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ID4 Infectious Diseases
Principles of Microbiology
Toronto Notes 2019
Helical
Icosahedral
Complex
Enveloped Figure 3. Virus morphology
DNA Viruses: Families HHAPPPPy
Hepadnaviradae Herpesviridae Adenoviridae Papillomaviridae Parvoviridae Polyomaviridae Poxviridae
Virology
Viral Basics
• virusesareinfectiousparticlesconsistingofRNAorDNAcoveredbyaproteincoat ■ infect cells and use host metabolic machinery to replicate
■ nucleic acid can be double stranded (ds) or single stranded (ss)
■ can be enveloped or naked
• virionsarematurevirusparticlesthatcanbereleasedintotheextracellularenvironment
• hostsusceptibilityisgovernedbythehostcellandvirussurfaceproteins(viraltropism)andcellular
immunity
Viral Disease Patterns
1. acute infections (e.g. adenovirus)
■ host cells are lysed in the process of virion release
■ some produce acute infections with late sequelae (e.g. measles virus induced subacute sclerosing
panencephalitis)
2. chronic infections (>6 mo): (e.g. HBV, HIV)
■ host cell machinery is used to produce and chronically release virions 3. latent infections
■ viral genome remains latent in host cell nucleus ■ can reactivate (e.g. HSV, VZV)
Table 3. Common Viruses
Nucleic Acid
dsDNA
Enveloped Virus Family
N Adenoviridae
N Papillomaviridae Y Herpesviridae
N Polyomaviridae Y Hepadnaviridae
Poxviridae
N Parvoviridae
N Caliciviridae N Picornaviridae
Y Coronaviridae Y Flaviviridae
Y Togaviridae
Y Retroviridae
Y Arenaviridae
Y Filoviridae
Y Orthomyxoviridae Y Paramyxoviridae
Y Rhabdoviridae
N Reoviridae
Major Viruses
Adenovirus
HPV1,4 HPV6,11 HPV16,18, etc.
HHV1=HSV1 HHV2=HSV2 HHV3=VZV HHV4=EBV HHV5=CMV HHV6* HHV8=KSHV
JC virus
Hepatitis B Variola
Parvovirus B19
Norwalk Hepatitis E
Poliovirus Echovirus Rhinovirus Coxsackie virus Hepatitis A
Coronavirus
Yellow fever Dengue fever Hepatitis C West Nile Zika
Rubella Chikungunya
HIV HTLV-1
Lassa
Ebola, Marburg Influenza A, B, C
Measles Mumps Parainfluenza RSV
Rabies
Rotavirus
Medical Importance
URTI Conjunctivitis Gastroenteritis
Plantar warts
Genital warts
Cervical/anal dysplasia and cancer
Oral, ocular, and genital herpes; encephalitis Genital, oral, and ocular herpes; encephalitis Chicken pox, shingles
Mononucleosis, viral hepatitis
Retinitis, pneumonitis, hepatitis, encephalitis Roseola
Kaposi’s sarcoma, multicentric Castleman’s disease, body cavity lymphoma
Progressive multifocal leukoencephalopathy
Hepatitis Smallpox
Erythema infectiosum (Fifth disease)
Gastroenteritis Acute hepatitis
Poliomyelitis
URTIs, viral meningitis
URTIs
Hand-foot-and-mouth, viral meningitis, myocarditis Acute hepatitis
URTIs, SARS, MERS
Yellow fever
Dengue fever
Hepatitis
Encephalitis, flaccid paralysis Zika virus disease
Rubella (German measles) Chikungunya
AIDS
T-cell leukemia and lymphoma
Lassa fever Hemorrhagic fever Influenza
Measles
Mumps
URTIs, croup, bronchiolitis Bronchiolitis, pneumonia
Rabies
Gastroenteritis
ssDNA (+) ssRNA
(+) ssRNA-RT
(+) ssRNA
dsRNA
Note: ___viridae = family, ___virus = genus, # = species (e.g. Retroviridae HIV-2) *Roseolovirus, Herpes lymphotropic virus
© Beatrice Lau 2011