doi:10.5455/vetworld.2013.416-418 Prevalence of antibodies to bluetongue virus in large ruminants of Marathwada region of Maharashtra state

Aim: Seroprevalence study of BT antibodies in large ruminants of Marathwada region of Maharashtra state. Materials and Methods: A total of 246 serum samples of Cattle and Buffalo were screened for qualitative analysis of the BTV antibodies using a commercial competitive ELISA (cELISA) kit. Results: The results showed an overall percentage of BTV positive cattle and buffalo serum samples were 89.80% and 80% respectively. The results based upon the serum samples showing optical density values more than 50 per cent of the mean of negative control were taken as positive for presence of BTV antibodies. A high percentage of cattle showed BTV antibodies in places Parbhani (92.53%), Nanded (86%) and Aurangabad (81.81%). The percentage of BTV antibodies in buffaloes was 70%, 100%, 100% and 87.5% respectively in Parbhani, Nanded, Aurangabad and Hingoli. Conclusion: BTV antibodies were widely prevalent in cattle & buffaloes of Marathwada region and cELISA were found to be sensitive and effective for screening of BTV group specific antibodies.


Introduction
the state of Maharashtra [9].Since then, the disease has been recorded in 11 states in India, either on the basis of Bluetongue (BT) is a primarily midge-borne virus isolation or by the detection of group-specific hemorrhagic viral disease mainly in sheep and antibodies against the virus [10].occasionally in cattle and some species of deer [1].The Bluetongue virus (BTV) is the causative agent of global distribution of bluetongue virus (BTV) has bluetongue disease in cattle, an insect transmitted historically been between latitudes of approximately disease of ruminants [11].BTV belongs to Orbivirus 40°N and 35°S; however, the virus recently has spread genus of family Reoviridae.It has double stranded far beyond the upper limit of this traditional range in segmented RNA genome having ten discrete segments.northern Europe [2].The distribution of BTV coincides The seven of these segments encode structural protein with the distribution of competent culicoides insect (VP1 to VP7) and the remaining three encode for non vectors and appropriate climatic conditions [3].
structural proteins (NS1, NS2, NS3 and NS3A), NS3 However, specific vectors exist with specific and NS3A are encoded by tenth segment [12].The constellations of BTV serotypes and topotypes in virus is transmitted within its vertebrate hosts via bites relatively distinct global ecosystems [4].
of culicoides species.BTV infection of cattle is There are 24 distinct BTV serotypes and recently typically sub clinical and manifested by fever, sever Toggenburg orbivirus (TOV) is proposed to be a 25th salivation, oral ulceration, excoriation, pityriasis, burnt serotype [5] and, complete genome characterization muzzle, coronitis and lameness due to laminitis [13]. of a 26th BTV serotype from Kuwait [6].It is a Abortions, Infertility and foetal Anomalies have also notifiable disease of the World Organization for been attributed to BTV infection [13].It is also Animal Health (Office of international epizooties: characterized by prolonged viremia [14] during which OIE) due to its economic impact [7].In cattle, goats and the virus invariably is cell-associated [15].most wild ruminant species BTV is typically The virus remains in large ruminants for a limited asymptomatic or subclinical, although specific strains period (40-45 days) however; frequency of presence of of BTV, like the strain of serotype 8 currently BTV group specific antibodies in large ruminants is circulating in Europe, can cause severe disease in cattle very high.The seroprevalence studies in cattle and and goats [8].BT was first reported in India in 1961 in buffaloes in the particular BTV ecosystem have given valuable information about its epidemiology.In cattle the seroprevalence of BTV varies from 6 to 79 percent.and 69.19 and 58.33 percent by c-ELISA, respectively [22].In the state of West Bengal, the seroprevalence of The samples were considered to be positive for BTV in a sample population of 50 cattle, by indirect BTV antibody if the PI value is > 50 percent.The ELISA, revealed 52% of seroprevalence [23].In samples with PIs less than 50 percent were considered buffaloes a total of 173 sera sample tested by BTnegative.
AGID, CCIE and c-ELISA, for the presence of BTV

Results
antibodies and the seroprevalence observed was 35.26, 39.88 and 60.12 percent respectively [24].The sero-A serological survey involving 246 serum prevalence of 17 percent and 9 percent was reported by samples of cattle (206) and buffaloes (40) from various using agar gel precipitation test in cattle and buffaloes, places was carried out employing cELISA for respectively [25].The AGID were used and qualitative analysis of the BT antibodies (Table - Similarly by using cELISA seroprevalence study was cent of the mean of negative control were taken as conducted and recorded seropositivity of 30.76 percent positive for presence of BT antibodies.
among cattle, 37.14 percent in buffaloes, 40.36 percent A critical observation of ( [18,19]ionpresent the results of seroprevalence study of BT Bluetongue virus infection has been reported in antibodies using cELISA in large ruminants of bovine from several countries on the basis of presence Marathwada region of Maharashtra state.ofBTVspecificantibodiesandisolation of virus.InMaterials and Methodsareas where BT is endemic, the disease in cattle and Collection of Serum samples: About 5-7 ml of blood buffalo is not clinically overt.In these areas from cattle and buffalo was collected in 10 ml sterile seroconversion and viremia are the only evidences of test tubes from various slaughter houses (Three) that infection.Although BTV infection of ruminants is receive the animals from adjoining districts and one often subclinical or in apparent, infection also can organized farm of the Marathwada region in aseptic lead to severe disease with mortality in susceptible condition.Serum was separated and stored at -200C in animals[18,19].In different districts of Saudi Arabia small aliquots till use.seroprevalence of BTV antibodies observed, in that 49.3% of cattle, in Jizan and 53.4% of cattle in Eastern However, only 1 to 10 percent of these seropositive cattle developed clinical disease [16].The competitive average OD test sample) x 100.] Table-1) indicates that a among sheep and 64.86 percent among goats [27].high percentage of cattle showed BT antibodies in However, in present study 100 percent seroprevalence various districts of Marathwada region as 92.53 in buffaloes at Nanded and Aurangabad may be due to percent in Parbhani, 86 percent in Nanded and 81.81 small sample size and need further studies.The overall percent in Aurangabad.Similarly a high percentage of

Table - 1
. Prevalence of BT Antibodies in Cattle & Buffaloes as Determined by cELISA Staubach, C., Hendrickx, G. and Van der Spek, A. (2008) percentage of BT positive animals was given 47.01 Field observations during the bluetongue serotype 8 percent.epidemic in 2006.II.Morbidity and mortality rates, case fatality and clinical recovery in sheep and cattle in the Conclusion Netherlands.Prev.Vet Med , 87:31-40.The cELISA being a highly sensitive, specific and 9. Sapre, S.N. (1964) An outbreak of 'bluetongue' in goats and sheep in Maharashtra state, India.Vet.Rev. (M&B), 15: 69rapid test was found to be advantageous in present 71.study.High percentages of BT antibodies in cattle and