Seroprevalence of five bovine arboviruses and development of inactivated trivalent vaccine for Aino, Akabane and Chuzan viruses in Korea

Abstract

Arthropod-borne viruses (arboviruses) are transmitted by blood-sucking arthropods, such as mosquitoes, Culicoides biting midges and ticks. These arbovirus infections are mainly associated with abortion, stillbirth and congenital defects in pregnant cattle, sheep and goats, which induces a considerable economic loss in livestock industry. To investigate the possible circulation of arboviruses in South Korea, nationwide surveillance of five arbovirues was conducted in sentinel calves during 2009?2012. We used serum neutralization tests to investigate the presence of antibodies for the Aino virus, Akabane virus, bovine ephemeral fever virus, Chuzan virus and Ibaraki virus. In 2009, 2011 and 2012, the seropositive rates for these five arboviruses were all less than 14.1%. In 2010, however, the seropositive rates for Aino virus and Akabane virus were 33.2% and 40.2%, respectively. High seropositive rates were also associated with a large-scale outbreak of Akabane viral encephalomyelitis in cattle in southern Korea in 2010. Continued seroprevalence surveillance will be useful for monitoring natural arboviral diseases. The arboviruses seem to be widely distributed in Southeast Asia and Australia. Among the arboviruses, Aino, Akabane and Chuzan viruses are respectively isolated in abortion cases. As a control strategy, an inactivated trivalent vaccine against Aino, Akabane and Chuzan virus was developed by using binary ethylenimine or formalin as an inactivating agent. The newly developed trivalent vaccine is evaluated for its safety and immunogenicity in animals such as mice, guinea pigs and cattle. The immune responses were significantly detected within 2-weeks after second vaccination without any side effects. Since the field application of experimental vaccine also revealed increased antibodies in inoculated cattle, we demonstrated that these trivalent vaccines could be used as a vaccine to control the arboviral infections in ruminants. This study approached the seroprevalence of five arboviruses in sentinel cattle and development for prevention of the diseases on Aino, Akabane and Chuzan viruses in cattle.