Lecture 9 Flashcards
Emerging Viruses
What are some aspects of Coronavirus
Severe acute respiratory syndrome coronavirus 2 causes a respiratory infection called coronavirus
Enveloped virus with an RNA genome
Cause fever, dry cough, shortness of breath, pneumonia, and even death
What are some aspects of influenza virus
New strains of influenza virus arise fairly regularly as a result of mutations
H1N1 causes swine flu
What are some aspects of zika virus
Enveloped virus with a ssRNA genome
Primarily spread by mosquitoes; causes fever, rash, joint pain, conjunctivistis; can also cause Guillain-Barre syndrome
Zika during pregnancy can cause serious brain abnormalities including microephaly
Epidemiologist predict that millions of people will become infected with the Zika virus in the coming years
What are some aspects of AIDS and HIV
Human immunodeficiency virus (HIV) is the causative agent of acquired immune deficiency syndrome (AIDS)
HIV is primarily spread by sexual contact between infeated and uninfected individuals
Can also be spread:
- by transfusion of HIV-infected blood
- by sharing of needles among drug users
- from infected mother to unborn child
How does AIDS attack the immune system
The virus destroys a type of white blood cell called a helper T cell
Helper T cells play an essential role in the mammalian immune system
When T cells are destroyed by HIV, the immune system is seriously compromised
Patient becomes susceptible to opportunistic infections that would not occur in a healthy person
How does HIV replicate
Reverse transcriptase lacks proofreading function
Makes more errors
Tends to create mutant. strains of HIV
Undermines the body’s ability to combat HIV
What are the drug strategies for HIV
Inhibit proliferation, but do not eliminate the virus
Binds virus proteins (AZT)
Block proteases needed for capsid assembly (protease inhibitors)
What is a major challenge in AIDS research and how they attempt to solve it
Is to discover drugs that inhibit proteins without also binding to host cell proteins and inhibiting normal cell functions; second challenge is to develop drugs to which mutant strains will not become resistant
Use a cocktail (combo) to reduce drug resistance
What is some history of the origin of viruses
No fossil record available to provide evidence about viral evolution
Viral genomes follow the same rules of gene expression as the genomes of their host cells; depend entirely on host cells for proliferation
What is a hypothesis behind the origin of viruses
They evolved from macromolecules inside living cells - RNA. molecules or plasmids
Others argue for regressive evolution - viruses are degenerate cells that have retained the minimal genetic information for replication
Another theory is that viruses did not evolve from cells but evolved in parallel with cellular organisms
What are viroids
Composed solely of a single-stranded circular RNA molecule a few hundred nucleotides in length
Infect plant cells
Some replicate in host cell nucleus, others in chloroplast
RNA genome does not code for proteins; RNA of some viroidss have ribozyme activity
Disease mechanism not well understood
Affects many economically important plants
What are prions
Composed entirely of protein
Disease causing conformation
Normal conformation
Normal protein expressed at low levels on surface of neurons
Prion coverts normal proteins to abnormal form
Several types of neurodegenerative diseases of human and livestock
