Journal of Vaccines & Vaccination

Abstract

Adaptation of Local Rabies Virus Isolates to High Growth Titer and Determination of Pathogenicity to Develop Canine Vaccine in Ethiopia

Abebe Mengesha Aga, Birhanu Hurisa, Tihitina Tesfaye, Hailu Lemma, Dereje Niguse, Gashaw G/Wold, Amha Kebede, Tsehaynesh Mesele and Kelbessa Urga

Rabies is a zoonotic viral disease which causes acute encephalitis in humans and animals. The case is most severe in developing countries where cell culture derived anti-rabies vaccines are unaffordable or the available nervous tissue-derived vaccines are of questionable immunogenicity and may cause neurological complications. The aim of this research was to adapt local rabies virus isolates on BHK-21 and to study pathogenicity to intramuscular route of inoculation for canine vaccine development. The viruses were isolated from rabid dogs’ brain and human saliva, and adapted to Swiss albino mice brain and cell lines by several blind passages. By titration, a minimum of 106.5TCID50/ml (in vitro) and 104.5MICLD50/0.03 ml (in vivo) virus titer were obtained. For pathogenicity study, mice were inoculated intramuscularly with 250MICLD50/0.1 ml of each adapted virus isolate and observed for 45 days. Only two virus isolates, human origin sululta (HOS) and dog origin (DO) caused 12.5% death. This can show the phylogroup origin of the viruses indicating phylogroup I origin of these virus isolates with decline in virulence. Decline in pathogenicity may be due to adaptation of the viruses to mice brain and cell lines to increase virus infectivity titer. Generally, the exact genetic relationship with fixed rabies virus strain should be studied by molecular techniques and canine anti-rabies vaccine develops from locally isolated viruses.