Microbio Lecture 9 - Viral Diversity

host range

spectrum of hosts a virus can infect

(narrow vs. wide)

viral specificity

specific kinds of cells a virus can infect

(affected by ability to attach, availability of cell materials, ability to be released)

classification of viruses

- type of nucleic acid (DNA or RNA)

- double or single stranded

- circular or linear DNA

- shape, size, envelope

- plus sense or minus sense

(+) sense RNA virus

can be directly translated into protein

(-) sense RNA virus

must carry viral RNA polymerase in the virion

bacteriophage

viruses of bacteria (no minus sense)

ssRNA (+) sense

- picornavirus

- Norwalk virus

- togaviruses

- flavivirus

- coronavirus

- retrovirus

picornavirus

- ssRNA (+) sense

- very, very small "pico"

- synthesis and maturation take place in cytoplasm

- viruses released via cell lysis

rhinovirus

- ex of picornavirus

- cannot survive in stomach

- common cold cause

polio

- ex of picornavirus

- resistant to many chemicals and low pH

hepatitis A virus

- ex of picornavirus

- inflammation of liver

Norwalk/norovirus

- ssRNA (+) sense

- small, naked

- gastroenteritis

togavirus

- ssRNA (+) sense

- small, enveloped ("toga")

- maturation involves budding

- rubella

- arthropod borne viruses (many)

flavivirus

- ssRNA (+) sense

- flavus = yellow

- enveloped

- transmitted by mosquitos and ticks

- Yellow fever

- West Nile, Dengue, Zika

Hepatitis C virus

- type of flavivirus

- blood contact

- no vaccine

coronavirus

- ssRNA (+) sense

- enveloped

- largest genome for RNA virus

- "crown"

- SARS, MERS, Covid19

retrovirus

- ssRNA (+) sense; 2 complete copies

- enveloped, spherical

- contains reverse transcriptase enzyme

- insert DNA into host chromosome (provirus)

- ex: HIV

ssRNA (-) sense

- rabies virus

- paramyxovirus (measles, mumps, RSV, parainfluenza)

- influenza

- Ebola, Marburg

- hantavirus

dsRNA

rotavirus

rhabdovirus

- ssRNA (-) sense

- medium sized; enveloped

- bullet shaped

- rabies virus (broad host range)

- Pasteur vaccine

paramyxoviruses

- ssRANA (-) sense

- large; enveloped

- mumps, measles, RSV, parainfluenza)

influenza A and B

- ssRNA (-) sense

- orthomyxoviruses

- medium, enveloped

- helical to spherical

- affinity for mucus

- genome in 8 segments

- surface antigens

Ebola and Marburg

- ssRNA (-) sense

- filoviruses

- enveloped, filamentous

- hemmoragic fever

hantavirus (bunyavirus)

- ssRNA (-) sense

- medium, enveloped, spherical

- genome in 3 segments

rotavirus

- dsRNA (-) sense

- small, naked, polyhedral

- gastrointestinal

dsDNA

- adenovirus

- herpesvirus

- poxvirus

- papillomavirus

- hepatitis B

ssDNA

parvovirus

adenovirus

- dsDNA (linear)

- medium, naked, icosahedral

- 12 antenna like fibers or spikes

- viral DNA goes into nucleus

- respiratory and gastrointestinal

herpesvirus

- dsDNA (linear)

- large, enveloped

- exhibit latency

poxvirus

- dsDNA (linear)

- very large, enveloped

- smallpox, cow pox, monkeypox

papovavirus

- dsDNA (circular)

- small, naked

- replicate in nucleus

- HPV

hepatitis B

- dsDNA (circular but partial ssDNA for replication)

- small, enveloped w/spikes, polyhedral

parvovirus

- ssDNA (linear)

- small, naked

- serious infection in dogs, Fifth disease in humans