LG 6.8 - Medical Virology

Question 1

Pandemic
Epidemic
Outbreak
Endemic
Seasonal
Sporadic
Eliminated
Eradicated

Answer 1

• Present in a widespread region, possibly worldwide
• Present at a higher level than usually found in a community or population
• Suddenly present in a distinct population
• Present at a fairly constant level
• Incidence peaks during a specific time of year
• Random, not associated with an outbreak
• No longer circulating in a given geographic region, control measures still necessary
• Permanently eliminated from circulation worldwide, controls measures no longer necessary

Question 2

(1) Emerging infectious diseases?
Re-emerging infectious diseases?
Deliberating emerging infectious diseases?

Answer 2

• Previously unknown or undetected infectious agents
• Known pathogens who incidence had decreased in the past but has reappeared
• Agents with potential to be used for bioterrism

Question 3

(1) Activities that increase exposure to infectious agents?

Answer 3

• Population movements
• Urbanization (old tires - mosquitos)
• Long-distance travel
• Natural disaster
• Global climate change
• Technologies (blod transfusions)

Question 4

(1) Activities that increase susceptibility to infectious agents?

Answer 4

• Microbial adaptation
• Poverty and social inequality
• War and famine
• Lack of public will
• Immunosuppresion
• opting out of vaccine.

Question 5

(6) What type of viruses replicate in the cytoplasm which in the nucleus?

Answer 5

• RNA is cytoplasm for the most part.

- DNA is nucleus for the most part.

Question 6

(6) For translation, what is the name of the site for the start of translation and what is the name of the end site on the DNA?

Answer 6

• Start = promotor region.

- End = polyadenylation site.

Question 7

(6) What do (-) sense RNA viruses have to bring with them, why?

Answer 7

• Bring their own RNA transcriptase.

- In order to replicate their (-) RNA into (+) RNA to be translated.

Question 8

(6) How do retroviruses translate their RNA?

Answer 8

• Reverse transcriptase into DNA back into RNA then translate.

Question 9

(7) How are mutations in viruses beneficial but also harmful for humans?

Answer 9

• Beneficial: can use these mutations to make viruses that are non-virulent in vaccines that will stimulate immune system but trigger no immune response. DI.
• Harmful: can use these mutations to evade our immune system (influenza). Phenotype mixing.

Question 10

(7) What is the difference between antigenic drift and shift?

Answer 10

• Antigenic drift: random mutations and virus genotypes drift from the origin.
• Antigenic shift: genetic shuffling between viruses to create new genotypes.

Question 11

How do naked (capsid-only) viruses enter host cell?

Answer 11

endocytosis (viroplexis)

Question 12

How do enveloped viruses enter the host cell?

Answer 12

endocytosis (virplexis) and direct fusion (only enveloped viruses can do this)

Question 13

how do enveloped viruses exit the host cell?

Answer 13

budding

Question 14

how do naked viruses leave the host cell?

Answer 14

lysis

Question 15

What are some characteristics of viral translation?

Answer 15

The most always follow rules of eukaryotic translation: 1. Contain a 5’ cap & 3’ poly(A) tail

2. Splicing in the nucleus, then exported
3. Be monocistronic (one mRNA = one protein) with initiation at first AUG