Abstract:
INTRODUCTION : Culicoides biting midges (Diptera: Ceratopogonidae) are
vectors of arboviral pathogens that primarily affect livestock represented by
Schmallenberg virus (SBV), epizootic hemorrhagic disease virus (EHDV) and
bluetongue virus (BTV). In Kenya, studies examining the bionomic features of
Culicoides including species diversity, blood-feeding habits, and association
with viruses are limited.
METHODS : Adult Culicoides were surveyed using CDC light traps in two semiarid
ecologies, Baringo and Kajiado counties, in Kenya. Blood-fed specimens
were analysed through polymerase chain reaction (PCR) and sequencing
of cytochrome oxidase subunit 1 (cox1) barcoding region. Culicoides pools
were screened for virus infection by generic RT-PCR and next-generation
sequencing (NGS).
RESULTS : Analysis of blood-fed specimens confirmed that midges had fed
on cattle, goats, sheep, zebra, and birds. Cox1 barcoding of the sampled
specimens revealed the presence of known vectors of BTV and epizootic
hemorrhagic disease virus (EHDV) including species in the Imicola group
(Culicoides imicola) and Schultzei group (C. enderleni, C. kingi, and
C. chultzei). Culicoides leucostictus and a cryptic species distantly related
to the Imicola group were also identified. Screening of generated pools
(11,006 individuals assigned to 333 pools) by generic RT-PCR revealed
presence of seven phylogenetically distinct viruses grouping in the genera
Goukovirus, Pacuvirus and Orthobunyavirus. The viruses showed an overall
minimum infection rate (MIR) of 7.0% (66/333, 95% confidence interval (CI)
5.5-8.9). In addition, full coding sequences of two new iflaviruses, tentatively
named Oloisinyai_1 and Oloisinyai_2, were generated by next-generation sequencing (NGS) from individual homogenate of Culicoides pool.
CONCLUSION : The results indicate a high genetic diversity of viruses in Kenyan
biting midges. Further insights into host-vector-virus interactions as well as
investigations on the potential clinical significance of the detected viruses
are warranted.
