Final Exam - Picornaviridae Flashcards
Two important genera of Picornaviridae
Aphtovirus and Enterovirus
Picornaviridae Replication
Poliovirus does not enter cells through endocytosis.
Enterovirus
Cause of Swine Vesicular Disease and Polioencephalomyelitis.
Swine Vesicular Disease Virus (SVDV)
Enzootic in Italy. Resistant to ambient temperature and to sodium carbonate. Transmitted in pork products. Not found in NA/USA and is an FAD.
SVDV Transmission
Virus infects swine via skin abrasions and mucosa by ingestion and inhalation. Direct contact among infected swine or with their excretions.
SVDV Clinical Features
Sudden appearance of lameness. Vesicles appear at the junction between the heel and coronary band. Lesions on snout, lips and tongue. Some develop encephalomyelitis.
SVDV Pathogenesis
Infection through fecal-oral route. Replication is in the GIT. Skin abrasion may act as portals of entry. Particularly feet. Viremic within 24 h.
SVDV Diagnosis
Case should be treated as FMD. RT-PCR multiplexed assays which can detect multiple agents at once. ELISA if vesicular fluid is collected. Virus isolation in swine kidney cells.
SVDV Vaccine
THERE IS NO VACCINE!
Foot and Mouth Disease Virus (FMDV)
Picornaviridae, Aphthovirus. Not cross protective. A disease of cloven hoofed animals.
FMDV Clinical Signs
Fever, excess salivation, nasal discharge (cattle). Initially vesicles on buccal areas, coronary bands and interdigital space. Recover in two weeks unless secondary infections arise.
FMDV Clinical Signs in Sheep and Goats
Mild, if any, signs.
Why care about FMD?
Highly contagious. Loss of livestock production cause economic loss. Limitation of international trade in livestock and animal products.
FMDV Transmission
Respiratory aerosols, direct contact and indirect contact via fomites.
Sheep = maintenance host and carrier for 4-6 mo. Pigs = amplifier host and is not a carrier Cattle = indicator host and is a carrier for 6-24 mo.
FMDV Diagnosis
Virus isolation and identification (vesicular fluid). Antigen or nucleic acid detection. Complement fixation, ELISA and virus neutralization.
FMDV Sample Collecting for Testing
Authorities should be contacted before collecting. Notify authorities and wait for instructions before collecting samples. Sample-s are sent under secure conditions and to authorized laboratories.
FMDV Treatment
There is no treatment available. Outbreak results in quarantine, euthanization, and disposal. Vaccines are available.
FMDV Disinfection
Effective solutions include: 2% sodium hydroxide (lye). 4% sodium carbonate (soda ash), 5.25% sodium hypochlorite (household bleach), 0.2 citric acid. Areas must be free of organic matter.
FMDV - Vaccination
Killed vaccine, serotype specific. Used to control outbreak. Will have to have annual revaccination. Does not protect against infection with other serotypes.
