RNA viruses

Question 1

What makes up an influenza virus?

Answer 1

single stranded sense RNA
segmented RNA
envelope glycoproteins HA and NA critical for entry and egress of virus into host cell

Question 2

What HA and/or NA are a major human IVA?

Answer 2

H1, H2 and H3

Question 3

What new IVA virus has recently moved from birds to human?

Answer 3

H7N9 influenza virus A

Question 4

How did the H7N9 virus come about?

Answer 4

via re-assortment, where 2 or more infleunza viruses co-infect a single host and exchange genes

Question 5

How can influenza antigenic change?

Answer 5

structure of hemagglutinin (H) and neuraminidase (N) change

Question 6

What is a shift influenza change?

Answer 6

major change, new subtype
exchange of gene segment = no existing immunity
may result in pandemic

Question 7

What is a drift influenza change?

Answer 7

minor change, same subtype
point mutations in HA and NA genes
may result in epidemic

Question 8

What is a SARS-CoV-2 lineage?

Answer 8

phylogenetic cluster
associated with an epidemiological event

Question 9

What is the Middle East Respiratory Syndrome Coronavirus (MERS-CoV)?

Answer 9

camels may not show signs of infection however they may secrete MERS-CoV in nasal discharges, faeces, milk and urine

Question 10

What is the shape of Human immunodeficiency virus (HIV)?

Answer 10

icosahedral, enveloped ss(+) RNA

Question 11

What does HIV infect?

Answer 11

CD4+ cells by binding of viral gp120

Question 12

How does HIV replicate?

Answer 12

conversion of viral RNA to complementary DNA, which then integrates into host cell genome

Question 13

What are the two major forms of HIV?

Answer 13

HIV-1 and HIV-2

Question 14

What does HIV-1 cause?

Answer 14

almost all human infections

Question 15

What does HIV-2 cause?

Answer 15

less aggressive disease progression

Question 16

What is the most dominant HIV-1 group?

Answer 16

Group M

Question 17

How is HIV transmitted?

Answer 17

percutaneous and permucosal

Question 18

What happens in the early phase of HIV infection?

Answer 18

initial viruses are M-trophic (macrophage-trophic)
envelope glycoprotein gp120 is able to bind to CD4 and chemokine receptors called CCR5

Question 19

What happens in late phase HIV infection?

Answer 19

most cells are T-tropic (T-cell-tropic) having gp120 binding to CD4 and CXCR4 found on T4-lymphocytes
virulent and induce syncytia

Question 20

How do we diagnose AIDS?

Answer 20

CD4+ T cells <200 cells /μl
pneumocystis jiroveci pneumonia or one defining illnesses

Question 21

What is a long term non-progressers (LTNP)?

Answer 21

individuals who have attenuation of the HIV-1 genome, specifically the nef gene, which interferes with viral replication and can influence disease outcome

Question 22

What attribute in the CCR5 gene that causes a resistance to infection of HIV-1?

Answer 22

32bp deletion in the CCR5 gene

Question 23

What is the CCR5 gene?

Answer 23

is a 7-tm G protein-coupled chemokine receptor expressed on T cells, macrophages, dendritic cells and microglia