Genetic variety of bovine viral diarrhea virus 1 strains isolated from sheep and goats in India.

UNLABELLED: Antigenic and genetic typing of pestiviruses isolated from Indian sheep and goats was carried out. Testing of 1777 sheep and 1026 goat blood samples collected between 2004 and 2008 resulted in isolation of twelve pestiviruses, seven from sheep and five from goats. All of them were antigenically typed as bovine viral diarrhea virus 1 (BVDV-1). Both the partial 5ʹ-UTR and entire non-structural autoprotease (Npro) gene of the pestiviruses were amplified by RT-PCR and sequenced. The phylogenetic analysis confirmed all twelve sheep and goat pestiviruses as BVDV-1 and they were further classified into two subtypes, BVDV-1b (seven) and BVDV-1c (five). This is for the first time that BVDV-1c was detected in sheep and goats. However, no association between the subtype and geographic area of origin was observed. Although closely related, BVDV-1b and BVDV-1c isolates of sheep and goats were placed in a different clade than previously reported Indian BVDV-1b/BVDV-1c isolates. This study confirmed widespread prevalence of BVDV-1 in Indian sheep and goats that has significance in the epidemiology of bovine viral diarrhea. KEYWORDS: bovine viral diarrhea virus; BVDV-1; goat; Npro; genetic typing; sheep; 5ʹ-UTR.

Genetic and antigenic characterization of bovine viral diarrhea virus type 2 isolated from Indian goats (Capra hircus).

Recent studies have shown that bovine viral diarrhea virus (BVDV) type 1 is widely prevalent in Indian cattle. In a surveillance of randomly collected 562 blood samples from seven states during 2004-2006, BVDV type 2 was detected in two native Indian goats by nested reverse transcription polymerase chain reaction (nRT-PCR). The virus isolated from them was classified antigenically as BVDV 2 on the basis of virus neutralization test and reactivity with monoclonal antibodies. Phylogenetic analysis of three different genomic regions, 5' un-translated region (5' UTR), E(rns) structural coding region and NS5B nonstructural coding region typed Indian goat isolate as BVDV 2a having close similarity with strains from North America and Europe suggesting its probable introduction through trade. It was placed in a separate clade within the 2a branch having unique mutations in E(rns) and NS5B region. This is the first report of BVDV 2 in India and only second time recorded in goat species. The isolation of BVDV 2 from goat warrants intensive surveillance in cattle and sheep.

Pathogenicity of an Indian isolate of bovine viral diarrhea virus 1b in experimentally infected calves.

The aim of this study was to determine the pathogenicity of an Indian bovine viral diarrhea virus (BVDV) 1b isolate in 7-9-months-old male calves. Infected (four) and control (two) calves were bled at three days interval for hematological, virological and serological studies until day 27. All infected calves developed respiratory illness, biphasic pyrexia, mild diarrhea, leucopenia and mild thrombocytopenia. Viraemia was demonstrated between 3 and 15dpi and the infected calves seroconverted by 15dpi. Prominent kidney lesions were endothelial cell swelling, proliferation of mesangial cells and podocytes leading to glomerular space obliteration. Degeneration and desquamation of cells lining seminiferous tubules were observed in two infected calves. Consolidation of lungs with interstitial pneumonia, mild gastroenteritis and systemic spread were also evident. It was concluded that Indian BVDV isolate induced moderate clinical disease in calves and glomerulonephritis resulting from acute BVDV infection was observed for the first time.

Genetic analysis of indian bovine viral diarrhea virus 1 isolates in N(pro) and entire gene region coding structural proteins.

Three Indian Bovine viral diarrhea virus 1 (BVDV-1) isolates were analyzed at genetic level in N(pro) (viral autoprotease) and entire gene region coding structural proteins, namely capsid (C) protein, E(rns), and envelope proteins E1 and E2. All these isolates were found to be of b subtype based on the entire 504 nt region of N(pro) and 1119 nt region of E2. However, in comparison with other isolates of this subtype, they were allocated inside the BVDV-1 subtype b cluster to a separate clade with a longer distance. Of six cysteine residues in N(pro) only three were totally conserved in all three isolates. The isolates showed 94.9-99.3% and 92.2-99.0% identities for the entire C-E2 gene region at nucleotide and amino acid levels, respectively. The lowest identity values (88.5-91.7%) were observed for E2 amino acid sequences. The identity of the isolates with Osloss, a reference BVDV-1 subtype b strain, was in the range of 82.1-89.9% for nucleotide and 78.6-89.2% for amino acid sequences in the C-E2 region. The N(pro)/C and E(rns)/E1 cleavage sites were highly conserved. The C/E(rns) and E1/E2 cleavage sites were more conserved from the N-end of E(rns) and the C-end of El, respectively. These findings suggest that some unique mutations have occurred in the described Indian BVDV-1 isolates, though they all belong to the BVDV-1 subtype b.