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Prepared by Perlie Harriet Mata, RMT
Small size: 0.01 -0.3 um FILTERABLE AGENTS Virion- viral particle Capsid – protects the viral nucleic acid
Virion- the whole viral particle, that is the neocapsid w/ its outer envelope (if present)
1. Capsid – protein coat of a virus; made of of numerous capsomere
2. Nucleocapsid- the complex of protective protein and viral nucleic acid
They possess only one nucleic acid: Either DNA/RNA (NEVER BOTH)
a. Helical- rod shaped b. Icosahedra – cube like c. complex- non conforming symmetry
1. Type of nucleic acid
2. Number of strands of nucleic acid and their physical construction (single or double stranded, linear or circular, circular w/ breaks, segmented)
3. Polarity of the viral genome – RNA viruses in w/c the viral genome can be used directly as messenger RNA are by convention termed “positive-stranded” and those for which a transcript has first to be made are termed “negative stranded”
4. The symmetry of the nucleocapsid 5. Presence or absence of a lipid envelope
w/o outer membrane – non-enveloped/ naked resistant to ether ether stable
w/ outer membrane – enveloped sensitive to ether ether labile labile viruses Enveloped – derived from nuclear
membrane or host cell Composed of Lipid Soluble to ether because of
thelipid component
I. DNA viruses – replicates in the nucleus
*dsDNA *icosahedral
Parvoviridae – ssDNA
All are icosahedral symmetry except for Poxviridae – Complex; replicates in the cytoplasm
Pox viridae – Largest virus complex symmetry
ENVELOPED: Hepadnaviridae, Herpesviridae, Poxviridae
NAKED: Papovaviridae, Adenoviridae, Parvoviridae
ssRNA except Reoviridae : dsRNA
Helical except Picornaviridae, Caliciviridae, Reoviridae, Togaviridae, Flaviviridae : Icosahedral
Enveloped except Picorna, Caliciviridae, reoviridae : Naked
Replicates in the Cytoplasm except Retroviridae, Orthomyxoviridae : Nucleus
Storage: 4°C Transport medium: -70°C
1. Light microscopy
Viral inclusions Negri bodies – inclusion in Rabies virus –
cytoplasm
2. Electron Microscopy
Most rapid way of detecting viral infection Most common rapid EM method: Negative
staining
3. Culture a. Chick embryo b. Tissue culture Medium A549 cells – lung carcinoma HeLa cells – cervical carcinoma Hep2 cells – human epithelial cells from laryngeal
carcinoma Human Fibroblast Cells– preferred tissue culture medium
for CMV ** We do not look for colonies, we look for CHARACTERISTIC CPE
CPE (cytophatic effect) – morphological change in cells associated w/ viral proliferation
4. SERO Test:
Neutralization Complement fixation test Hemagglutination Inhibition (Abs against
influenza/ rubella)
BSL1 Non pathogenic for healthy individuals
B. subtilisM. gordonae
BSL2 Common agents of infectious disease including HIVEither result of bioterrorism/ natural method
B. anthracisY. pestis
BSL3 Organism grown in large quantities
Culture for MTBSystemic Fungi (Mold form)Francisella tularensisBrucella spp.
BSL4 ArboviridaeArenaviridaeFilovirus (Ebola virus)Small pox (last case 1997)
Virus Family
Arthropod – borne viruses
1. Bunyaviridae 2. Flaviviridae 3. Togaviridae
EBV: Infectious mononucleosis Burkitt’s lymphoma Target cell: B cells (CD21) IM: Atypical/ Reactive lymphocytes (Downey
cells) T cells reacting to B cells
infected w/ EBV
infections Toxoplasmosis Rubella CMV Herpes Syphilis
CMV: most common congenital infection
Blood Transfusion (leukocytes)/ organ transplant
CMV aka Salivary Gland Virus > 40 day fever Culture: human fibroblast cells Inclusion: OWL’s eye inclusion
HHV6 and HHV7: Roseola (Exanthem subitum)
6th childhood disease
HHV8: Kaposi’s sarcoma Most common malignancy observed
among AIDS patients
Pa = papilloma virus : WART’s Po = Polyomavirus Va –vacuolating virus of monkey
Parvovirus B-19 Slapped cheek Rash Erythema infection 5th disease
Guarheiri body Vaccinia – cow pox virus Variola major – small pox Variola minor – Alastrim
Caliciviridae: Hepa E- fecal oral route
Water contamination Increased fatality : pregnancy
Coronaviridae – common colds SARS
Yellow viruses **Dengue
Hepa C – most common cause of post transfusion Hepatitis
Hepa C 80% Hepa B <10%
Orthomyxoviridae: Genus influenza Enveloped have spikes Composition of spikes:
hemagglutinin Ag Neuramidase
Infected cell is identified by HEMADSORPTION Abs: Hemagglutination inhibition
a. Measles – rubeola b. mumps c. Parainfluenza d. RSV – respiratory syncytial virus
Smallest RNA virus
Hepa A virus: genus enterovirus type 72 Short incubation heap 15-40 days incubation period Differentiate Enterovirus: Acid resistant Rhinovirus: Acid Sensitive
children: gastritis/ diarrhea adults: asymptomatic *common cause of gastritis and diarrhea in
winter
Reverse trancscriptase: unique enzyme RNA-> DNA Genus: Lentivirus HIV1: AIDS in US and Europe HIV2: AIDS in west Aftrica Target cell CD4+
HTLV I HTLVII – associated with hairy cell leukemia
– Bullet shaped Rabies/ Lyssa virus
Rubella – German
Measles Aka RUBIVIRUS
Pox viridae – Largest virus complex symmetry
Picornavirus - Smallest RNA virus