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Anand Agricultural University, Anand
Anand Agricultural University (AAU) was established in 2004 at Anand with the support of the Government of Gujarat, Act No.(Guj 5 of 2004) dated April 29, 2004. Caved out of the erstwhile Gujarat Agricultural University (GAU), the dream institution of Sardar Vallabhbhai Patel and Dr. K. M. Munshi, the AAU was set up to provide support to the farming community in three facets namely education, research and extension activities in Agriculture, Horticulture Engineering, product Processing and Home Science. At present there seven Colleges, seventeen Research Centers and six Extension Education Institute working in nine districts of Gujarat namely Ahmedabad, Anand, Dahod, Kheda, Panchmahal, Vadodara, Mahisagar, Botad and Chhotaudepur
AAU's activities have expanded to span newer commodity sectors such as soil health card, bio-diesel, medicinal plants apart from the mandatory ones like rice, maize, tobacco, vegetable crops, fruit crops, forage crops, animal breeding, nutrition and dairy products etc. the core of AAU's operating philosophy however, continues to create the partnership between the rural people and committed academic as the basic for sustainable rural development. In pursuing its various programmes AAU's overall mission is to promote sustainable growth and economic independence in rural society. AAU aims to do this through education, research and extension education. Thus, AAU works towards the empowerment of the farmers.
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ThesisItem Open Access CHARACTERIZATION OF DETERMINANT FOR TRANSFERABLE ANTIMICROBIAL DRUG RESISTANCE AND VIRULENCE ASSOCIATED FACTORS OF S. GALLINARUM(AAU, Anand, 1999) Patel, Ashvinkumar Ramabhai; Roy, A.In the present study characterization of antimicrobial drug resistance and its transferable nature in S. gallinarum isolates was carried out. Further curing of R-determinants and the effect of curing on virulence on virulence associated factros viz., colicinogeny and serum resistance was ascertained. Virulence of isolates were assayed by lethality and invasiveness assay and attempts were also made to isolate plasmid from S. gallinarum isolates. In vitro antimicrobial drug resistance against 10 commonly used antibiotics were detected. All the S. gallinarum isolates showed resistance against one or more drug tested. All the isolates were resistant to sulfamethoxazole while higher number of isolates showed resistance to nalidixic acid, gentamicin and enrofloxacin. Moderate number of isolates showed resistance against furazolidone, streptomycin, tetracycline and cotrimoxazole while resistance against pefloxacin was shown by lesser number of isolates. Least resistance isolates were observed for chloramphenicol. In vitro transfer of drug resistance was also studied. Out of 12 S. gallinarum isolates tested all (100 per cent) were found to transfer resistance against tetracycline, nine (75 per cent) isolates transferred en bloc resistance against tetracycline, gentamicin and sulfamethoxazole while three (25 per cent) isolates transferred resistance against only tetracyc1ine. In vivo transfer of drug resistance was carried out from two donor strains of S. gallinarum to recipient E. coli strain. Out of two S. gallinarum strains tested both revealed transfer of drug resistance from donor to recipient. Total 20 (57.1 per cent) isolates out of 35 isolates tested were found to produce bacteriocin. Twelve isolates were tested for transfer of colicinogeny, out of which six (56 per cent) were able to transfer of colicinogeny to recipient E. coli strain along with multiple drug resistance. Elimination of drug resistance (curing) markers in six strains of S. gallinarum were studied using different chemical and physical method. The chemical agents used for curing were ethidium bromide (EtBr) and novobiocin (Novo) ethidium bromide and novobiocin combination and sodium dodecyl sulfate (SDS). In present study the elimination of drug resistance by chemical agents observed frequently. Use of EtBr and SDS resulted in curing of drug resistance in all six strains while five and four strains were cured by EtBr and Novo combination and novobiocin alone respectively. In physical method of curing, 3 out of six S. gallinarum strains were eliminated drug resistance on 1 day of incubation at 45°C and higher number of curing frequencies, was observed on subsequent days. Thus resistance markers were more readily eliminated by incubation at 45°C for prolonged periods of time rather than by chemical agents. Resistance of six strains of S. gallinarum wild and their cured derivatives to bactericidal effect of chicken serum was studied. The study revealed that all the wild and cured strains tested were resistant to chicken serum. To know the role of virulence associated factors like colicinogeny and serum resistance, virulence assay of six selected wild and their cured derivatives was carried out by determining their lethality as well as invasiveness ability in day old chicks. In lethality assay wild strains (S-21, S-4 and S-27) caused mortality 66.66, 60.00 and 46.66 per cent respectively, while their cured derivatives caused mortality of 46.66, 20.00 and 20.00 per cent respectively. At the 15th day post infection (PI) surviving birds revealed infection as per the CFU count method. In invasiveness assay there was no significant difference in the CFU count among S. gallinarum wild. isolates and their cured derivatives was observed upto 12 day CFU count, but by the 16th day none of the chicks survived in wild strains. Thus it indicates that wild strains were more invasive and lethal as compared to their cured derivatives. All the surviving birds in cured group revealed infection at 16th PI. There was no apparent difference found between lesions of wild and the cured derivatives during virulence assay. Isolation of plasmids from 10 wild and their eight cured derivatives of S. gallinarum were carried out. Majority of the strains showed a plasmid of molecular weight 56 Md. In addition other small plasmids found were of 2.8 Md and 1.79 Md molecular weight.ThesisItem Open Access SEROPREVALENCE AND DIAGNOSIS OF BLUETONGUE VIRUS BY REVERSE TRANSCRIPTASE POLYMERASE CHAIN REACTION(AAU, Anand, 1998) Hinsu, T. V.; Kher, H. N.Bluetongue (BT) is an insect transmitted viral disease of several species of domestic and wild ruminants. The disease is a cause for serious concern to livestock industry due to staggering direct and indirect economic losses. In many countries like India having considerable sheep population, the disease has become endemic. Severity of the infection depends upon the species and breed of animals, serotypes/strains of the virus and prevalent ecosystem. The present study was aimed to find out prevalence of Bluetongue virus (BTV) antibodies in domestic ruminants and of Epizootic haemorrhagic disease virus (EHDV) antibodies in cattle of Kutch district of Gujarat state. Agar gel immunodiffusion (AGIO) and competitive enzyme-linked immunosorbent assay (c-ELISA) employed for antibody detection were also compared in terms of their sensitivity and specificity. An attempt was also made to standardize Reverse transcriptase-polymerase chain reaction (RT-PCR) for detecting BTV nucleic acid. Out of 162 sera tested, 87 (53.70%) and 126 (77.78%) were found to be positive for BTV antibodies by AGID and c-ELISA respectively. Specieswise, 24.56 and 63.16% of sheep, 80.00 and 96.36% of goats and 58.00 and 74.00% of cattle revealed antibodies to BTV by AGIO and c-ELISA respectively. The highest prevalence rate was found in Northern-east region (70.69 and 86.21%), followed by Central (48.72 and 75.64%) and Southern-west region (30.77 and 65.38%) of the Kutch district, respectively by AGID and c-ELISA. Female animals (63.03 and 86.81%) showed more prevalence than male animals (36.63 and 66.20%), as determined by AGID and c-ELISA respectively. In sheep, higher prevalence rate in native Patanwadi breed (47.06 and 86.16%) was observed than the crossbreds (11.76 and 43.48%) by AGID and c-ELISA respectively. A total of 50 cattle sera tested for BTV antibodies were also tested for EHDV antibodies by EHDV-AGID test. Of these, 9 (18.00%) were found positive for EHDV antibodies. Amongst these positive sera, five reacted specifically to EHDV antigen, without crossreacting to BTV antigen. Comparison of c-ELISA and AGID tests for the detection of BTV antibodies, revealed that the former test was better in terms of sensitivity and specificity. Of the total 162 serum samples, 87 and 126 samples reacted positively in AGIO and c-ELISA respectively. Eighty six samples were found positive and 35 negative by both the tests; while 40 samples detected positive by c-ELISA were negative by AGIO. Only one sample reacted positively to AGIO but negative in c-ELISA. This sample turned out to be positive for EHDV antibodies. Relative sensitivity and specificity of AGIO to c-ELISA were 68.25 and 97.22% respectively and overall agreement between both the tests was 74.69%. RT-PCR was employed for detecting BTV nucleic acid using BTV groupspecific segment 7 prime and BHK-21 cells adopted BTV serotype 1. This was attempted essentially to standardize this highly sensitive technique, so as to use it routinely in future for the field samples. The study revealed an amplified product of 500 bp specific to the primer used in the study.ThesisItem Open Access SEROEPIDEMIOLOGY, ISOLATION AND PATHOGENICITY OF BLUETONGUE VIRUS(AAU, Anand, 1996) Chandel, Bharat Singh; Kher, H. N.Bluetongue (BT) is an infectious, non contagious disease of domestic and wild ruminants. Bluetongue virus ( BTV ) causes severe disease in sheep, which i s transmitted by insect vectors (Culicoides spp.) . The ability of BTVs to inflict pathological changes in susceptible sheep depends on the virulence of a particular viral isolate , susceptibility of the host and a number of environmental factors related to climatic conditions. The present study was aimed at the seroepidemiology, prevalence of BTV serotypes in sheep, isolation, propagation and identification of local isolates and pathogenicity of BTV in natural and experimental cases of sheep. This study also covered the seroprevalence of epizootic haemorrhagic disease virus (EHDV) in cattle and buffaloes as it is related to orbivirus group. A seroepidentiological survey of BTV precipitating antibodies was carried out by agar gel immunodiffusicm ( AGID ) test in different species of livestock in Gujarat. Out of 1623 sera tested, 407 (25.07%) were found to be positive for BTV antibodies.ThesisItem Open Access ANTIGENIC CHARACTERIZATION OF EGG DROP SYNDROME-1976 (EDS-76) VIRUS(AAU, Anand, 1994) Bhalja, S. R.; Anjaria, J. M.Egg drop syndrome-1976 (EDS-76) virus has gained importance as one of the major causes of drop in egg production. EDS-78 virus has representative strains like 127 and BC14 which are identical serologically. The possibility of appearance of new isolates can not be ruled out by investigating the variations in immunogenic fractions and their interrelationship say provide indications to select a particular strain for vaccine production and to correlate specific antigenic fractions to immunogenicity of the virus isolate. The present work was on establishing antigenic relationship between strain 127 and two local isolates Sb and Kr of BDS-76 virus employing Haemagglutination inhibition (HI), Agar gel inmunodiffusion (AGID), Counter immunoelectrophoresis (CIEP) and Cross immunoeleotrophoresis (CrIEP). No much significant variation could be observed in the HI titres of sera against strain 127 and isolates Sb and Kr. Thus isolates of EDS-76 were indistinguishable based on HI test. Two common sharing lines were observed in strain 127 and Kr isolate, while one common sharing line was observed in Sb isolate with homologous as well as heterologous system in AGID. More number of precipitation lines were detected in ClEP than that in AGID in homologous and heterologous systens. Closed antigenic relationship was observed among strain 127 and isolates Sb and Kr. In standardized CrIEP using homologous and heterologous system of strain 127 and isolates Sb and Kr, four immuno precipitates were observed in each case. No apparent differences could be established among three isolates (strain 127 and isolates Sb and Kr of EDS-76 virus) by HI test, AGID, CIEP and CrIEP.ThesisItem Open Access SEROPREVALENCE, ANTIGEN DETECTION, EXPERIMENTAL INDUCTION AND ELECTRONMICROSCOPY OF CANINE PARVOVIRUS(AAU, Anand, 1994) Shukla, Devendrakumar V.; KHER, H. N.In veterinary field, dog practice has gained an important position, particularly due to the constant association of man with dog. Canine parvovirus (CPV) infection has emerged as a new disease entity clinically characterized by servere vomition and diarrhoea. The present study on CPV was aimed at screening dog population in and around Anand and Baroda region for prevalence of antibodies against CPV, detection of viral antigen in clinical cases, pathological study in experimental pups, an attempt for isolation and propagation of virus in cell-culture and demonstration of CPV under electronmicroscope (EM).ThesisItem Open Access SEROPREVALENCE, EXPERIMENTAL INDUCTION AND DETECTION OF EGG DROP SYNDROME 1976 VIRUS(AAU, Anand, 1993) Rangnekar, Alpana G.; Kher, H. N.During the last decade, Egg Drop Syndrome has gained importance as one of the major causes of drop in egg production. The present study was aimed at screening of poultry population in and around Anand for the prevalence of antibodies against Egg Drop Syndrome-1976 (EDS-76) virus, detection of virus from clinical cases and its effect on the laying hens and on chicken embryos. Out of the 310 samples screened, 212 samples (68.38 per cent) were found to contain the antibodies against EDS-76 virus by haeraagglutination-inhibition (HI) test. Only one farm was found to be sero-negative, though it had a complaint of drop in egg production. Of the 10 pooled faecal samples collected from the farms, 2 samples were found positive for EDS virus as ascertained by haemagglutination (HA) and haemagglutination-inhibition (HI) tests. Maximum seroprevalence (81.25 per cent) was recorded in the age group of 46-55 weeks, followed by the age group of 36-45 weeks (78 per cent). Forty per cent seroprevalence was detected in the age group of 25-35 weeks. It was possible to produce experimental infection in the 36 week old layers by the EDS virus 127 and the two field isolates (designated as Sb and Kr). Drop in egg production and egg abnormalities were evident. The antibody levels in the serum and egg yolk for each group were high at 21 days PI though the egg yolk antibody levels were slightly lagging behind the serum antibody levels by this time. The histopathological changes were most characteristic and restricted to the pouch shell gland areas of the uterus. In the chicken embryos, severe congestion with mild to moderate haemorrhages in the liver, kidneys and spleen were observed. HA activity was shown by the harvested allantoic fluids.ThesisItem Open Access ASSESSMENT OF IMMUNE RESPONSE TO HAEMORRHAGIC SEPTICAEMIA ALUM PRECIPITATED VACCINE IN CALVES(AAU, Anand, 1993) Lakhtaria, P. T.; Kher, H. N.Studies on immune response to haemorrhagic septicaemia alum precipitated vaccine in cow calves was undertaken at the Department of Veterinary Microbiology, College of Veterinary Science and Animal Husbandry, Anand. Twenty four unvaccinated healthy cow calves of either sex between the age group of four and eight months of Livestock Research Station and Animal Nutrition Department, Veterinary College, Anand were randomly divided into four groups viz., groups I, II, III and IV, each group having six calves. The calves of groups I, II and III were vaccinated with 5 ml of haemorrhagic septicaemia alum precipitated vaccine subcutaneously once, twice and thrice, respectively. Interval between two vaccinations for groups II and III was seven days. The calves of group IV were vaccinated with 5 ml of HS alum precipitated vaccine with simultaneous treatment of levamisole hydrochloride at dose rate of 2.5 mg per kg body weight intramuscularly. The calves of each group were bled prior to the first vaccination and thereafter at monthly interval upto six months. The sera were subjected to IHA test, CFT and PMPT for assessment of immune response. In the sera of calves of group I, overall duration of immunity toy single vaccination was observed upto six months, with variations in peak levels as ascertained by different tests employed. Maximum level of mean IHA antibody titres was at months three and five with no significant difference from that at other months including pr«-vaccination stage. Maximum level of mean CP antibody titres was at month four with no significant difference from that at months two, three, five and six, but it differed significantly from that at month one and pre-vaccination stage. Maximum survivability of mice was observed at months one, two and four. No significant difference in IHA antibody titres was observed in sera of calves of groups II and III in comparison to group I Group mean CF antibody titres of groups I and II did not differ significantly, but the group mean CF antibody titres of group III were significantly higher than those of groups I and II. No significant difference between the survivability rate of mice of groups I, II and III was observed in PMPT. These results indicated that twice vaccination failed to increase immune response, but thrice vaccination had increased the CF antibody titre with no effect on IHA antibody and mouse protecting antibodies. In the sera of calves of group IV, levamisole treatment increased mean CF antibody titres significantly, but failed to increase IHA antibody titres and passive mouse protecting antibody in comparison to calves of group I. While comparing efficacy of different tests, it was observed that IHA titres increased significantly at month two and reached to its peak during months three to five except for drop at month four and fell back at month six close to the level of month two titre. These mean differences were statistically highly significant. No definite conclusion could be made regarding IHA titre. The mean CF titre value increased significantly at month one in relation to pre-vaccination titre. The peak level of mean CF antibody titres were'observed at months two, three and four followed by significant decline at month five and further significant decline at month six. The mean CF values observed during different intervals of post-vaccination period were significantly higher than that at pre-vaccination stage. The results of PMPT indicated that mean value for survivability rate in mice at different months of post-vaccination period were significantly higher than that at pre-vaccination stage. The values were found highest at months one and two followed by gradual decrease during months three, four, five and six.ThesisItem Open Access ISOLATION OF INFECTIOUS BURSAL DISEASE VIRUS (IBDV), ITS COMPARISON WITH VACCINE STRAINS AND EFFICACY OF DIFFERENT VACCINATION REGIMENS IN PASSIVELY IMMUNE CHICKS(AAU, Anand, 1995) Hirpurkar, Sadananda D.; Kher, H. N.Infectious bursal disease (IBD) which was characterised by relatively less mortality but more immunosuppression was earlier prevalent in India. During a past couple of years, there is country-wide change in pattern of disease with high mortality rates. Some of the farms investigated in the present study have also experienced high mortality among both, layers (six to 14 weeks) and broilers (four to six weeks). Present study was undertaken on isolation of IBDV from field samples, study their pathogenicity and antigenicity in comparison with existing vaccine strains; and formulation of vaccination regimen effective enough to give protection to chicks in presence of maternal antibody. Before taking up virus isolation, tissue homogenates from clinical cases were examined by agar gel diffusion test (AGDT) against reference antiserum and their identity as IBDV was confirmed. Overall AGDT positive samples ranged between 40.0 and 70.5 per cent. Positive field samples were grouped under five groups (UNO, KAM, AND, HAL and NAV), according to different geographical regions. An attempt was made for isolation of IBDV from all the five representative samples in different indicator systems. Among experimentally inoculated chicks, the clinical disease was reproduced in case of UND, KAM and AND isolate infected group. No clinical symptoms were observed in NAL and NAV isolates infected groups. The birds inoculated with each samples and sacrified 48 hours PI, had gross and histopathologic changes suggestive of IBD. Specific precipitation lines were demonstrated in bursal homogenates. Out of five field isolates, three isolates (UND, KAM and AND) were adapted to growth in chick embryos by chorioallantoic membrane (CAM) route. Predominant changes were observed in the embryos which included slow and stunted growth, cutaneous edema and hemorrhages in subcutis. UND isolate was serially passed onto chicken embryo fibroblast (CEF) cell culture for its adaptation to growth. Characteristic cytopathic effect (CPE) was observed earliest, at 30 hours PI, and maximum CPE showing degeneration of about 80 per cent cell monolayer, at 48 hours PI. Syncytia formation due to aggregation of large number of nuclei of dead cells was observed in later stages. Other field samples failed to induce CPE in cell culture upto five serial passages. Comparative pathogenicity studies on five field isolates, one reference isolate (BAN) and vaccine strain of intermediate (Vac-I) and mild (Vac-M) virulence each, were carried in chicks, chick enbryos and CEF cell culture. Birds infected with UHD and BAM isolates showed severe clinical synptons and also hemorrhagic lesions in the bursa of Fabricius (BF), skeletal muscles and proventriculus-gizzard junction. Concurrent histopathologic lesions in the BF, at 48 hours PI, includes marked edema, hyperemia, necrosis of lymphoid cells, and formation of vacuoles or cystic follicles. In case of birds inoculated with Vac-I strain, the enlargement and edema was more marked which persisted longer. Vaccine strain induced histopathological lesions in BF which were of mild degree and comparable to those found in birds infected with NAL and NAV isolates. As regard to the pathogenicity of field isolates in chick embryos inoculated by CAM route, UND and BAN isolates caused almost 80 per cent mortality. Among other isolates, AND and KAM showed relatively low mortality rates followed by HAL and NAV. Unlike any of the recent field isolates tested in the present study, the UND isolate grew well in CEF cells exhibiting CPE in infected monolayers. Thus, only the UND and BAN isolates, were able to maintain consistent pathogenic potential in every laboratory system tested. Slight variation as regard to period required for initiation of CPE was observed in UND and BAN isolates when compared with that of vaccine strains. Highest virus infectivity titre was recorded in Vac-I strain, while in Vac-M strain the titre was lowest. The virus titres in both field isolates (UND and BAN) were sane. Neutralization and cross neutralization tests were carried out to assess the antigenic relatedness of a field isolate, reference isolate and vaccine strains using homologus and heterologus innune sera. The results indicated close antigenic relationship of the isolates with vaccine strains. In the present study, efficacy of three vaccination regiuens was evaluated in the progeny obtained from breeder hens having high levels of maternal antibody (MA). The levels of precipitating antibodies of progeny chicks at hatch indicated, on an average, 50 to 55 per cent passive transfer of MA to progeny. After hatch, higher levels of MA sustained for one week and afterwards declined steadily at the half-life of approximately six to eight days. MA attained low levels between 21 and 28 days of age. While after 28 days of age, precipitating antibodies were undetected by quantitative AGDT (QAGDT), still these antibodies were detected by enzyme linked immunosorbent assay (ELISA). Live vaccine (mild) was used at day-old age for 'priming' of all the birds and subsequently, combination of live (intermediate) and/or inactivated vaccines was tested in three groups. One group served as control. The response of birds, vaccinated once or twice with live intermediate vaccine was not satisfactory as indicated by low levels of antibodies even after vaccination. On challenge, some birds showed clinical symptoms and bursal damage. The group in which birds received inactivated vaccine, at seven days of age and live vaccine at 14 and 28 days of age, showed significantly (P <0.05) higher levels of antibody. On challenge, the birds did not show clinical symptons and mortality, but still these birds were not prevented from infection because the bursal danage was apparent indicating inadequate response against virulent IBDV. Overall studies indicated the presence of highly virulent IBDV in sone pockets of Gujarat State. Therefore, it is important to locate such pockets at an earliest to prevent possible spread of highly virulent IBDV and carry out effective vaccination coupled with strict biosecurity measures, where immunization has failed probably because of increased virulence of IBDV. Serological monitoring of progeny flock is necessary to determine when MA in chicks decline to levels that the vaccine can overcome. Without this information, it is very difficult to control highly virulent IBDV.ThesisItem Open Access ANTIGEN DETECTION, PATHOGENICITY AND PERSISTENCE OF MATERNAL ANTIBODIES OF INFECTIOUS BURSAL DISEASE VIRUS(AAU, Anand, 1995) Abraham, Reena; Kher, H. N.Infectious bursal disease is an acute or more commonly a subclinical viral disease of young chickens characterized by lymphocidal effects in the lymphoid organs, especially in the bursa of Fabricius. The disease is known to cause immunosuppression, vaccinal failure and surfacing of latent and subclinical concurrent infection in the infected bird. Present study was aimed at the antigen detection, pathogenicity and persistence of maternal antibodies of infectious bursal disease virus (IBDV). The bursa samples were collected from the dead or ailing birds with specific IBD lesions routinely obtained at the Department of Pathology and were tested for the presence of the viral antigen using agar gel diffusion test (AGDT). The samples obtained from Anand, Karamsad, and Undach gave positive line oi precipitation with known positive serum. The isolates designated as AND (Anand), KAM (Karamsad) and UND (Undach) on the basis of the area from where these samples were obtained, were compared with a reference isolate BAN (Bangalore) for the pathogenicity study. Clinical symptoms were observed in one or two birds -from each group followed by death. Rest of the birds were normal till the end of the observation period . The bursa of Fabricius was found enlarged on the third day PI with gradual atrophy setting in from seventh day PI in all the infected groups. Spleen showed slight enlargement on seventh day PI. Thymus was found to be enlarged on 11th and 14th day PI. The bursa to body weight indices showed significant difference at different intervals. The indices showed that the bursa to body weight ratio in all the infected groups was about two times as compared to that of control on third day PI and from fifth day PI, there was a decrease in this ratio in all the infected group till the end of the observation period suggesting atrophy, The histopathological lesions were mainly seen in bursa of Fabricius (BF) in the form of marked inter and intrafollicular oedema and mild to moderate depletion of lymphoid cells on the third day PI. Mild increase in the interfollicular connective tissue proliferation along with heterophilic infiltration was also seen. The changes became severe on fifth day PI. On seventh day PI, the bursal follicles were atrophied with severe depletion of the lymphocytes in cortex and medulla. On 11th and 14th day PI, large cystic follicles with mononuclear cell infiltration into the interfol1icular area were observed. The spleen lesions were in the form of mild depletion of lymphoid cells along with focal areas of coagulative necrosis and reticulo-endothelial (RE) cell hyperplasia. The thymus and caecal tonsils revealed same type of lesions as spleen. The kidney revealed acute renal congestion and presence of lymphoid foci. The lesions were very mild in the AND and KAM groups of birds. The antigen was detectable in UND group on third day PI and BAN group on third and seventh day PI by AGDT. Using quantitative AGDT, serum antibodies were detected from seventh day PI onwards in the local isolate infected groups and from fifth day PI in the reference isolate infected group. 'The antibody titres showed gradual increase in all groups till the end of the observation'period. For immunosuppressive study, each infected group was vaccinated with sheep erythrocytes and subsequently at weekly interval birds from each group were screened for presence of antibody using HA test. Overall antibody level of control group was significantly higher (P < 0.01) from treatment means of infected group. Among BAN, KAM and AND isolates infected groups, mean HA titres did not show significant difference, but in UND isolate infected group the mean titre was significantly higher than other groups. Further, the infected birds were vaccinated with 'F' vaccine of NDV and each group was screened at weekly interval for presence of antibody using HI test. The HI titres of all the infected groups were significantly lower than that of control group at second and third week suggesting immunosuppressive effect of these isolates. The titres in AND and KAM groups were significantly lower than that in UND and BAN groups during this period indicating their more immunosuppressive effect. Only the UND isolate was adapted to the chick embryos producing mortality in four out of six chick embryos when inoculated via CAM route at fourth passage level. The embryoij were stunted with cutaneous haemorrhages in the cerebral area and on the toes. The other isolates did not adapt to embryos evenafter four passages. The maternal antibodies were found to persist in the chicks hatched from vaccinated parental flock upto 20 days of age as ascertained by ELIBA and quantitative AGDT. The maternal antibodies with the quantitative AGDT titre 1:8 and ELISA titre +3, were found to be protective only upto 15 days of age in chicks against IBDV infection.