44 Questions
What is the result of antigenic shift in influenza viruses?
Drastic reassortment leading to a pandemic
What type of influenza virus causes epidemics every 3-6 years?
Type B
What is the property of the Hepatitis virus that allows it to have high frequency recombination?
Deletion mutation
What is the name of the virus that causes hepatitis?
HAV
What is the shape of the Paramyxovirus virion?
Spherical
What is the shape of the Coronavirus virion?
Pear-shaped
What is the mode of infection for Paramyxovirus?
Respiratory droplets
What is the genome type of the Coronavirus?
Non-segmented, (+) sense, ssRNA
What is the disease caused by swelling of the airways and problems breathing?
Croup
What is the mode of transmission of MERS-CoV?
Respiratory droplet
What is the site of multiplication for Paramyxovirus?
Cytoplasm
What is the diagnosis method for Filovirus?
Cell culture and modern molecular techniques
What is the fatality rate of MERS-CoV?
34%
What is the result of antigenic drift in influenza viruses?
Mild reassortment leading to the formation of a new strain
What is the shape of the Picornavirus virion?
Icosahedral
What is the virion shape of the Filovirus?
Filamentous
What is the mode of transmission of Dengue fever?
Vector-borne
What is the family of viruses that includes Coxsackie virus?
Picornaviridae
What is the genome type of the Flavivirus?
Non-segmented, (+) sense, ssRNA
What is the host cell affected by the Coronavirus?
Upper respiratory tract
What is the method used to confirm repeatedly reactive samples?
Western blot assay
What is the shape of the HIV virion?
Rod-shaped or bullet-shaped
What is the basis of HIV disease staging?
CD4+ cell counts and opportunistic infections
What is the site of HIV multiplication?
Cytoplasm
What is the method used to determine viral load?
RT-PCR
What is the primary mode of transmission of the rabies virus?
Direct contact with infected animals
What is the natural host of the Simian immunodeficiency virus (SIV)?
Sooty mangabey
What is the distribution of HIV-1?
Cosmopolitan
What is the primary receptor for the HIV virus?
CD4
What is the shape of the HIV virion?
All of the above
What is the result of the destruction of T cells by the HIV virus?
Immune function deteriorates
What is the role of CXCR 4 and CCR5 in the HIV virus?
Co-receptors
What is the characteristic of the HIV genome?
Linear, non-segmented, (+) sense, ssRNA
What is the stage of the HIV infection where the patient remains asymptomatic for many years?
Clinical latency
What is the mode of transmission of the HIV virus?
Sexual and parenteral
What happens to the host's immune function during the clinical latency stage?
The host is able to replace infected T cells faster than they are destroyed
What is the primary tissue infected by the virus?
Muscle tissue
How does the virus migrate to the CNS?
Along the peripheral nerves
What is the outcome of AIDS-associated infections in humans?
Death
What is used to diagnose AIDS?
Serology techniques
What is the first stage of the disease?
Prodromal stage
What is a common symptom of the sensory excitement phase?
Hyperactivity
What is a complication of AIDS-associated infections?
All of the above
What type of virus is involved in AIDS?
Retrovirus
Study Notes
Hepatitis Viruses
- Virulence factor: high frequency recombination (Deletion mutation)
- Diagnosis: RT-PCR, Antigen-Detection Kits, Antibody Testing
Coronavirus
- Family: Coronaviridae
- Virion: enveloped, “pear-shaped” peplomers giving a crown-like appearance
- Largest RNA virus
- Genomic characteristics: non-segmented, (+) sense, ssRNA
- Multiplication: R (CYTOPLASM); AM (ER)
- Infects: upper respiratory tract
- MOT: respiratory droplet
- Contains S protein (spike) which causes cell fusion and facilitates viral entry to host cells
Filovirus
- Family: Filoviridae
- Virion: Filamentous, thread-like, enveloped with large peplomers, helical capsid sometimes irregularly shaped
- Genomic characteristics: non-segmented, (-) sense, ssRNA, striated core
- Multiplication: RA (CYTOPLASM); M (CM)
- Infects: macrophages, endothelial cells, hepatocytes
- MOT: respiratory droplets and body fluids
- Diseases: Ebola virus - short virus with 2-21 days incubation, Marburg virus - long virus with 4-16 days incubation
Influenza Viruses
- Type A, B, and C
- Diseases: primary influenza pneumonia, croup, otitis media
- Antigenic shift: drastic reassortment, every 10-40 years, leads to a pandemic
- Antigenic drift: mild reassortment, accumulated point mutations lead to formation of new strain
- Examples of Influenza Epidemics and Pandemics: Spanish flu (1918-1919), Russian flu, Asian flu (1957), Hong Kong flu (1968)
Flavivirus
- Family: Flaviviridae
- Virion: spherical, enveloped, icosahedral
- Genomic characteristics: non-segmented, (+) sense, ssRNA
- Multiplication: R (CYTOPLASM); AM (ER)
- Infects: macrophages (Dengue), CNS (Encephalitis), Hepatocytes (HCV & yellow fever)
- MOT: Aedes aegypti (Dengue), Arthropod bite (Encephalitis), parenteral (HCV), Aedes or Haemagogus spp.
Paramyxovirus
- Family: Paramoxyviridae
- Virion: spherical, helical capsid, enveloped, HA, NA spikes
- Genomic characteristics: non-segmented, linear, (-) sense, ssRNA
- Multiplication: RA (CYTOPLASM); M (CM)
- Infects: epithelial cells of the respiratory tract
- MOT: respiratory droplets
- Latency: None
- Diseases: URTI, croup, bronchiolitis, pneumonia
Picornavirus
- Family: Picornaviridae
- Virion: naked, icosahedral capsid
- Genomic characteristics: non-segmented, linear, (+) sense, ssRNA
- Multiplication: RAM (CYTOPLASM)
- Infects: oropharynx, GIT, heart, pleura
- MOT: respiratory droplets
- Diseases: Coxsackie virus - enterovirus from New York, HAV - enterovirus causing hepatitis, Poliovirus, Rhinovirus
Retrovirus (HIV)
- Family: Retroviridae
- Genomic characteristics: linear, non-segmented, (+) sense, ssRNA, diploid (presence of DNA and RNA)
- Multiplication: R (NUCLEUS) wherein RNA is transcribed to DNA; AM (CYTOPLASM)
- Infects: CD4+ cells
- MOT: sexual, parenteral
- Diseases: HIV-1 - cosmopolitan distribution; HIV-2 - common in West Africa
Rabies Virus
- Family: Rhabdoviridae
- Virion: enveloped, rod-shaped or bullet-shaped, helical capsid symmetry
- Genomic characteristics: non-segmented, (-) sense, ssRNA
- Multiplication: R (CYTOPLASM); AM (CM)
- Infects: Muscle (initial replication) and neurons
- MOT: infectious saliva, aerosol
- Diseases: Rabies (madness, rage, fury)
HTLV
- Family: Retroviridae
- Genomic characteristics: non-segmented, linear, (+) sense, ssRNA
- Multiplication: R (NUCLEUS) wherein RNA is transcribed to DNA; AM (CYTOPLASM)
- Infects: CD4+ cells
- MOT: sexual, parenteral
- Diseases: HTLV-1, HTLV-2
This quiz covers the types of human influenza, including Type A, B, and C, as well as primary influenza pneumonia and other related diseases. It also explores the concepts of antigenic shift and antigenic drift in the naming of flu viruses.
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