Since 1998 there have been significant changes in the global distribution of bluetongue virus (BTV). Ten previously exotic BTV serotypes have been detected in Europe, causing severe disease outbreaks in naïve ruminant populations. Previously exotic BTV serotypes were also identified in the USA, Israel, Australia and India. BTV is transmitted by biting midges (Culicoides spp.) and changes in the distribution of vector species, climate change, increased international travel and trade are thought to have contributed to these events. Thirteen BTV serotypes have been isolated in India since first reports of the disease in the country during 1964. Efficient methods for preparation of viral dsRNA and cDNA synthesis, have facilitated full-genome sequencing of BTV strains from the region. These studies introduce a new approach for BTV characterization, based on full-genome sequencing and phylogenetic analyses, facilitating the identification of BTV serotype, topotype and reassortant strains. Phylogenetic analyses show that most of the equivalent genome-segments of Indian BTV strains are closely related, clustering within a major eastern BTV ‘topotype’. However, genome-segment 5 (Seg-5) encoding NS1, from multiple post 1982 Indian isolates, originated from a western BTV topotype. All ten genome-segments of BTV-2 isolates (IND2003/01, IND2003/02 and IND2003/03) are closely related (>99% identity) to a South African BTV-2 vaccine-strain (western topotype). Similarly BTV-10 isolates (IND2003/06; IND2005/04) show >99% identity in all genome segments, to the prototype BTV-10 (CA-8) strain from the USA. These data suggest repeated introductions of western BTV field and/or vaccine-strains into India, potentially linked to animal or vector-insect movements, or unauthorised use of ‘live’ South African or American BTV-vaccines in the country. The data presented will help improve nucleic acid based diagnostics for Indian serotypes/topotypes, as part of control strategies.
Transplacental transmission (TPT) of wild-type Indian BTV-1 had never been experimentally proved. This study was first time investigated TPT of Indian BTV-1 (isolated from aborted and stillborn goat fetal spleens). The sequential pathology, virological and immune cell kinetics (CD4 + , CD8 + T-lymphocytes and NK cells in spleen and PBMCs), and apoptosis in IFNAR1-blocked pregnant mice during early (infected on 1 GD) and mid (infected on 8 GD) gestation have been studied. There was higher rate of TPT during mid stage (71.43%) than early (57.14%) stage. In early stage reduced implantation sites, early embryonic deaths, abortions, and necro-haemorrhagic lesions had observed. Mid stage, congenital defects and neurological lesions in foetuses like haemorrhages, diffuse cerebral edema, necrotizing encephalitis and decreased bone size (Alizarin red staining) were noticed. BTV-1 antigen was first time demonstrable in cells of mesometrium, decidua of embryos, placenta, uterus, ovary, and brain of foetuses by immunohistochemistry and quantified by real-time qRT-PCR. BTV-inoculated mice were seroconverted by 7 and 5 dpi, and reached peak levels by 15 and 9 dpi in early and mid gestation, respectively. CD4 + and CD8 + cells were significantly decreased (increased ratio) on 7 dpi but subsequently increased on 15 dpi in early gestation. In mid gestation, increased CD8 + cells (decreased ratio) were observed. Apoptotic cells in PBMCs and tissues increased during peak viral load. This first time TPT of wild-type Indian BTV-1 deserves to be reported for implementation of control strategies. This model will be very suitable for further research into mechanisms of TPT, overwintering, and vaccination strategies.Bluetongue (BT) is a non-contagious, insect-borne (mainly biting midges of Culicoides spp.) disease of domestic (primarily sheep) and wild ruminants, caused by bluetongue virus (BTV). BTV is the prototype member of the genus Orbivirus in the family Reoviridae 1 . Most prominent clinical signs of BT are usually seen in sheep. Experiment-2.The mid stage pregnant mice were inoculated I/V with 50 μl of inoculum containing 1 × 10 6 TCID 50 /ml of BTV-1 at 8 GD and acted as infected group. The mice were injected with anti-mouse IFNAR1 monoclonal antibody at a dose rate of 2.5 mg/mouse, I/P at 24 hours before BTV-1 infection. The control mid pregnant mice received I/V 50 μl of uninfected tissue culture medium and 24 h before, anti-mouse IFNAR1 monoclonal antibody at a dose rate of 2.5 mg/mouse, I/P and acted as placebo. Three mice from BTV-1 inoculated and two mice from control pregnant groups were sequentially euthanized by cervical dislocation on 1 (9 GD), 2 (10 GD), 3 (11 GD), 5 (13 GD), 7 (15 GD), 9 (17 GD), and 12/13 (20/21) dpi. The dams and all foetuses were examined thoroughly during post-mortem and body weight of foetuses was recorded.inocula. The bluetongue virus serotype-1 used in this experiment was isolated from stillborn and aborted fetal spleens of goats in July 2007 at Sardarkrushinagar, Gujarat, India 20 . The BTV-1...
Four outbreaks of buffalopox in domestic buffaloes, with considerable mortality with high case fatality rates in young buffalo calves and high morbidity with significant productivity loss in terms of reduction in milk yield in adult animals along with severe zoonotic infection in milk attendants were recorded at various places in India, during 2006-2008. In buffaloes, the pox lesions were confined to udder and teats of the majority of the affected animals, and in few animals the lesions were appeared on the hindquarters, indicating generalized infection. The overall disease morbidity, mortality and case fatality rate were 6.8%, 0.7% and 11.4% respectively. Milkers developed pox-like lesions on the hands, forearms and forehead accompanied by fever, axillary lymphadenopathy and general malaise. The causative agent of the outbreaks, buffalopox virus (BPXV), was confirmed upon virus isolation in cell culture, electron microscopy, A-type inclusion (ATI) and ankyrin repeat protein (C18L) gene-specific polymerase chain reactions (PCR). Further, sequence analysis of the BPXV isolates from human and buffalo showed more identity of ATI and C18L genes sequences with that of other orthopoxviruses at nucleotide and amino acid levels and confirmed a close relationship of BPXV with Vaccinia virus (VACV) or VACV-like viruses. Considering the zoonotic impact and productivity losses of buffalopox infection, the control measures are imperative in curtailing economic and public health impact of the disease.
Bluetongue virus serotype-1 (BTV-1) was isolated from Culicoides oxystoma vectors captured on livestock farms in two places of Gujarat, India. The viruses were isolated on BHK-21 cells, which produced characteristic BTV-related cytopathic effects between 24 and 48 h post-infection. Virus antigen was demonstrated in infected cells at different passage by a BTV-specific sandwich ELISA. Further, polyacrylamide gel electrophoresis and silver staining of viral genomic RNA revealed ten double-stranded RNA segments characteristic of BTV. Serotype of the isolates was identified by virus neutralization and PCR coupled with sequencing. The isolates were designated as SKN-7 and SKN-8 and their genome segment-2 (VP2) were sequenced. Phylogenetic analyses revealed very close relationship between them although they are not identical. SKN-8 showed closer relationship with a recently isolated BTV-1 from goat. Bluetongue virus was earlier isolated from Culicoides in adjacent state more than 20 years ago, although the serotype of the virus was not determined.
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