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Theses

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1992 - 19944
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Subject: Veterinary Microbiology × Author: KAU × End date: 1994 × Start date: 1990 × Type: Thesis ×
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    ThesisItemOpen Access
    Antigens of pasteurella multocida isolates from rabbit and their immunologencity
    (Department of microbiology, College of veterinary and animal sciences, Mannuthy, 1994) Manoharan S; KAU; Jayaprakasan, V
    Two rabbit strains viz. R9 S and R23 S and a bovine vaccine strain P – 52 which were maintained in virulent form, were used for the preparation of three forms of antigen viz., heat inactivated crude extract, KSCN extract and sonicated antigen. These antigens were chemically analysed for protein and carbohydrate contents and were found to be higher in the sonicated antigen preparation irrespective of the source. In SDS – PAGE analysis, the profiles discerned by heat inactivated crude extract, KSCN extract and sonicated antigens were four, five and six protein bands with molecular weights lesser than 68 kDa while the KSCN extract and sonicated antigen presented an additional protein band with molecular weight higher than 68 kDa. Three types of antigen of P. multocida were characterized and analysed for the inter relationship and the immunogenic potential in mice. Antiserum was raised against each antigenic preparation from the three strains in rabbits and used for serological study. In AGPT and immunoelectrophoresis the serum developed multiple precipitin lines and arcs respectively when reacted against the three homologous and two heterologous antigens in which a few were identical to the heterologous antigens. The results revealed stronger serological relationship between the two rabbit strains than with the cattle strain and the heterogeneity of the sonicated antigen. The antibody titre in each antiserum was measured by IHA using the sensitized GA – SRBC/T – GA – SRBC and the titres were more in the homologous antiserum and high titre for the heterologous serum was seen with the sonicated antigen. The LD50 determined for the three strains R9 S, R23 S and P- 52 was found to be 3 x 104 , 3 x 103 and 3 x 105 bacteria. Immunogenic potential of the three antigens and an adjuvanted sonicated antigen were tested in mice by giving two doses of vaccine at 14 days interval and challenging on 21st day with homologous and heterologous strains. A higher percentage of protection was conferred by homologous strains and it was cent per cent (100%) with sonicated antigen. The percentage of protection against challenge with heterologous strains was low. An elaborated study on immunity trials with these immunogens is needed before recommending the R23 S as a candidate vaccine strain.
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    ThesisItemOpen Access
    Assessment of immunity to duck plague virus (duck virus enteritis)
    (Department of Microbiology, College of Veterinary and Animal Sciences, Mannuthy, 1993) Diwakar Dattatrayrao, Kulkarni; KAU; James, P C
    During 1991, six outbreak clinically suspected to be duck plague (DP) with 33 per cent morbidity and 26 per cent mortality were investigated Duck plague virus was isolated from each outbreak. The isolates were able to produce the lesions and death of the duck embryos but failed to kill the chicken embryos during initial passages. One of the strains, named DP-S was partially attenuated by 10 passages in chicken .embryos following 20 passages in duck embryos. Though the attenuated strain did kill ducks, its pathogenicity index was reduced from 1.9 to 1,23. The isolate DP-S under transmission electron microscope revealed virions of herpes virus morphology. Two DP vaccines - commercial vaccine and lab-adapted vaccine having virus titres 0.74 and 3.5 log 10 ELD 50/ml respectively, were separately inoculated into four groups of ducklings respectively, two groups receiving single dose and two receiving double dose of corresponding vaccines at an interval of four weeks. Another group of ducklings was kept as control without vaccination. Three ducks in each group were challenged with virulent DPV at four,eight and 20 weeks post-vaccination. The birds in all the five groups were screened at regular intervals for studying the immune response by virus neutralization (VN), leucocyte migration-inhibition (LMI) and passive haemagglutination (PHA) test The challenged and survived birds were screened for the carrier status of DPV by examination of their rectal swabs for virus isolation. In an organized farm, 180 ducks were given commercial vaccine at one year of age and were screened for VN antibodies, LMI response and PHA titres before and eight weeks post -vaccination. Randomly selected two birds were challenged six weeks post-vaccination. The findings of the study are briefly listed as under: Six duck plague outbreaks were investigated, the virus isolated, and characterized. It was partially attenuated in duck and chicken embryos. The commercial, vaccine could elicit very poor immune response as compared to laboratory adapted vaccine. The immunity could not last long even upto eight weeks in single vaccination and 20 weeks in double vaccination.
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    ThesisItemOpen Access
    Characterization of plasmids of Escherichia coli isolated from mastitis
    (Department of Veterinary Microbiology, College of Veterinary and Animal Science, Mannuthy, 1993) Avinash Ganpatrao, Karpe; KAU; Punnoose, K T
    Escherichia coli. were isolated in 15.33 per cent cases of mastitis. Of the 46 E. coli isolated 43 were resistant to one to nine antibiotics and three were sensitive to all the 13 antibiotics tested. The organisms were resistant to rifampicin (78.26%) followed by oxytetracycline (50%), tetracycline (37.78%), nalidixic acid (19.56%), co-trimoxasole (8.69%) and gentamicin (6.52%). All the organisms were susceptible to kamamycin and norfloxacin. Among the .multiple drug resistance oxytetracycline - rifampicin (OR) resistance was noticed in 76.2% cases. Twenty-six different patterns of antibiotic resistance were noticed among 43 E. coli isolates giving a reliability of 60.46 per cent in differentiating the isolates. Hence, antibiogram could only be used as an adjunct to plasmid profiling in epidemiological studies. The resistograms revealed cent per cent resistance to lead, followed by antimony (32.6%), copper (30.43%), silver(19.56%) and cetrimide (2.17%). All the isolates were sensitive to cadmium and mercury. Among the 46 E. coli isolates, 9 different resistogram patterns were obtained giving reliability of 19.56 per cent in differentiating the strains. A correlation between the antibiotics and heavy metal ac; lead an+-imcny and copper, was observed inresistance such as leaa, descending order. of the forty-six E. coli isolates three (6.52%) were hemolytic on sheep blood agar. Two of the three hemolytic strains were also enterotoxigenic. Thirteen of the 46 (28.26%) E. coli isolates were enterotoxigenic, when tested by rabbit ligated ileal loop assay. Two of the thirteen (15.38%) enterotoxigenic isolates were also hemolytic. Fourteen of the 24 (58.33%) drug resistant E. coli transferred drug resistance against one or more antibiotics to the recipient organism. In none of the cases the furazolidone resistance was transferred. All the three hemolytic E. coli isolates transferred the hemolytic character by conjugation indicating the plasmid borne nature of hemolysin production. None of the enterotoxin producing E. coli could transfer the character to recipient by conjugation.
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    ThesisItemOpen Access
    Characterisation of Pasteurella multocxda isolates from rabbits
    (Department of Microbiology, College of Veterinary and Animal Sciences, Mannuthy, 1992) Sheela Yohannan; KAU; Jayaprakasan, V
    One hundred and twelve rabbits were examined during this study which included 76 apparently healthy and 36 ailing/ dead rabbits. The live animals comprised 20 young and 56 adult animals, of which, 32 were of New Zealand White, 16 Grey Giant, seven Soviet Chinchilla" and 21 cross bred. This included both healthy and sick animals. Of the 36 ailxny/dead rabbits, 26 of them were of Nev/ Zealand White, six of Soviet Chinchilla and four of Grey Giant. This included 20 young and 16 adult animals. Pasteurella multocida could be isolated from five adult New Zealand White and one adult Grey Giant which died of respiratory infection. Gross pathological lesions observed in post mortem examination were typical haemorrhages in the trachea, haemorrhages and abscessation in lung and necrotic foci in liver. All the six isolates were gram negative coccobacilli, non motile and produced catalase. Two isolates were oxidase negative and four oxidase positive, grew anaerobically, utilised glucose fermentatively and none produced hemolysis of sheep red blood cells. The isolates were positive for nitrate, indole and potassium cyanide except for one isolate which was nitrate negative and two were indole negative. All were negative for hydrogen sulphide production, urease and gelatin hydrolysis. Only one isolate was positive for growth on ONPG. Majority of the sugars were fermented by these isolates. These isolates were tested for their pathogenicity in mice and rabbits. Intra peritoneal injection of one millig litre of an overnight culture containing 10 bacteria/ml, killed mice between 24-72 h post inoculation and the organism could be re-isolated from the dead animals. When rabbits were intra-nasally inoculated, with 0.5 ml of overnight culture containing 3.2 x 10^ bacteria, none of the isolates could establish clinical infection. Though the inoculated rabbits were apparently normal, one isolate colonised within the nares of the rabbit and was shedder for a period of seven days, while the other rabbits inoculated with the remaining five isolates were shedders only upto 48 h.