Segment-2 sequencing and cross-neutralization studies confirm existence of a neutralization resistant VP2 phenotypic variant of bluetongue virus serotype 1 in India.

Segment-2 (seg-2) of a bluetongue virus seropype-1 (BTV-1) isolate WGV104/08/Ind of Indian origin was sequenced and its neutralization behavior was studied to understand the antigenic similarity and relationship with other BTV-1 isolates. Multiple alignments of the coding region of seg-2 of WGV104/08/Ind revealed 97.6-99.0% and 97.2-98.4% similarity with other Indian BTV-1 isolates at nucleotide and deduced amino acid sequence level respectively. Several conservative and non-conservative substitutions were observed on the deduced VP2 amino acid sequence of WGV104/08/Ind. Non-conservative substitution of Lys119Glu on the B-cell epitope and Arg330Gly on the neutralizing epitope of VP2 of this isolate was observed. Using isolate-specific heterologous hyperimmune serum (HIS) the phenotypic antigenic relationship (r) was determined between WGV104/08/Ind and other Indian BTV-1 isolates which ranged from 0.092 to 0.208. The relationship score ranged from 0.203 to 0.295 when neutralization behavior of other Indian BTV-1 isolates was studied with the HIS of WGV104/08/Ind. Antigenic similarity (R) between WGV104/08/Ind and other Indian BTV-1 isolates was estimated from a reciprocal cross-neutralization study and ranged from 14.70% to 24.80% indicating existence of major subtype antigenic divergence and neutralization resistant behavior of WGV104/08/Ind.

Detection of fowl poxvirus integrated with reticuloendotheliosis virus sequences from an outbreak in backyard chickens in India.

Fowl poxvirus (FPV) infection was observed in unvaccinated backyard chickens. A total of 15 birds were affected in a flock of 37. Pock lesions were observed on the comb, eyelids, beak and wattles. The birds appeared sick with roughened feathers and stunted growth. No mortality was recorded. DNA was isolated from scabs and polymerase chain reaction (PCR) was performed to amplify the 4b core protein gene of FPV, the envelope (env) gene of reticuloendotheliosis virus (REV) and the region of FPV flanking REV 5´ long terminal repeat (LTR). Correct-size PCR products of 578 bp, 807 bp and 370 bp, respectively, were observed in agarose gel electrophoresis. Sequence analysis of these products suggests that the virus was an FPV with a genome containing an integrated near full-length REV provirus. Given the fact that REV has been associated with immunosuppression, its presence in the genome of FPV appears to play an important role in the pathogenesis of fowl pox and presumably prolongs persistence of FPV in bird populations. In the present case, fowl pox has been observed to have persisted for about three years in fowl that were reared in backyard systems in villages.