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1980 - 198921990 - 19941
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Subject: Microbiology × Author: KAU × End date: 1995 × Thesis Type: M.V.Sc. ×
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    ThesisItemOpen Access
    Immunogenicity of an indigenous isolate of newcastle disease virus and Its usefulness as a vaccine strain
    (Department of microbiology, College of veterinary and animal sciences, Mannuthy, 1983) Murugan, M R; KAU; Suloohana, S
    The newly isolated mesogenic strain of Newcastle disease virus (NT) from an ailing mynah was studied in detail with particular reference to its biological characteristics, pathogenicity and immunogenicity. The results of various studies were compared with that of Komorov strain, a known mesogenic strain. The titer attained in developing chick embryos, mean death time of inoculated chick embryos at terminal dilutions, neuropathogenicity index in day old chicks and intravenous pathogenicity index were 109.5 /0.2 ml, 87 hours 0.63 and 0.00 respectively for the MT strain. The above values in order were 1010.5/0.2 ML, 76.5 hours, 1.16 and 0.000 for the Komorov strain. The infectivity of MT strain was labile at 560C for 10 minutes and the haemagglutinin was completely lost within five minutes. On the other hand the infectivity and haemagglutinin of K strain were comparatively resistant. Strain MT was pathogenic to day old chicks in which 26.6% mortality was noticed. In recovered chicks sufficient HI antibodies were seen and all of them withstood challenge. Although comparable results were obtained for Komarov strain, it was less pathogenic to day old chicks. Though 23.3% of chicks manifested clinical symptom only 3.3% died and the remaining birds recovered. In three weeks old chicks MT and K strain were found to be nonpathogenic either by S/C or oculonasal route. The inoculated chicks were immune when challenged six weeks later. Even in six weeks old chicks having no base immunity no post-inoculation reactions could be detected. All the chicks showed a rise in antibody titer reaching the peak level by the end of the third week and were resistant to challenge after six weeks. In chicks aged six weeks having a base immunity with strain were also free from any post infection reaction either by I/M or S/C route or inoculation. Chicks in both the groups produced HI antibodies and was always higher in those received infection by I/M route. The peak titers were obtained at the end of the third week and then declined. Though the titers were low by the end of the 6th week all the chicks were resistant to ND when exposed to a virulent virus. 2.9% of the chicks that received K strain by I/M route showed post inoculation reaction and died of ND. The remaining chicks and those in the S/C group behaved the same way as those received NT strain. Though the antibody response of chicken to MT and K were not statistically significant in all the three experiments, MWU test revealed that MT has a significantly higher immunogenic effect than K as the former always had a higher means than the latter. The ability to infect in contact chicks was also investigated. Strain MT was less efficient in this property giving only 25% to 28% transmission. On the other hand K strain revealed significantly higher transmissibility as it could spread to 62.5 to 75% of the inoculated in contact chicks. The mesogenic strain MT is quite safe in chicks of three weeks of age and above. It is also a good immunogen producing HI antibodies which protected the chicks from challenge even after six weeks. However the strain can be recommended as a vaccine strain only after further field trials and its effects on egg production are worked out.
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    ThesisItemOpen Access
    Comparison of serological tests for the detection of leptospira antibodies in immunised animals
    (Department of microbiology, College of veterinary and animal sciences, Mannuthy, 1980) Ravikumaran Nair, R; KAU; Abdulla, P K
    Leptospirosis is a widespread disease of man and animals and is of considerable economic importance besides being a public health problem. The leptospira infection in man and animals may be confirmed either by isolation of the organisms or by detection of specific antibodies in the serum and tissues of infected animals. Isolation of Leptospira is time consuming and beyond the scope of many diagnostic laboratories. In the present study the sensitivity of passive haemagglutination test was compared with the established microscopic agglutination test utilizing rabbit hyperimmune serum as the source of antibody. Leptospira serotypes were grown in Korthof’s medium enriched with 10% haemolysed rabbit serum. By 7 – 10 days satisfactory concentration of the organisms was obtained and was used for MA test. Passive haemagglutination test was carried out employing ethanol extracted antigen from concentrated leptospiral cultures. The PHA test was carried out after determining the optimum dilution of antigen required to sensitize sheep erythrocytes. Hyper immune sera to both serotypes were raised in rabbits by a series of intravenous inoculations. Serum samples for antibody titration was collected at weekly intervals from seven days following the first injection till the 49th day. Antibody titration by MA and PHA tests have shown that all the three animals inoculated with L. autumnalis had a uniform titre of 1:400 on the seventh day whereas the other three animals inoculated with L. pyrogenes showed a low titre of 1:100 by MA test. The PHA titre of both the groups remained the same ie 1:5. The maximum titre of 1:28000 for L. autumnalis was attained on the 21st day and remained unchanged until 35th day. The maximum PHA titre was attained only on 35th day (1:160). The rabbits inoculated with L. pyrogenes showed a maximum titre of 1:3200 by MA and 1:80 by PHA. The results obtained tend to show that PHA titres after reaching the maximum level remained detectable for longer period when compared to MA titres. Erythrocyte sensitizing substance from both the serotypes and the sera samples collected periodically from immunized rabbits were preserved at – 200 C at varying length of time upto three months. There was no deterioration in the stability or potency of ESS or sera on storage.
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    ThesisItemOpen Access
    Characterization of Campylobacter jejuni isolated from pigs and man
    (Department of Microbiology, College of Veterinary and Animal Sciences, Mannuthy, 1994) Raju, P V; KAU; Madhusoodanan Pillai, R
    Twenty six rectal swabs collected from piglets below two months of age with diarrhoea/enteritis when culturally screened yielded 11 isolates of Camplobacter jejuni. Thirty two rectal swabs from children below five years of age with diarrhoea/enteritis when processed for the isolation of etiological agent, resulted in the recovery of one strain of C. jejuni. Sonicated C. jejuni antigen prepared from the selected strains of C. jejuni from porcine and human origin were found suitable for sensitization of gluteraldehyde stabilized sheep RBC for serum antibody monitoring. The sonicated antigen retained its affinity to sheep RBC even after six months of storage at – 600 C. Gluteraldehyde stabilization was found to be a suitable method for the preservation of SRBC. Gluteraldehyde stabilized SRBC stored at 40 C upto a period of three months did not show any reduction in the sensitization property, as evidenced from the PHA titre. One hundred and fifty microliters of C. jejuni antigen whose protein concentration adjusted to 2 mg/ml was found to be the optimum level for sensitisation of a suspension made from three millilitres of packed SRBC. The optimum level of SAPA cells required in the seromonitoring of C. jejuni specific antibodies by SAPA – AMHA test was found to be 0.1 per cent. Cross titration assay employing homologous and heterologous antigens of C. jejuni and the hyperimmune sera indicated that there was antigenic relationship between porcine and human strains. The results also point to the probable prevalence of different antigenic components in varying proportions in different strains from various sources. In the present investigation, 50 serum samples from pigs were monitored for the presence of C. jejuni specific antibodies by PHA and SAPA – AMHA. PHA detected 48 per cent cases as positives compared to 54 per cent by SAPA – AMHA. Statistical analysis clearly indicated that SAPA – AMHA is superior to PHA in screening C. jejuni specific antibodies. The result of the present study indicated that SAPA – AMHA test could advantageously replace the conventional PHA for serological diagnosis of animal and human Campylobacteriosis. Efforts were also made in this study to find out the change in PHA titre with homologus and heterologous antigens employing sera before and after adsorption with unsensitised SRBC to remove the non specific antibodies. Statistical analysis of the results showed that for performing PHA, homologous antigen should be preferred over heterologous antigen and when homologous antigen were used, adsorption of sera with stabilized unsensitised SRBC had no significant effect of PHA titre. Attempts were also made to study the in vitro antimicrobial sensitivity patterns of the 12 C. jejuni isolates by standard disc diffusion technique. The results indicated all the C. jejuni isolates were sensitive to chloramphenicol, gentamicin and nalidixic acid, irrespective of their source/origin. Eventhough none of the C. jejuni isolated in this study was resistant to erythromycin, only 83.3 per cent of the isolates showed a sensitive zone of inhibition, while, 16.7 per cent showed an intermediary zone of inhibition. C. jejuni isolates recorded 83.3 per cent sensitivity to furazolidone, 75 per cent to streptomycin and 58.3 per cent to ampicillin. Fifty per cent of the isolates showed resistance to oxytetracycline. Of the ten antibiotics tested, 16.6 per cent of the organism were sensitive to penicillin. C. jejuni recorded highest resistance to sulphadiazine as only 8.3 per cent of the organisms were sensitive to sulphadiazine.