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Assam Agricultural University, Jorhat

Assam Agricultural University is the first institution of its kind in the whole of North-Eastern Region of India. The main goal of this institution is to produce globally competitive human resources in farm sectorand to carry out research in both conventional and frontier areas for production optimization as well as to disseminate the generated technologies as public good for benefitting the food growers/produces and traders involved in the sector while emphasizing on sustainability, equity and overall food security at household level. Genesis of AAU - The embryo of the agricultural research in the state of Assam was formed as early as 1897 with the establishment of the Upper Shillong Experimental Farm (now in Meghalaya) just after about a decade of creation of the agricultural department in 1882. However, the seeds of agricultural research in today’s Assam were sown in the dawn of the twentieth century with the establishment of two Rice Experimental Stations, one at Karimganj in Barak valley in 1913 and the other at Titabor in Brahmaputra valley in 1923. Subsequent to these research stations, a number of research stations were established to conduct research on important crops, more specifically, jute, pulses, oilseeds etc. The Assam Agricultural University was established on April 1, 1969 under The Assam Agricultural University Act, 1968’ with the mandate of imparting farm education, conduct research in agriculture and allied sciences and to effectively disseminate technologies so generated. Before establishment of the University, there were altogether 17 research schemes/projects in the state under the Department of Agriculture. By July 1973, all the research projects and 10 experimental farms were transferred by the Government of Assam to the AAU which already inherited the College of Agriculture and its farm at Barbheta, Jorhat and College of Veterinary Sciences at Khanapara, Guwahati. Subsequently, College of Community Science at Jorhat (1969), College of Fisheries at Raha (1988), Biswanath College of Agriculture at Biswanath Chariali (1988) and Lakhimpur College of Veterinary Science at Joyhing, North Lakhimpur (1988) were established. Presently, the University has three more colleges under its jurisdiction, viz., Sarat Chandra Singha College of Agriculture, Chapar, College of Horticulture, Nalbari & College of Sericulture, Titabar. Similarly, few more regional research stations at Shillongani, Diphu, Gossaigaon, Lakhimpur; and commodity research stations at Kahikuchi, Buralikson, Tinsukia, Kharua, Burnihat and Mandira were added to generate location and crop specific agricultural production packages.

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Subject: Veterinary Microbiology × Author: NEHER, SAMSUN × End date: 2017 × Start date: 2013 × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    DEVELOPMENT OF USER FRIENDLY DIAGNOSTICS AND CELL CULTURE ADAPTED VACCINE CANDIDATE FOR DUCK PLAGUE
    (Assam Agricultural University, Khanapara, Guwahati, 2016-05) NEHER, SAMSUN; Das, S. K.
    Duck plague or duck viral enteritis is an acute and contagious viral disease of ducks, geese swan and other species of the order Anseriformes. The disease is responsible for significant economic losses in duck husbandry due to heavy mortality, condemnation and decrease in egg production in duck. Besides clinical and postmortem findings, laboratory diagnosis is essential to confirm the disease in cases of outbreaks. Conventional diagnostic methods are labour intensive, time consuming and less sensitive. There is an urgent need for development of rapid, sensitive and cost effective in house as well as user friendly diagnostic test so as to confirm the disease at clinical phase in the field itself. Again, vaccination is the only available option for prevention and control of the disease. The present study was undertaken to develop user friendly diagnostics and potent cell culture adapted vaccine to control duck plague virus (DPV) infection. During the study period a total of 29 outbreaks of duck plague were attended. Various clinical and post mortem samples were processed for detection of viral DNA by PCR and viral antigen by S-ELISA. Serum samples collected from different districts were tested for presence of antibody by I-ELISA and Dot-ELISA. Duck plague virus was isolated in duckling, duck egg and DEF primary cell culture from the field tissue sample. Sequence and phylogenetic analysis of local DPV isolate and a vaccine strain was done to see the circulating virus in Assam. A cell culture adapted vaccine was developed, and safety and potency test was conducted to see the efficacy of the vaccine. In sero-epidemiological study, among the 445 serum samples tested by I-ELISA 348 (78.20%) were found positive for DPV antibody, however in Dot-ELISA 149 (33.48%) were found to be positive. A total of 380 samples were collected from clinically affected (107) and dead ducks (273). S-ELISA showing positive results in 25 (23.36%) in clinical samples and 188 (68.86%) post mortem samples, however in PCR a total of 231 (84.61%) post mortem samples and 68 (63.55%) clinical samples showed positive for duck plague virus specific nucleic acid. The present study showed that PCR is the suitable and reliable test for detection of duck plague virus. Among different tissue samples collected from dead birds, liver and spleen were found to be most suitable. In cases of clinical samples ducks whole blood was found to be preferred sample than the cloacal swabs and tracheal swab. However, due to simplicity of collection, cloacal swab may be the choice of sample from large flock. Reviving of field isolate in primary host followed by isolation in duck embryo and duck embryo fibroblast (DEF) cell culture made 100% recovery of virus. However, the DEF cell culture was found to be more suitable than embryonated duck egg for isolation. Sequence and phylogenetic analysis of the local isolates and a vaccine strain showed a close relationship among the local isolates with the vaccine strain. Local isolates also showed a significantly high degree of sequence identity with other DPV isolates from China, Vietnam, Korea and Germany. A highly virulent local strain was selected as vaccine candidate and adapted in CEF primary cell culture, whereas standard vaccines strain was adapted in CEF primary cell culture as well as in vero cell line. In safety and potency test of the CEF cell culture adapted DPV vaccine strain, ducklings were vaccinated with 0.5 ml of 103, 104 and 105 TCID50/ml dose of vaccine virus. All doses of vaccine were found to be safe and optimum for eliciting protective immunity in the vaccinated ducklings, and conferred 100% protection of ducklings challenged with 1 ml of 100 DID50 of virulent DPV. Thereby, the minimum dose containing 1 ml of 103 TCID50/ml of vaccine virus can be considered as optimum vaccine dose for providing protection, which can be further used for protection of ducks from duck plague. The present study clearly showed that duck plague is endemic in Assam causing high mortality in ducklings as well as in growing and adult ducks. Diagnostic tests I-ELISA, S-ELISA and Dot-ELISA along with molecular technique PCR could be companion diagnostic tools for confirmation of DPV as well as assessment of virus antibody. Significantly development of cell culture adapted vaccine and conferring of 100% protection can be an achievement of the study.