Isolation and Identification of Arboviruses from the Sultanate of Oman
Arboviruses are the name given to arthropod-borne viruses that are transferred by invertebrate animals (arthropods). Scholars are increasingly interested in this subject as it can help the treatment of animals who suffer from these viruses.
In the Oman, sentinel herds and a vector surveillance system were used to recognize the existence of arboviruses. Two strains of bluetongue virus (BTV) serotype 4 and two strains of Akabane virus, were isolated and identified; the BTV viruses were from goats while the second Akabane isolate came from Culicoides imicola, a midge. This was the first isolation of an Akabane virus from Culicoides in Oman.
Before this study, there had been no identification of the presence of Akabane and the bluetongue virus (BTV) in Arabia. The study was designed to monitor arbovirus activity over a 12-month period using a technique that takes “regular sampling of blood and serum from serologically naive animals at intervals of 2-4 weeks. Evidence of virus infection is detected initially by seroconversion. Then, because neutralizing antibodies take approximately 14 days to develop, virus isolation may be attempted from stored whole blood samples taken 2-4 weeks prior to seroconversion. Accordingly it was planned to collect blood samples from sentinel animals on a monthly basis”.
The scholars chose 34 farms either along the Batinah Coast to Rostaq (near Nakhal) in Northern Oman or at Salalah in Southern Oman. At least 10 animals were picked and identified by ear-tagging, mostly goats. Monthly bleeding was carried out from March 1987 to March 1988 but whole blood for virus isolation work was amassed only during January – March 1988. The “heparinized blood was centrifuged at 3000 g for 10 min and washed three times with normal saline before an equal volume of OPG (0-5% w/v potassium oxalate, 0-5 % w/v phenol, 50 % v/v glycerine and 50 % distilled water) was added. The mixture was stored at +4 C until transportation on wet ice to Institute for Animal Health, Pirbright [Woking], England”.
The study allowed scholars to come to the conclusion that these midges are probably a key vehicle of these arboviruses in the Arabian Peninsula, although it is highly unlikely that the C. imicola is the only important arbovirus vector in Oman.
Al-Busaidy, S. M. & Mellor, P. S. (1991) Isolation and Identification of Arboviruses from the Sultanate of Oman, Epidemiology and Infection, Cambridge University Press.