Bluetongue (BT) is a vector-borne, infectious and non-contagious viral disease of domestic and wild ruminants. BT is caused by bluetongue virus (BTV) belongs to the genus Orbivirus under family Reoviridae. BTV is transmitted by haematophagus route through biting midges Culicoides. Currently, BT is a notifiable disease to the World Organization for Animal Health (OIE) due to great economic losses associated with high morbidity and enormous potential to spread across the international borders. BTV causes clinical disease in sheep and subclinical disease in cattle and goats. There are 28 serotypes of BTV, out of which 23 have been reported from India either by virus isolation or detection of serotype-specific antibodies. BT is endemic in India and several outbreaks of BT with various serotypes have been reported in almost all the states of India. The various assays such as competitive ELISA, virus isolation, PCR, agar gel immunodiffusion assay, direct and sandwich ELISA, serum neutralization assay, and immunohistochemistry are widely used for the diagnosis of BTV. BT control program in India includes vector control, effective vaccination along with serological and entomological surveillance. Currently, pentavalent inactivated vaccine containing BTV serotypes 1, 2, 10, 16 and 23 is used in India to control BT. This review summarises the epidemiology of BTV in India and works carried out in CADRAD, ICAR-IVRI, Bareilly, Uttar Pradesh.

We report patho-morphological and virological characterization of SARS-CoV-2 in naturally infected, free ranging Indian Leopard ( Panthera pardus fusca ). Whole genome sequence analysis confirmed infection of Delta variant of SARS-CoV-2, possibly spill over from humans, but the case was detected when infection level had dropped significantly in human population. This report underlines the need for intensive screening of wild animals for keeping track of the virus evolution and development of carrier status of SARS-CoV-2 among wildlife species.

A study was carried out to ascertain the oxidant and antioxidant profile in amniotic fluid (AF) of pregnant Muzaffarnagari ewes infected with bluetongue virus serotype-1. Twenty-seven pregnant ewes were divided into three groups as control and two treatment groups. BTV-1 was inoculated into two treatment groups during early and mid-gestation at 35 days and 60 days, respectively. Animals were sacrificed at periodical intervals. Amniotic fluid was collected after resection of uterus and evaluated for lipid peroxidation, superoxide dismutase (SOD) and total antioxidant capacity (TAC). Lipid peroxidation showed elevation in infected groups (1.234 and 1.240 |jmol/ml in early and mid-gestation infected group, respectively) as compared to control (1.107 jmol/ml), whereas SOD and TAC decreased in infected groups (SOD: 0.895 and 0.898 U/L; TAP: 0.445 and 0.451 mM/L in early and mid-gestation infected group, respectively) as compared to control (SOD: 1.280 U/L; TAP: 0.664 mM/L). Malondialdehyde (MDA) levels decreased gradually from early to mid-gestation stage and increased towards late gestation. Antioxidant enzyme SOD and TAC increased towards late gestation in control group. MDA levels also increased and SOD and TAC decreased towards last trimester in both infected groups. Among, thirty-two foetuses retrieved, two foetuses showed cerebellar malformation such as general cerebellar hypoplasia and Purkinje cell dysplasia towards the late gestation in infected groups. It was concluded that BTV-1 added oxidative stress to foetal growth in the womb and responsible for central nervous system malformation. Thus, amniotic fluid could be the valuable diagnostic sample to evaluate oxidative biomarkers in viral induced central nervous system malformations in foetuses.

Introduction: Bluetongue virus (BTV) is a species of genus Orbivirus belonging to the Sedoreoviridae family. Bluetongue (BT) is endemic in India and responsible for causing significant economic losses to livestock farmers. In India, antibodies to BTV serotype 24 (BTV-24) have been reported in 2005; it was first isolated in 2010, and it caused several outbreaks in sheep during 2012–2014. The in vivo studies investigating the pathogenetic potential of various BTV serotypes in the susceptible host sheep are scarce. Furthermore, detailed investigations to elucidate the pathogenetic mechanisms of BTV-24 under experimental conditions in sheep are not available. Because of its impact on the livestock economy, the present study was undertaken for the first time to explore the infection kinetics, pathology, pathogenesis, and immune responses against the Indian isolate of BTV-24 in sheep under experimental conditions. Methods: Six native sheep were infected intradermally with BTV-24 at 10 ⁶ TCID ₅₀ /mL concentration, and six sheep were inoculated with uninfected cell culture fluid. Animals were euthanized at 4, 7, 11, 16, 45, and 60 days post-inoculation (DPI). The sequential pathology, BTV localization by immunohistochemistry, BTV quantification by quantitative PCR (qPCR), immune cell kinetics [CD4 ⁺ and CD8 ⁺ T lymphocytes in peripheral blood mononuclear cells (PBMCs), prescapular lymph node (PSLN), and spleen] by fluorescence-activated cell sorting (FACS), and cytokine estimation by qRT-PCR were studied. Results: The BTV-24-infected animals showed pyrexia, conjunctival and oral mucosal congestion, cyanosis of tongue, serous to catarrhal nasal discharge, and viremia. Gross pathological lesions were observed in the lymph nodes, lungs, and kidneys, with the lymph nodes being enlarged, edematous, and hemorrhagic. Subintimal hemorrhage at the base of the pulmonary artery (pathognomonic lesion of BT) was observed at 7 DPI. Histopathological lesions were prominent in lymph nodes, spleen, heart, lungs, and cerebral endothelium. Severe hemosiderosis in spleen, and hemorrhages and hyalinization of tunica media in pulmonary artery at 7 DPI were observed. Development of clinical signs and gross and histopathological lesions in BTV-24-infected animals emphasized the moderate progression of disease and enhanced virulence of the serotype. Humoral immune response was significantly high at 5, 11, 16, 21, 45, and 60 DPI. Cell-mediated immune response-like kinetics of CD4 ⁺ and CD8 ⁺ T lymphocytes showed a sharp decline during the early stage and an increase of CD8 ⁺ T lymphocytes during later stages of infection. BTV antigen was detected consistently in tongue, thymus, trapezius muscle, heart, and pulmonary artery by immunohistochemistry and qPCR. Significant changes in the levels of cytokines [interferon-alpha (IFN-α), IFN-β, IFN-γ, interleukin-2 (IL-2), IL-12, and tumor necrosis factor-alpha (TNF-α)] and upregulated expression of apoptotic markers, B-cell lymphoma-2 (Bcl-2), and caspase-3 in the spleen and lymph nodes were correlated with peak viremia. Conclusion: The results of this study can be used to formulate effective preventive and control measures and to develop a suitable vaccine against BTV-24 to minimize economic losses.