Virology Flashcards
Nucleic acid genome + capsid =
Nucleocapsid
Attachment to host cell receptors
Surface proteins
For replication
DNA or RNA polymerases
Interaction between nucleocapsid and envelope
Matrix protein
Evasion of host defenses
Antigenic (serotypic) variants
Lipid membrane derived from host cell
Viral envelope
Viral envelope is acquired as the virus exits from the cell in a process called
Budding
All enveloped viruses acquire their envelope from plasma membrane EXCEPT
Herpesvirus
True or False: Enveloped viruses are less stable and more easily inactivated
True
Naked Viruses
CaliciPicornaReoParvo AdenoPapillomaPolyoma
Purified nucleic acids of most dsDNA and (+) strand genome ssRNA viruses are ________?
Infectious
dsDNA of Poxviruses and HBV
Not infectious
Naked nucleic acids of (-) strand ssRNA and dsRNA viruses are _____?
Not infectious
Infectious particles composed entirely of protein which cause transmissible spongiform encephalopathies
Prions
Non-pathogenic prions
Alpha helix
Pathogenic prions
Beta-pleated sheet
All viruses are haploid EXCEPT
Retroviruses
Segmented Genome Viruses
BunyavirusesOrthomyxovirusesArenavirusesReoviruses
Negative strand RNA viruses
ArenavirusesBunyavirusesParamyxovirusesOrthomyxovirusesFilovirusesRhabdoviruses
Causes epidemics
Genomic reassortment
One virus produces a protein that can be used by another virus
Complementation
Two different viruses infect the same cell
Phenotypic mixing
Viral Growth Curve: A single virus particle infects a cell
Phase 0: Entry
Viral Growth Curve: Virus decreases in number but continues to function
Phase 1: Decline
Viral Growth Curve: No virus is detectable inside the cell
Phase 2: Eclipse Period
Viral Growth Curve: Dramatic increase in amount of detectable viruses
Phase 3: Rise Period
Viral Growth Curve: Amount of detectable viruses reaches a plateau
Phase 4: Latent Period
Viral Growth Curve: Marked derangement of cell function leading to lysis and cell death; Remarkable amplification in number of viral particles
Phase 5: Cytopathic Effect
Visual or functional change in infected cells
Cytopathic effect
Oncogenic viruses induce transformation and unrestrained growth
Malignant transformation
Infected cells appear normal, but are producing large numbers of progeny viruses
Commensal symbiosis
Bind cytokines and block their ability to interact with receptors on their intended targets
Cytokine decoys
Reduce the expression of antigen presenting cells and inactivate complement
Virokines
Produce virus for long periods of time; Can serve as a source of infection for others
Carrier state
Not producing virus at the present but can be reactivated at a subsequent time
Latent infections
Long incubation period, often measured in years
Slow virus infections
Attachment of RBCs to surface of infected cells
Hemadsorption
Interference with CPE by another virus
Interference
Finding antibody in one who previously had none
Seroconversion
Can be used to diagnose current infection
Presence of IgM
Cannot be used to diagnose current infection; Detect past or chronic infection
Presence of IgG
Gold Standard in Viral diagnosis
Presence of viral DNA or RNA
Induce humoral and cell-mediated immunity but may revert to virulence on rare occasions; Dangerous to give to immunocompromised patients or their close contacts
Live-attenuated Vaccines
The only live-attenuated vaccine that can be given to HIV (+) patients
MMR
Live-attenuated Vaccines
Yellow feverVaricella zosterSabin’s PolioMMR
Induce only humoral immunity but are stable
Killed vaccines
Killed Vaccines
RabiesInfluenzaPolio (Salk’s)Hepatitis A
Recombinant Vaccines (Synthetic)
Hepatitis B (recombinant HBsAg)HPV (types 6,11,16,18)
DNA viruses
HepadnaHerpesAdenoPoxParvoPolyomaPapilloma
All DNA viruses have double-stranded DNA EXCEPT
Parvovirus (single-stranded)
All DNA viruses have linear DNA EXCEPT
PapillomaPolyomaHepadna
All DNA viruses are icosahedral EXCEPT
Poxvirus
All DNA viruses replicate in the nucleus EXCEPT
Poxvirus
Mode of Transmission: Parvovirus B19
RespiratoryTransplacental
Mode of Transmission: Adenovirus
RespiratoryFecal-oral
Mode of Transmission: Human Papillomavirus
SexualSkin contact
Naked virus with icosahedral symmetry; Single stranded DNA genome; One serotype; Transmission: respiratory droplets and transplacental
Parvovirus B19
Bright red cheeks (slapped cheeks) with fever, coryza and sore throat
Erythema infectiosum (Fifth Disease)
Transient but severe aplastic anemia in children; Sickle cell anemia, Thalassemia, Spherocytosis
Aplastic Crisis
Pancytopenia in immunodeficient patients
Chronic B19 Infection
Naked viruses with double-stranded linear DNA and an icosahedral nucleocapsid; Only virus with fiber; 41 antigenic types; Transmission: aerosol droplet, fecal-oral, direct contact
Adenovirus
Spectrum of Disease of Adenovirus: URT
PharyngitisConjunctivitisCoryza
Spectrum of Disease of Adenovirus: LRT
BronchitisAtypical Pneumonia
Spectrum of Disease of Adenovirus: GIT
Acute Gastroenteritis
Spectrum of Disease of Adenovirus: GUT
Hemorrhagic cystitis (Cowdry type B intranuclear inclusions)
Most common cause of Pediatric Viral Gastroenteritis?
Rotavirus
Naked viruses with double-stranded circular DNA and an icosahedral nucleocapsid; at least 100 types; Transmission: direct contact or sexually
Human Papilloma Virus
Infect squamous cells and induce formation of cytoplasmic vacuole
Koilocytes
Encode proteins that inactivate tumor suppressor genes
Genes E6 and E7
Skin and plantar warts
HPV 1-4
Genital warts and respiratory tract papillomas; Most common viral STD
HPV 6-11
Carcinoma of cervix, penis, and anus
HPV 16, 18, 31, 33
Gold Standard for diagnosis of HPV
PCR
Treatment for Genital warts
Podophyllin
Treatment for Skin warts
Liquid nitrogen
Treatment for Plantar warts
Salicylic acid
Only causes disease in immunocompromised hosts; Causes progressive multifocal leukoencephalopathy (PML) in pts with AIDS
JC Polyoma Virus
Most common Demyelinating disease
Multiple sclerosis
Only causes disease in immunocompromised hosts; Causes hemorrhagic cystitis and nephropathy in patients with solid organ and bone marrow transplants
BK Polyoma Virus
Most common cause of Adult Viral Gastroenteritis?
Norwalkvirus
Herpes Viruses
CMVHSVEBVVZV
Enveloped virus with icosahedral nucleocapsid and linear double-stranded DNA; Multinucleated giant cells on Tzanck smear; Large, pink to purple intranuclear inclusions (Cowdry type A)
Herpes Simplex Viruses
Transmission of HSV 1
Saliva or direct
Transmission of HSV 2
Sexual or transvaginal
Site of latency of HSV 1
Trigeminal ganglia
Site of latency HSV 2
Lumbosacral ganglia
Spectrum of Disease of HSV 1
GingivostomatitisHerpes labialis (lips)KeratoconjunctivitisTemporal lobe encephalitisHerpetic whitlow (fingers)Herpes gladiatorum (trunk)
Spectrum of Disease of HSV 2
Genital herpesNeonatal herpesAseptic meningitis