Development of real-time RT-qPCR assays for the typing of two novel bluetongue virus genotypes derived from sheeppox vaccine

Previously, we reported the detection of two novel bluetongue virus (BTV) strains (SPvvvv/02 and SPvvvv/03), possibly representing new BTV genotypes, in a batch of sheeppox vaccine. We developed type-specific RT-qPCR assays (targeting genome segment 2) for these two new BTV strains. The limit of detection of both assays was 10 genome copies/mul and no cross-reactivity with other BTV genotypes was observed. The performance of three other BTV group-specific diagnostic assays was also tested against the putative novel genotypes. RT-qPCR assays targeting BTV segment 9 and 10 detected both strains (SPvvvv/02 and SPvvvv/03) whereas a BTV segment 1 RT-qPCR assay was unable to detect either BTV strain. The work presented here expands upon the current repertoire of RT-qPCR assays for BTV genotype determination.