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Virology Review 4

Emerging Viruses

Definition of EMERGING New or recently identified viruses to humans
Defintion of REEMERGING viruses once thought to be under control but are reappearing
Examples of Emerging Viral Disease HIV?AIDS, Hantavirus pulmonary syndrome (HPS), West Nile encephalitis (WNV), Severe Acute respiratory syndrome (SARS), and Monkeypox
Arboviruses arthropod-borne viruses, all RNA viruses
Future HCV (Flaviviridae) Account for 40-50% of chronic liver diseases, unknown transmission route
Point-Mutation Rate of RNA viruses 1 per 10,000 nucleotides
Point-Mutation Rate of DNA viruses 1 per 100,000,000 nucleotides
Antigenic Drift mutations caused by replication error
Reassortment occurs when very similar segmented viral genomes coinfect the same cell. Example: Influenza A
Recombination - 2 viruses occurs when 2 viruses infect same cell & a new chimeric or hybrid genome is formed via intramoleculr exchange of viral genomes. occurs when viral RdRp complex switches, mid-replication, from one RNA molecule to another. Example: SARS-CoV & coronaviruses
Recombination - stealing host genes virus steal genes from host through recombination with the cellular chromosome. Example: Retroviruses
Antigenic Shift occurs by gene swapping, either between 2 viruses, or between virus & host cell
Norovirus Can not be cultured in lab, no animal modeals, hard to determine genetic changes in the virus that trigger outbreaks
Crossing species border: exotic pet trading Example: Monkeypox
Crossing species border: free-range farming
Crossing species border: live markets Example: SARS
Extension of farmland into unused land exposes farmers to zoonotic diseases (especially rodents carrying viruses)Example: 1958-1974, Argentine hemorrhagic fever (caused by Junin viruses carried by rodents)
Deforestation is the removal of trees in forests (e.g. Amazon) 2005 Brazil, vampire-bat related rabies1998-1999 Malaysia, Nipah virus infecting pigs, humans, dogs and cats
Importing Animals for Biomedical Research and Vaccine Production Example: 1967, Infected African green monkeys imported to Marburg, Germany and Belgrade, Yugoslavia for research and preparation of poliovirus vaccine; Monkeys infected with Marburg virus—cause of hemorrhagic fever in humans (high mortality rate)
Environmental Changes 1993: 4 Corners Area, U.S. Sin Nombre hantavirus outbreak (deer mouse was the carrier)Correlated with rainfall increase, more piñon nuts (food for deer mice)
VIRAL INFECTIONS THAT MAY BE/HAVE BEEN CONTROLLED Must have human or readily controllable reservoir; Must be able to induce an effective and lasting immune response; Effective vaccine (Ex. Smallpox, Next polio and measles?)
OTHER VIRUSES WILL NOT BE ELIMINATED Viruses that cause persistent infections; Viruses that counter the immune system (Ex. HIV); Viruses that have a nonhuman reservoir (arboviruses)
Human Bocavirus (HBoV) An Emerging Viral Pathogen? a new virus found in respiratory secretions of Swedish children with lower respiratory tract infections; HBoV cannot be cultivated in the laboratory.
Created by: lbr9349