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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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20224
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Subject: Veterinary Epidemiology and Preventive Medicine × Start date: 2022 × Type: Thesis ×
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Now showing 1 - 4 of 4
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    ThesisItemOpen Access
    Evaluation of immune response in broiler chicks immunized with a minimum cold chain dependent Newcastle disease virus formulation
    (College of Veterinary Science, Assam Agricultural University, Khanapara Campus, 2022-09) Ahmed, Rofique; Nath, Mrinal Kr
    Among the infectious diseases of poultry, Newcastle disease (ND) is considered one of the most economically fatal viral diseases causing morbidity and mortality of about 90-100% in its velogenic form. Only through vaccination the economic menace and clinical condition caused by NDV can be controlled. But commercially available vaccines against ND are generally thermolabile and lose their potency if kept at room temperature (25°C) for 1-2 hours. The recent COVID-19 pandemic clearly showed the weakness of the vaccine supply chain and its maintenance. The lack of thermostable formulations is one of the major limitations that the COVID-19 pandemic has brought to light. Addressing the need for thermostable vaccine development, the present study was carried out with the study of the thermal stability of a thermostable NDV vaccine formulation (As/Km/19/44) and its immunogenic potential in broiler chicks. In the present study, after receiving the thermoadapted ND seed virus (As/Km/19/44) confirmation was done by haemagglutination test (HA) and by Reverse Transcription- Polymerase Chain Reaction (RT-PCR) by the amplification of the 363 bp partial F gene. After confirmation, a thermal stability test of the seed virus (As/Km/19/44) was done by subjecting the isolate at 40°C and 56°C for 120 minutes respectively. The thermoadapted ND seed virus (As/Km/19/44) retained its HA activity and infectivity at 40°C up to 120 minutes without any decay in virus titre and at 56°C, the thermoadapted ND seed virus (As/Km/19/44) retained its half-life for 83.13 and 96.60 minutes in terms of HA activity and infectivity respectively. Further, lyophilization of the seed virus (As/Km/19/44) was done using chemical excipients viz., Pullulan (10% w/v), Trehalose (0.5M) and Inulin (45mg/ml) to prepare the immunogenic formulation. After formulation, the comparative HA activity and infectivity before and after lyophilization showed no significant difference at P<0.05. The lyophilized NDV immunogenic formulations (As/Km/19/44) were grouped and kept at different temperatures viz., 4ºC for six months, room temperature (about 25°C) for six months, 37ºC for one month, and 56ºC for 15 days for evaluating the thermal stability. At 4ºC, no fall of virus titer in terms of HA activity and infectivity were recorded for up to 6 months. The estimated half-life period of the live NDV immunogenic formulation exposed at room temperature (around 25°C), 37°C and 56°C in terms of HA activity and infectivity was found to be 1008 and 1037; 50.03 and 71.51; 2.194 and 2.764 days respectively. For evaluation of humoral immune response, the minimum cold-chain dependent NDV formulation (As/Km/19/44) was administered in experimental chicks through an intra-nasal route with a standard dose of 106EID50 per chick and compared with the commercial LaSota® vaccine. The HI (log2) and I-ELISA (log10) antibody titers in the serum samples of the experimental chicks at different days post-immunization revealed that there was no significant difference between overall humoral immune response in immunized chicks with minimum cold chain dependent live NDV immunogenic formulation As/Km/19/44 and commercially available LaSota® vaccine strain at P<0.001. Therefore, the minimum cold-chain-dependent NDV immunogenic formulation As/Km/19/44 can be recommended as a suitable live thermostable ND vaccine candidate for prevention and control of ND in areas where cold chain facilities are usually unreliable and can lead to the reduction of vaccine wastage, increase in vaccine efficacy, reduction in cost, ease of application and transportability.
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    ThesisItemOpen Access
    Transmission of Newcastle disease virus at domestic-wild bird interface
    (College of Veterinary Science, Assam Agricultural University, Khanapara Campus, 2022-09) Sharma, Abhilasha; Dutta, Jyoti B
    Wild birds have been known to be reservoirs of Newcastle disease virus and the disease has been identified as one of the endemic diseases in India despite vaccination. Moreover, wildlife-livestock interfaces have come into light as the most overlooked areas of disease emergence. In that context, to demonstrate and establish spillover and spillback of Newcastle disease virus in wild and domestic birds as well to identify epidemiological means facilitating transmission at interface areas, a study was undertaken to detect and characterize NDV in the pool maintained in wild and domestic birds along with some epidemiological studies. Samples were collected from a total of 321 birds, both wild (n=81) and domestic (n=240) and subjected to haemagglutination inhibition (HI) and RT-PCR. The apparent prevalence of NDV in wild birds was found to be 22.2% (95% CI: 13.2-31.3%) and 14.6% (95% CI: 10.1-19.1%) in domestic birds at the sampled areas in this study from April, 2021 to August, 2022 revealing that wild birds had a higher likelihood of being affected with NDV than that of domestic (OR=1.67, 95% CI: 0.89-3.16, P=.101). The highest proportion of NDV positive wild birds were from the interface areas of Kaziranga National Park (32.21%) and in domestic birds from the interface areas of Assam State Zoo (25%). The study revealed that NDV positive cases in were highest among the raptors in wild (56.3%) and granivores (7.78%) in case of domestic birds. 14.3% and 4% of the sampled swabs collected from wild (n=56) and domestic birds (n=151) respectively to be positive for NDV thereby illuminating the dominant shedding nature of the virus. Similarly, 23.9% and 12.6% of the sampled tissues collected from wild (n=67) and domestic birds (n=261) were found to be positive for the virus. Additionally, it was found that in wild birds, highest proportion of NDV detection was seen in winter (44.44%) whereas in domestic birds, it was seen highest in pre-monsoon season (31.42%). Furthermore, detection of NDV was found to be significantly correlated with species and colony of birds as well as with the type of samples collected. A total of 11 NDV isolates from wild (n=6) and domestic birds (n=5) were subjected to biological and molecular pathotyping on the basis of MDT and FPCS respectively. MDT for NDV isolates of wild birds ranged between 31.02±2.98 to 48.56 ±2.79 and 40.67±2.03 to 59.01±0.77 for NDV isolates of domestic rendering them to be of velogenic nature. Molecular pathotyping based on F protein cleavage site motif revealed the 11 isolates from both wild and domestic birds to be of the virulent nature with 112RRQKRF117 amino acid sequence at their F protein cleavage site. Representative NDV isolates from wild (n=6) and domestic (n=5) were sequenced and subjected to phylogenetic analysis which revealed all the wild isolates to be clustered under genotype VII in class II NDV, whereas isolates from wild birds were grouped under both genotype VII and XIII. A questionnaire survey was conducted to evaluate the risk factors enabling transmission of Newcastle disease virus at interface areas. Analysis of risk factors associated with NDV transmission showed that change in weather had 37 times significantly higher risk of mass mortality of Newcastle disease than that of no changes in weather, OR=37 95% CI :9.34- 146.65, P<.001. Similarly, farms in close proximity significantly had higher chances of ND affection, OR=3.96 95% CI :1.38-11.36, P=.008. The presence of waterbody nearby had a 5.11 times higher risk of being exposed to NDV than absence of waterbody nearby, OR=5.11 95% CI :1.78-14.67, P=.002. Other animals housed in the premises was also a significant risk factor, OR=3.87 95% CI :1.45-10.33, P=.006. Linear regression analysis revealed risk factors including mortality after weather change, presence of water body nearby, unavailability of clean drinking water, unavailability of chlorinated water, not practising all-in-all-out system; not practising down-time, interaction of other birds while feeding, mixing with neighbourhood ducks and geese, being housed with pigeons, deworming not carried out, no use of foot-baths, biosecurity not followed, being housed with pigeons, presence of bamboo groves in the farm, crows visiting the farm, predation by rodents, wild birds interacting while feeding and seasonal migration of wild birds observed nearby to be significant risk factors at flock level. Knowledge and attitudes were found to have positive correlations with practices adopted by bird owners. A statistically insignificant link was found between knowledge and attitudes, but a positive trend line was observed between the two. The derived data base regression explained about 36.82% of total variation in practice.
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    ThesisItemOpen Access
    Epidemiology of rabies in Assam
    (College of Veterinary Science, Assam Agricultural University, Khanapara Campus, 2022-09) Boro, Prasanta Kumar; Dutta, Jyoti B
    In an epidemiological study on rabies in 11 districts in Assam, 65 post-mortem brain samples belonging to nine species were collected by foramen magnum approach from clinically suspected domestic and wild animals and tested at the WOAH Reference Laboratory for Rabies, Hebbal, Bengaluru – 560 024, Karnataka. Simultaneously, a questionnaire survey on the community was undertaken to evaluate the epidemiological determinants on rabies transmission. Forty two (64.61 %) samples tested positive by LFA and DFA. Of the nine species, five species i.e. cattle 27 (41.53%), dog 9 (13.85%), goat 4 (6.15%), pig 1(1.53%) and pony 1(1.53%) were confirmed for rabies. Aggression in 41 (97.62%) cases was the most common signs exhibited by the affected animals before death with only one positive case (2.38%) showing paralytic signs. There was no dog bite history in 33 (78.57%) cases while 9 (21.43%) cases had. Most of the livestock were free ranging and grazed nearby protected areas where presences of wild carnivores were evident. Seasonal distribution revealed similar numbers of cases (45.24%) during rainy and flood season (July-September) and post-harvesting (December-February) winter season. Gender-wise, 20 (47.62%) positive cases of cattle and goats were either pregnant or recently calved. Prevalence of rabies was found to be highest (64.29%) in the animals more than 3 years of age, followed by the animals between 1 to 3 years (23.81%) and below one year of age (11.90%). In rural areas distribution of rabies was highest (52.31%), semi-urban (9.32%) and urban (3.08%). Distribution maps of rabies in different parts of Assam were generated based on the GPS locations of the positive cases and heat map revealed a high risk zone in the Golaghat district. The areas adjoining the tea gardens had higher rabies cases (23, 54.76%). The questionnaire survey revealed a very low level of community awareness regarding rabies and its transmission. Lack of proper information from the field staff, immediate collection of samples from field and transportation of samples to the laboratory maintaining cold chain were the major constraints found during the study.
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    ThesisItemOpen Access
    PREVALENCE OF BAT LYSSAVIRUS IN ASSAM
    (College of Veterinary Science, Assam Agricultural University, Khanapara, Guwahati, 2022-01) DAS, TINKU; Dutta, Jyoti B.
    Rabies is one of the oldest known tropical viral zoonotic diseases caused by Lyssavirus of the family Rhabdoviridae, affecting all warm-blooded mammals. Annually ~ 60,000 people succumb to rabies every year, out of which, India alone bears the burden of 36 per cent of the global cases. Even though most of these cases are canine-mediated, but there is no dearth of data regarding bats being one of the primary reservoirs of the virus. Several species of bat Lyssavirus have been documented and bat-transmitted rabies in humans has been regularly reported since the last century. In the present study, 34 bat samples belonging to nine species of bats were collected from eight districts of Assam, namely, Kamrup (M), Baksa, Chirang, Barpeta, Kokrajhar, Golaghat, North Lakhimpur and Dhemaji, and tested for the presence of bat Lyssavirus as per the OIE guidelines. The samples were subjected to Lateral Flow Assay (LFA), Direct Fluorescent Antibody Technique (DFA), One-step PCR. None of the samples were positive for lyssavirus indicating absence of an active lyssaviral infection in the bats during the study period.