length mRNA contains genes for translation ,translocation and other processes necessary for viruses .
• The RNA of the virus also acts as primers for norovirus replication.
• If the RNA is fragmented then the virus is unable to perform its function and some processes like protein synthesis gets hampered.

4.

• Klapan criteria states that if i=mean duration of illness is around 12 to 60 hours .
• Incubation period of 24 to 48 hours
• No bacterial infection
• More than 50% of people affected and vomiting .
• If these cases are present then it is norovirus infection .