Uncanny Segmental Molecular Integration of Ahsv and Eev with Btv in Sheep and Goats in Egypt

Abstract

African horse sickness (AHS) is caused by a virus of the family Reoviridae, genus Orbivirus. There are 9 antigenically distinct serotypes of AHS virus (AHSV) identified by virus neutralisation, but some crossreaction has been observed between 1 and 2, 3 and 7, 5 and 8, and 6 and 9. No cross-reactions with other known orbiviruses have been observed. Resistance to physical and chemical actionTemperature:AHSV is relatively heat stable, and it is not inactivated by heating in citrated plasma at 55-75°C for 10 minutes, but the virus can be inactivated at 72°C for 120 minutes. Minimal loss of titre when lyophilised or frozen at -70°C with Parker Davis Medium. Infectivity is remarkably stable at 4°C, particularly in the presence of stabilisers such as serum and sodium oxalate, carbolic acid and glycerine: blood in OCG can remain infective >20 years. Can be stored >6 months at 4°C in saline with 10% serum. Fairly labile between -20°C and -30°C. pH:Destroyed at pH < 6 or pH ≥ 12. Optimal pH is 7.0 to 8.5. Chemicals/Disinfectants: Inactivated by formalin (0.1%) for 48 hours, β-propiolactone (0.4%), binary ethyleneimine or radiation. Resistant to lipid solvents such as ether. Inactivated by acetic acid (2%), potassium peroxymonosulfate/sodium chloride -Virkon® S (1%), and sodium hypochlorite (3%). Survival:Putrefaction does not destroy the virus: putrid blood may remain infective for >2 years, but virus is rapidly destroyed in meat by rigor mortis (lowering pH).Vaccine strains survive well in lyophilised state at 4°C. EPIDEMIOLOGY• The disease has both a seasonal (late summer/autumn) and an epizootic cyclical incidence, with disease associated with drought followed by heavy rain. AHSV is capable of overwintering, at least in milder climates where Culicoides adults can survive.