Molecular detection and characterization of bovine viral diarrhea virus type 2 and bluetongue virus 9 in forest flies (Hippobosca equina) collected from livestock in southern Kazakhstan

Abstract

Keds are hematophagous ectoparasites of animals belonging to the family Hippoboscidae (Diptera: Hippoboscoidea). Because of their importance as vectors of some pathogens of medical and veterinary importance, they have received special attention. There are numerous studies demonstrating the presence of various parasites and pathogenic bacteria in keds. At the same time, there are very few reports on ked-related viruses. The aim of this study was to perform a molecular survey of viral pathogens in the forest fly (Hippobosca equina) from southern Kazakhstan. In this study, 104H. equina were collected from livestock in Turkistan oblast (southern region of Kazakhstan), which has the largest concentration of livestock in the country. Insect homogenates were screened by PCR for pestiviruses, orbiviruses, flaviviruses, orthobunyaviruses, phleboviruses, orthopoxviruses, capripoxviruses, parapoxviruses, and asfiviruses. The causative agents of two livestock diseases, bovine viral diarrhea virus (BVDV) (3/104; 2.88%; 95% confidence interval (CI): 0.6-8.2%) and bluetongue virus (BTV) (1/104; 0.96%; 95% CI: 0.02-5.24%), were identified and subjected to further analysis. The BTV strain was isolated and all ten genomic RNA segments were sequenced using the Sanger technique. The isolated BTV strain showed >99.6% identity in all genomic segments with the BTV-9 strains belonging to the 'western' topotype. Partial analysis of the 5'-untranslated region demonstrated that both BVDV strains are closely related to Pestivirus B. Flaviviruses, phleboviruses, orthobunyaviruses, poxviruses, and asfiviruses were not detected. This is the first report describing BVDV type 2 in Kazakhstan. The study also confirms the presence of BTV serotype 9 in southern Kazakhstan. The data presented here can help improve preventive measures to control the spread of viral diseases in livestock by using forest flies as an object of epidemiological studies. However, further studies are needed to investigate the vector capacity of H. equina and its suitability for xenodiagnosis of veterinary relevant pathogens.

Keywords: Bluetongue; Bovine viral diarrhea; Forest fly; Hippobosca equina; Hippoboscidae; Kazakhstan.