Lecture 13 - Human Viruses

Question 1

Orthomyxaviridae family of viruses is all ___ strand segemented RNA. ______ virus is a very common example.

Answer 1

• strand segmented

Influenza virus

Question 2

Transmission of the flu occurs via _____ secretions. Symptoms involve _____ (unlike a cold), chills, aches, and vomiting/diarrhea (esp. in children.)

Answer 2

Respiratory secretions

Fever

Question 3

Complications of Influenza include ______ (primary or secondary) and can exacerbate chronic health problems like asthma/CF, congestive heart failure, and COPD. Keep in mind the Influenza virus affects the entire respiratory tract, whereas the cold virus affects mostly just the upper respiratory tract.

Answer 3

Pneumonia

Question 4

There are two main types of Influenza: Type A and Type B. Only Type A can undergo antigenic _____, while both A and B can undergo antigenic _____.

Answer 4

Shift

Drift

Question 5

Seasonal Flu is a result of antigenic ____, while Pandemic Flu results from antigenic ____.

Answer 5

Drift

Shift

Question 6

The influenza virus has _____ segments of - strand RNA, each of which is dedicated to making a single protein product. Keep in mind once the influenza RNA enters the host cell, it travels to the _____.

Answer 6

8 strands

Nucleus

Question 7

Influenza is an _____ virus that uses its _____ protein to bind _____, which decorates plasma membrane proteins of host cells.

Answer 7

Enveloped

Hemagglutanin

Syalic acid

Question 8

______ is a protein that influenza virus uses to cleave syalic acid in order to prevent clumping of new viruses containing host cell plasma membrane which contains hemagglutanin and the syalic acid it binds to.

Answer 8

Neuraminidase

Question 9

Influenza virulence factors include _____ –> binds syalic acid on host cell membrane proteins, _____ –> cleaves syalic acid to allow for dissemination/prevent clumping, and ______ –> allows uncoating by decresing pH of virion.

Answer 9

Hemagglutanin

Neuraminidase

M2 ion channel

Question 10

The reason Type A influenza can undergo antigenic ____ (Type B can’t) is because there are multiple _____types that can mix segments (Random assortment) of their RNA genome within a host cell if 2 or more ____types infect the same cell.

Answer 10

Shift

Serotypes

Serotypes

Question 11

Antigenic ____ (which both type A and type B influenza can undergo) occurs as a result of mutations in Ab binding sites on _____ and/or _____. These mutations occur because _____ polymerase is highly error prone. There are 2 steps in which these errors/mutations can occur. The first is when the polymerase generates a ____strand from the ____strand viral RNA, and the second is when it does the opposite to get back to the ____ strand needed to form progeny.

Answer 11

Drift

Hemagglutanin

Neuraminidase

RNA polymerase

+ strand

• strand
• strand

Question 12

For a pandemic to occur:

1. Virus breaks ____ barrier
2. New Virus _____ detected in humans
3. Virus is highly _____
4. Virus efficiently transmitted between _____.

Answer 12

Species Barrier

Subtype

Pathogenic

Humans

Question 13

H5N1 (bird flu) is highly ____, but not highly ____, while H1N1 (swine flu) is just the opposite.

Answer 13

Pathogenic

Transmissible

Question 14

There are two vaccines available:

1. _____ (split) vaccine composed of 2 ___ subtypes and 1 or 2 ___ subtypes.
2. Live, ______ (cold-adapted) intranasal mist for healthy individuals ages 5-49. It’s composed of 2subtypes for both Type A and B.

Answer 14

Inactivated

2 A subtypes

1 or 2 B subtypes

Attenuated (cold-adapted = viable in lower temps around the nose but not in warmer temps further into the body, which prevents it from entering the lower portion of the respiratory tract.)

Question 15

Retroviridae are both ____ and ____ at some point in their life cycle. The ____ integrates into host ____ as part of the normal life cycle. _____ transcription is what converts ____ to ____. Keep in mind high rates of evolution are possible in retroviridae.

Answer 15

RNA and DNA

DNA

DNA

RNA to DNA

Question 16

Lentivirus (enveloped viruses like the others we’ve discussed) is the classification to which ____ (causative agent for AIDS) belongs.

Answer 16

HIV

Question 17

HIV binds human CD4 T-cells via the CD4 protein and _____ (or CXCR4) co-receptor. 1% of caucasians are homozygous for a deletion of this co-receptor, making them immune to HIV infection.

Answer 17

CCR5

Question 18

HIV viral _____, which process viral proteins made from viral DNA that was integrated into host DNA, are good targets for HIV therapy. Without a functional _____ the viral proteins will not be processed properly, and will be nonfuctional.

Answer 18

Proteases

Question 19

The HIV virus has only ____ genes, but each of these genes results in the production of a number of different proteins. Keep in mind the viral _____ is responsible for processing the gene products into the functional proteins.

Answer 19

3

Protease

Question 20

The viral load is what determines what happens in the short term while ____ counts measure the extent of damage.

Answer 20

CD4+ T-cell counts

Question 21

ART (anti-retroviral therapy) is a combination therapy that uses 3 HIV medicines from at least 2 different drug classes. The drug classes are as follows:

Non-____ and ______/nucleotide reverse transcriptase inhibitors.

Protease Inhibitors

Entry Inhibitors including _____ inhibitors (Block HIV’s entry into CD4+ T-cells) and _____ inhibitors (block interaction with CCR5)

Integrase inhibitors.

Answer 21

Non-nucleoside

Nucleoside/nucleotide

Fusion inhibitors (block entry)

Binding inhibitors

Question 22

Herpesviridae have large, linear _____ genomes and an outer envelope.

Answer 22

dsDNA

Question 23

alpha-herpesviruses include HSV1/2 and _____ zoster. They have a relatively rapid, cytocidal growth cycle but also establish _____ infection in sensory ganglia. Keep in mind the viral DNA does NOT integrate with host DNA

Answer 23

Varicella-Zoster Virus (VZV)

Latent

Question 24

HSV1 results primarily in ____ lesions, but also in genital lesions, while HSV2 is the opposite. 80% of the adult population is infected with HSV1. The infection is neurotropic/invasive and has a ____ life cycle, though it can become _____.

Answer 24

Oral

Lytic

Latent

Question 25

Herpesvirus disease mechanism: Virus penetrates into _____, where it replicates –> enters into cutaneous ____ and migrates to ganglion where it remains in a ____ state –> virus can subsequently be reactivated and travel through _____ neurons to the epidermis –> recurrent infection results.

Answer 25

Skin

Neurons

Latent

Sensory

Question 26

Herpesvirus life cycle occurs in waves, an immediate early, delayed early, and late mRNA wave. DNA synthesis and _____ assembly occur in the nucleus

Answer 26

Capsid

Question 27

Although there is no cure for Herpesvirus, symptoms can be relieved with anti-virals such as ______.

Answer 27

Acyclovir

Question 28

Acyclovir is a _____ analog that is used to treat alpha herpesvirus. It lacks an ____ group, which is the binding site for subsequent nucleosides. The reason Acyclovir only affects herpes infected cells is because only the herpesvirus has the ____kinase necessary to add the first phosphate group onto Acyclovir (_____ analog.) From there, the other two phosphates can be added by cellular kinases or viral kinases, and can thus be incorporated into the viral genome, blocking replication. This isn’t an issue for the infected nerve cells because they’re not actively _____.

Answer 28

Guanosine

OH

Thymidine kinase

Guanosine

Dividing