Microbio Viruses Quiz

Viruses

-Small, acellular, DNA or RNA genome
-Obligate intracellular parasites
-Many types, infect all living organisms
-Most have limited host range specificity
-Difficult to treat clinically

intracellular

Type of nucleic acid, shape, host range, presence/absence of envelope
Assigned common enlish name

-Group I: double-stranded DNA viruses [HPV]
-Group II: single-stranded DNA viruses
-Group III: Double-stranded RNA viruses
-Group IV: (+) sense single-stranded RNA viruses [Coronaviruses]
-Group V: (-) sense single-stranded RNA viruses [Orthomyxoviruses]
-Group VI: Retroviruses [Lentiviruses]
-Group VII: Pararetroviruses

Nucleic acid (can be DNA or RNA, double- or single-stranded)

protein shell

phospholipid envelope, host cell

allow attachment and determine virus' host cell specificity

Virion

Classified as coronavirus, single-stranded RNA

Virus glycoprotein spike (S) must bind to transmembrane Angiotensin-Converting Enzyme 2 (ACE2) receptor on host cells
Virus enters host cell via envelope/membrane fusion

Genome: carries the genetic information necessary for replication of new phage particles
Tail sheath: retracts so that the genome can move from the head into the host cell's cytoplasm
Plate and tail fibers: attach phage to specific receptor sites on the cell wall of a susceptible host bacterium

Lytic: virulent
Lysogenic: temperate

when stress induces excision of phage DNA

Lysogenic cycle

1. cell synthesizes capsid proteins
2. cell replicates phage DNA, DNA is packaged into capsids
3. phage lyses cell, and progeny phages are released

1. Lytic (usually cause acute disease)
2. Latent (usually cause chronic disease)

attatchment using viral spike binding to host cell receptor on membrane
-viral spike ability to bind host receptor determines viral specificity
-host antibodies binding viral spikes can neutralizelock attachment virus, inhibit this step

entry/penetration of viral genome into host cell by endocytosis or fusion of envelope with plasma membrane of host cell

uncoating of nucleic acid via capsid digestion, release of nucleic acid

Lytic: influenza, common cold, rabies, COVID-19, ebola, measles
Latent: herpes simplex virus, HIV

biosynthesis of viral proteins and genomes

virus assembly and maturation

release (virions exit host cell), host cell lysis

viruses bud from host cell during chronic shedding of virions

Acquired Immunodeficiency Syndrome (AIDS)

zoonotic from primates, early 1900's in africa

sub-saharan africa
T

Primarily via sexual contact, also blood contact, vertical mother to child

single-stranded RNA (retrovirus)

RT: converts HIV's RNA genome into DNA
IN: inserts the viral DNA into the host genome
PR: processes viral proteins to form mature, infectious virions

Use spike protein (SUp120) to attach to CD4 receptor and CCR5 co-receptor on T-helper cells, penetrates cell via membrane-envelope fusion, uncoating releases RNA

RNA genome reverse transcribed to dsDNA, integrase integrates DNA into genome as provirus
provirus transcribed into viral genomes and viral mRNAs, mRNAs translated into viral pre-protein
Viral pre-protein cleaved into mature proteins by HIV protease, virus assembles, buds from, eventually lyses T-helper host cell

strong initial immune response followed by long chronic phase (9-12 years)

leads to opportunistic infections, onset of acute AIDS disease
death typically from opportunistic infections or cancer

1. Reverse transcriptase inhibitors
2. Protease inhibitors
3. Fusase
4. Integrase

reduces viral replication, prevents drug resistance, improves immune system function, delays disease progression, reduces transmission, long-term suppression

pre-exposure prophylaxis

hemgglutinin (H), neuraminidase (N)

by H and N combination

antigenic drift, antigenic shift

antigenic drift

antigenic shift