Short communication. Bluetongue virus serotype-1 in goats in the Pithoragarh area of Uttarakahand, India

This short communication reports the results of a bluetongue sero-surveillance conducted in the Pithoragarh hills of Uttarakhand in India during the autumn of 2011. Unclotted blood and serum samples were collected from 51 goats for detection of bluetongue virus (BTV) antigen and antibodies. Of the 51 collected samples, 18 (35%) were positive to an indirect ELISA and 33 (64%) resulted positive to a BTV ELISA antigen. From a strong antigen-positive blood sample, a BTV was isolated (named as PTG-13) on cell culture and was subsequently confirmed as BTV‑1 by RT‑PCR and partial sequencing of genome segment-2. The goat serum samples were found to contain high titer of neutralising antibodies against BTV-23, nonetheless the virus could not be isolated. Interestingly, no neutralizing antibodies were detected against PTG-13 or other BTV-1 isolate, which suggests that sampling was probably done before the development of neutralizing antibodies against PTG-13 virus in the host. Isolation of BTV-1 (PTG-13) and presence of BTV-23 neutralizing antibodies in serum samples indicate that goats were probably infected with BTV-1 and 23 in different periods

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

Surveillance of bluetongue virus antibody in goats using a recombinant VP7-based indirect ELISA in the coastal saline area of West Bengal, India

The authors describe the serological surveillance of bluetongue virus (BTV) group-specific antibody in goats of the coastal saline (Sunderban) area of West Bengal, India. A recombinant viral protein 7 (rVP7)-based indirect enzyme-linked immunosorbent assay (ELISA) was used to detect the antibody in sera. The bacterially expressed rVP7 was purified by affinity chromatography. The diagnostic performance of the assay was assessed by comparing it to the commercially available previously validated competitive ELISA. Using the control and 1 202 test sera, the cut-off value, sensitivity and specificity as well as other performance characteristics e.g. the Youden index, efficiency, positive and negative predictive value and prevalence were estimated. Field-collected goat sera (n = 1 202) were tested and a serological prevalence rate of 47% was observed in the study area

Genetic and phylogenetic analysis of the outer capsid protein genes of Indian isolates of bluetongue virus serotype-16

Aim: The aim of the study was to characterize bluetongue virus serotype 16 (BTV-16), recently isolated from different states of India. The evolutionary relationship of newly isolated BTV-16 and previously reported Indian and global BTV-16 isolates were compared using molecular analysis. Materials and Methods: In the present study, five (n=5) BTV-16 isolates were used to amplify gene segment-2 and segment-6 encoding the outer capsid proteins VP2 and VP5, respectively. The amplified products were purified and sequenced by the Sanger sequencing method. The phylogenetic relationship and nucleotide identity of all five BTV-16 isolates were compared with previously reported Indian and global BTV-16 isolates. Nucleotide sequence data were aligned using the CLUSTAL W algorithm implemented in the MegAlign of DNASTAR program package (MegAlign 5.00, DNASTAR Inc., Madison, USA). Phylogenetic analyses were carried out using MEGA version 6.0 software with the best nucleotide substitution model. Results: Phylogenetic analysis based on the VP2 and VP5 encoding genes, segregates Indian BTV-16 isolates in a distinct cluster with proximity to the Eastern topotype. Indian isolates make a monophyletic cluster with Eastern topotypes with Western topotype BTV-16 (BTV-16/NIG/AJ586694) occupying a separate cluster. Indian isolates were found to share 91.5%- 97.5% and 96.5%-98.9% identity at the nucleotide and deduced amino acid (aa) level, respectively, to the global BTV-16 isolates. There is a high degree of variation with the Nigerian isolate with 27.0-27.7% and 26.0-26.9% at the nucleotide and aa sequence level, respectively. These data suggest that Indian BTV-16 isolates might have evolved separately within the Eastern BTV topotype. Conclusion: Phylogenetic analyses and nucleotide identity of BTV-16 isolates at the VP2 and VP5 gene encoded level indicate that isolates used in the present study might have evolved from a common Eastern topotype ancestor. The data presented in this study will be helpful for future selection of reference strains in a serological and molecular epidemiology study