Virology

1
Virology -- Chapter 6 Size of
viruses Filterable viruses tobacco mosaic
virus bacteriophages Wendell Stanley and TMV
1935 found only protein and nucleic
acid Electron microscopy
2
Properties of viruses 1) no metabolism -- no
energy conversion 2) obligate intracellular
pathogens -- use hosts enzymes 3) no membrane
transport -- only holds receptors 4) replicate
by self-assembly 5) genome of RNA or DNA --
single- or double-stranded Are viruses alive?
3
Virus Structure The protein capsid Common
capsid shapes rod (helical) icosahedron Capso
meres
Human rhinovirus
poliovirus
4
Virus structure, cont Complex
viruses Enveloped viruses HIV
structure Bacteriophages
5
Viral replication Lytic cycle -- virulent
viruses Stages of a lytic cycle
T4 Infection
6
Viral replication, cont Lysogenic cycle --
temperate viruses integration provirus ind
uction Latency Retroviruses (e.g., HIV) RNA
genome reverse transcriptase RNA -----gt
DNA Mutational rates
7
Viral replication, cont animal viruses
penetration membrane fusion
vs endocytosis uncoating Release budding
Modes of Cell entry
Influenza penetration
Virus release
8
Viruses and latency Herpes (Herpes simplex
virus) HSV-I oral fever blisters HSV-II
genital herpes Induction Chickepox
(varicella-zoster virus) Shingles Viruses and
cancer (Human papilloma viruses) genital
warts cervical cancer Epstein-Barr Mono
(-nucleosis) lymphoma/leukemia Oncogenes
HSV infection
9
Viroids and Prions molecular
pathogens Viriods potato tuber spindle
virus (it isnt) replication Prions TSE
transmissable spongiform
encephalopathy Scrapie Kuru BSE Mad cow
disease
10
HIV and AIDS T-cells CD4 chemokime
receptor Stages of infection Protease
HIV replication
11
AIDS Clinical stages of infection 1. Acute
symptomatic 2. Chronic asymptomatic 3. AIDS
12
AIDS-associated diseases
13
Control of viral infections (or lack
thereof) Antibiotics dont work Synthetic
drugs -- symptoms -- low replication Anti-HIV
therapy 1) reverse transcriptase
inhibitors -- AZT, ddl, ddc, etc --
nucleotide analogs 2) protease inhibitors 3)
combinational drug therapy What about an AIDS
vaccine??
14
HIV prevalence among young adults ages 15 - 49
(WHO 2008)
AIDS Epidemiology Prevalence (vs
Incidence) HIV Clades A, B, C,
etc Transmission Cost of AIDS
drugs Health care issues