Lecture 13 - Human Viruses Flashcards
Orthomyxaviridae family of viruses is all ___ strand segemented RNA. ______ virus is a very common example.
- strand segmented
Influenza virus
Transmission of the flu occurs via _____ secretions. Symptoms involve _____ (unlike a cold), chills, aches, and vomiting/diarrhea (esp. in children.)
Respiratory secretions
Fever
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.
Pneumonia
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 _____.
Shift
Drift
Seasonal Flu is a result of antigenic ____, while Pandemic Flu results from antigenic ____.
Drift
Shift
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 _____.
8 strands
Nucleus
Influenza is an _____ virus that uses its _____ protein to bind _____, which decorates plasma membrane proteins of host cells.
Enveloped
Hemagglutanin
Syalic acid
______ 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.
Neuraminidase
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.
Hemagglutanin
Neuraminidase
M2 ion channel
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.
Shift
Serotypes
Serotypes
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.
Drift
Hemagglutanin
Neuraminidase
RNA polymerase
+ strand
- strand
- strand
For a pandemic to occur:
- Virus breaks ____ barrier
- New Virus _____ detected in humans
- Virus is highly _____
- Virus efficiently transmitted between _____.
Species Barrier
Subtype
Pathogenic
Humans
H5N1 (bird flu) is highly ____, but not highly ____, while H1N1 (swine flu) is just the opposite.
Pathogenic
Transmissible
There are two vaccines available:
- _____ (split) vaccine composed of 2 ___ subtypes and 1 or 2 ___ subtypes.
- Live, ______ (cold-adapted) intranasal mist for healthy individuals ages 5-49. It’s composed of 2subtypes for both Type A and B.
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.)
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.
RNA and DNA
DNA
DNA
RNA to DNA
Lentivirus (enveloped viruses like the others we’ve discussed) is the classification to which ____ (causative agent for AIDS) belongs.
HIV
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.
CCR5
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.
Proteases
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.
3
Protease
The viral load is what determines what happens in the short term while ____ counts measure the extent of damage.
CD4+ T-cell counts
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.
Non-nucleoside
Nucleoside/nucleotide
Fusion inhibitors (block entry)
Binding inhibitors
Herpesviridae have large, linear _____ genomes and an outer envelope.
dsDNA
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
Varicella-Zoster Virus (VZV)
Latent
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 _____.
Oral
Lytic
Latent
