Family: Asfarviridae Flashcards
Properties of Asfarviridae family
Virions are enveloped
Complex icosahedral capsid
Genome consists of a single molecule of linear double-stranded DNA
Replication occurs int he cytoplasm, although host cell nucleus is involved in early stages of DNA replication
Only known DNA arbovirus
African Swine Fever
ASF virus stability
Virus can survive at least 30 days in pens
Very resistant to pH change
Highly resistant to putrefaction
Hemadsorption of ASF virus
Virus does not hemagglutinate however, pig erythrocytes will adhere to the surface of pig monocyte or macrophage cells infected with ASF virus
Hemadsorption is attributed to a virus specific protein that appears on plasma membrane of infected cells during late infection
Vector of ASF
Soft ticks
Virus replicates in the tick resulting in trans-stadial, transovarial, and sexual transmission
Sylvatic cycle of ASF
- reservoir
- transmission
Reservoir = warthog, giant forest hog, bush hog
Transmission between warthogs and soft ticks
Asymptomatic infection in wild pigs
Young pigs develop a viremia with high enough virus titers to infect ticks feeding on them
Domestic cycle of ASF
-transmission
Bite of infected tick; direct contact with infected animal; indirect contact on fomites
Virus spreads when pigs are fed uncooked scraps that contain infected pork
3 primary effects of ASF
Leukopenia
Lymphopenia
Thrombocytopenia
Sites of virus replication of ASF
Pharyngeal mucosa, tonsils
Endothelial cells
Megakaryocytes
Macrophages
Apoptosis of host cells
p54 protein (encoded by virus) directly induces apoptosis of host cells
Peracute clinical signs of ASF
Pigs may die suddenly, or
High fever, hyperpnea, and hyperemia before death
Acute clinical signs of ASF
High fever, anorexia, erythema, respiratory distress, recumbency
Cyanotic skin blotching on the ears, tail, lower legs
Vomiting, diarrhea
Abortion, death
Chronic clinical signs of ASF
Emaciation and stunting
Swollen joints
Ulcers and reddened or raised necrotic skin foci
Pneumonia
Enlarged friable spleen - Blackberry jam spleen
Diagnosis of ASF
Hemadsorption
Immunity of ASF
Infected pigs produce virus specific antibodies however, sera from infected pigs does not neutralize the virus hence the humoral immune response does not have a substantial protective value
Therefore, attempts to develop a vaccine have been unsuccessful
