Exam 2 - Family: Poxviridae Flashcards
Two subfamilies
Chordopoxvirinae (poxviruses of vertebrates) and Entomopoxvirinae (poxviruses of insects)
8 Genera in the subfamily Chordopoxvirinae
- Genus: Orthopoxvirus
- Genus: Parapoxvirus
- Genus: Avipoxvirus
- Genus: Capripoxvirus
- Genus: Leporipoxvirus
- Genus: Suipoxvirus
- Genus: Molluscipoxvirus (Myxoma virus)
- Genus: Yatapoxvirus (Yaba Monkey Tumor Virus)
Properties of Poxviruses
- Large, sometimes enveloped doubled stranded DNA viruses.
- Pleomorphic, brick shaped Possess an irregular surface of projecting tubular or globular structures
- Do not conform to icosahedral or helical symmetry.
Genus: Parapoxvirus properties
Ovoid, covered with long thread-like surface tubules, arranged in crisscross fashion, resembling a ball of yarn.
Two distinct infectious poxvirus particles exists
Intracellular Mature Virus (IMV) and Extracellular Enveloped Virus (EEV)
Extracellular Enveloped Virus (EEV)
Contains two membranes: envelope and inner membrane. Are released by budding that contain virus encoded proteins from host cells membrane.
Intracellular Mature Virus (IMV)
Only have an inner membrane. Come out by disruption of host cell and have only inner membrane.
Poxvirus Replication
Occurs in cytoplasm. Unlike other DNA viruses, poxviruses have evolved to encode the enzymes required for transcription and replication of the viral genome.
Poxvirus Antigenic Characteristics
Group-specific Nucleoprotein (NP), genetic recombination among the viruses
Poxvirus Stability
Unlike other enveloped viruses, there is high environmental stability and remain infectious. Less sensitive to organic solvents/disinfectants due to low lipid content. High resistance of drying. Can survive for many months and years in dried scabs.
Poxvirus Transmission - Skin
Only with broken or lacerated skin.
Poxvirus Transmission - Respiratory route
Aerosol route, typically most common route
Poxvirus Transmission - mechanical
Biting of arthropods
Poxvirus Pathogenesis and Immunity
Are highly epitheliotropic. Can cause systemic diseases, and are host specific.
Spread of Poxvirus
Gains access to the systemic circulation via the lymphatic system. Secondary viremia disseminates the virus back to the skin.
Chronological pathway of skin lesions poxvirus
Macule, Papule, Vesicle, Pustule, Ulcer, Scab
Ma- Pa-Ve-PuU-Sca
Genus: Orthopoxvirus
Cowpox in cattle, cats and humans; Monkeypox
Cowpox Distribution
Endemic only in Europe and Asia.
definition of endemic: regularly found among particular people or in a certain area
Cowpox Reservoir
Rodents
Cowpox in Cattle - Transmission
From cow to cow, infected milker’s hands or contaminated teat cups
Cowpox in Cattle - Incubation Period
3-7 days
Cowpox in Cattle - Clinical Findings
Papular lesions appear on the teats and udder or in mouths of suckling calves.
Cowpox in Cats - Transmission
Typically through bite or skin wound. Most commonly from rodents. Can be oro-nasal route.
Cowpox in Cats - Clinical signs (Primary Lesions)
Single primary lesion usually on head, neck or forelimb
Cowpox in Cats - Clinical signs (Secondary Lesions)
7-10 days after primary lesion, develop into discrete, circular, ulcerated papules. May develop mild coryza or conjunctivitis.
Cowpox in Humans - Transmission
Direct contact with cats, rarely from cattle.
Cowpox in Humans - Clinical signs
Macropapular lesions on hands and face. Enlarged painful local lymph nodes, some may report fever, vomiting, and sore throat.
Monkeypox in Humans - Symptoms
Similar to smallpox
Monkeypox in Humans - Transmission (primary)
Results from direct contact with blood, bodily fluids, or rashes of infected animals.
Monkeypox in Humans - Transmission (secondary)
Results from close contact with infected respiratory tract excretions, with the skin lesions of an infected person or with recently contaminated objects.
Monkeypox - Distribution
Villages in Central and West Africa
Monkeypox - invasion period
(0-5 days) Fever, intense headache, lymphadenopathy, muscle pain
Monkeypox - Skin eruption period
Evolution of the rash from maculo-papules to vesicles, pustules, followed by crusts.
Monkeypox in Monkeys
The disease in characterized by generalized skin eruptions, developing to papules on the trunk, face palms and soles.