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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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20171
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Subject: Veterinary Microbiology × Author: Roychoudhury, Parimal × End date: 2017 × Start date: 2013 × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    MOLECULAR AND ANTIGENIC CHARACTERIZATION OF CLASSICAL SWINE FEVER VIRUS ISOLATED FROM NORTH EASTERN REGION OF INDIA
    (Assam Agricultural University, Khanapara, Guwahati, 2017-07) Roychoudhury, Parimal; Sarma, Dilip Kumar
    The present study “Molecular and antigenic characterization of classical swine fever virus isolated from North Eastern region of India” was undertaken to explore the genogroups and subgroups of CSF virus isolated from different geographical location of North Eastern region of India, their genetic relatedness within and when compared to other isolates from different areas from the available data. Antigenic relatedness of the isolates to vaccine virus and to a local isolate(Lab. No.852) were studied by serological tests such as liquid phase blocking ELISA (LPB-ELISA) and neutralization peroxidase linked assay(NPLA).Antisera for the serological tests were raised against vaccine virus and a local isolate(Lab. No.852) in pigs and rabbits. Tissue samples collected during January 2011 to October 2012 were screened for Classical swine fever(CSF) virus antigen by sandwich ELISA(sELISA) and subsequently confirmed nested reverse transcriptase polymerase chain reaction (RT-nPCR). Out of 32 positive samples, virus could be isolated from 26 samples in PK-15 cell line. Seventeen isolates were selected for molecular characterization and 20 isolates for antigenic characterization. Virus Infectivity titres are expressed as log value of tissue culture infectious dose(logTCID50) per volume(0.1ml) of virus suspension, which varies in the range of 3.75 to 4.50 among the 20 isolates used for antigenic characterization. Cloning of three partial genomic region i.e.271nt fragment of 5′UTR, 271nt of E2 and 449nt of NS5B were carried out in pDrive vector and were subsequently sequenced by outsourcing. Phylogenetic analysis of the isolates using 150nt of UTR, 190nt of E2 and 409nt of NS5B revealed that 15 out of 17 isolates belonged to genogroup 1.1 and 2 isolates belong to genogroup 2.2. Nucleotide polymorphism at several locations were observed when compared to Alfort/187(GenBank Acc. No. X87939).Pair wise distance analysis of the E2 sequences of the 17 isolates showed 98.4% to 100% similarity within the same 1.1 genogroup While, two sequences of 2.2 genogroup showed 100% similarity with each other. Pair wise distance analysis of the 5′UTR sequences of the 17 isolates showed very close similarities, ranged between 99.3% to 100% While, two sequences of 2.2 genogroup showed 100% similarity with each other. Pair wise distance calculation of the NS5B sequence within the seventeen isolates from different parts of North Eastern India revealed overall similarity ranges from 85.1% to 100%. Homologous 2.2 group isolates showed 100% similarity with each other. Six representative isolates (ML-1, ML-2, ML-3, ML-4, AS-1 and AS-3) recovered during August and September 2011 within the genogroup 1.1 were compared among themselves as well as with available published sequences during 2005-2007. The results clearly indicate the close relation of the present isolates with the previously isolated virus from same North Eastern Region. However, the sequences are slightly diverge from each others, compared during 2005 to 2012 clearly indicates the endemic status of the region. Antigenic characterization of 20 isolates were carried out by comparing 50% inhibition log titre in LPB-ELISA and neutralization inhibition log titre in NPLA using hyperimmune serum against vaccine virus and a local isolate(Lab. No.852) raised in rabbit and pig.The 50% inhibition log titre of CSF virus isolates in LPB-ELISA obtained by using rabbit hyperimmune serum against the vaccine virus as well as against local isolate (Lab. No. 852) ranged from 1.505 to 2.107. The overall mean titre of CSF virus isolates in LPB-ELISA with the vaccine virus antiserum was 1.820±0.032 and with the local isolate (Lab. No.852) antiserum was 1.806±0.029 . The results of statistical analysis revealed no significant difference (’t’ value=0.373; P<0.05) between the mean of the 50% inhibition titre of CSF virus isolates with the vaccine and local isolate (Lab. No.852) antiserum in LPB-ELISA. The 50% inhibition log titre of the present isolates in LPB-ELISA obtained by using pig hyperimmune serum against the vaccine virus as well as against local isolate (Lab. No. 852) ranged from 1.505 to 2.107. The overall mean titre of CSF virus isolates in LPB-ELISA with the vaccine virus antiserum was 1.806±0.095 and with the local isolate antiserum was 1.818±0.025 . The results of statistical analysis revealed no significant difference (’t’ value=0.331; P<0.05) between the mean of the 50% inhibition titre of CSF virus isolates with the vaccine and local isolate antiserum in LPB-ELISA. Neutralization log titre of CSF virus isolates in NPLA using the rabbit hyperimmune serum raised against the vaccine virus as well as serum raised against a local isolate(Lab. No.852) ranged from 1.505 to 1.982. The overall mean titre of CSF virus in NPLA using rabbit hyperimmune serum, the vaccine virus antiserum was 1.754±0.028 and with the local isolate (Lab. No.852) antiserum was 1.789±0.026. The results of statistical analysis revealed no significant differences (‘t’ value,0.882; P<0.05) between the mean of the neutralization titre of CSF virus isolates with the vaccine virus and reference field virus antiserum in NPLA. The neutralization log titre of CSF virus isolates in NPLA using pig hyperimmune serum raised against the vaccine virus, ranged from 1.505 to 1.982 and against the local isolate(Lab. No.852), ranged from 1.505 to 1.806. The overall mean titre of CSF virus in NPLA using pig hyperimmune serum, the vaccine virus antiserum was 1.758±0.03 and with the local isolate (Lab. No.852) antiserum was 1.746±0.021 . The results of statistical analysis revealed no significant differences (‘t’ value,0.319; P<0.05) between the mean of the neutralization titre of CSF virus isolates with the vaccine virus and local isolate(Lab. No.852) antiserum in NPLA. Comparison of neutralization pattern of the isolates compared to vaccine virus antiserum and local isolate(Lab. No.852) antiserum by LPB-ELISA and NPLA using rabbit and pig hyperimmune serum revealed that the 50% inhibition mean log titre obtained in LPB-ELISA was slightly higher than the mean neutralization log titre obtained in NPLA in all the cases, but the mean titre obtained in the tests did not differ significantly. Antigenic characterization of six selected isolates (MZ-1,AS-1,MN-1,TR-1,AR-1,ML-1) representing genogroup 1.1 and 2.2 were selected for LPBE and NPLA using monoclonal antibody specific for CSF virus E2 glycoprotein. In LPBE, 50% inhibition log titre of the five isolates (MZ-1,AS-1,MN-1,AR-1 and ML-1) along with the vaccine virus and field isolate was 0.903.The neutralization log titre of CSF virus isolates in NPLA using monoclonal antibody showed similar log titre of 0.779 in four isolates(MZ-1,AS-1,AR-1,ML-1) along with the vaccine virus and field isolate, while two isolates (MN-1 and TR-1) showed a titre of 0.602.The overall mean titre of six CSF virus isolates with the reference vaccine and field virus isolate using monoclonal antibody in LPB-ELISA was 0.865±0.037 and in NPLA was 0.734±0.028. Statistically, there was no significant difference (‘t’ value=0.015; P<0.05) between the mean of the 50% inhibition log titre and neutralization log titre of CSF virus isolates in LPB-ELISA and NPLA using monoclonal antibody. Comparison of 50% inhibition log titre and neutralization log titre of the isolates among the two geno groups and their subgroup 1.1 and 2.2 by LPB-ELISA and NPLA revealed no significant differences in the neutralization pattern using antisera against vaccine virus and a local isolate (Lab. No.852).