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Theses

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1994 - 19963
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Subject: Veterinary Microbiology × Author: KAU × End date: 1996 × Start date: 1990 × Type: Thesis × Thesis Type: M.V.Sc. ×
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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
    Cerytain plasmid-mediated characters of staphylococci isolated from bovine mastits
    (Department of Microbiology, College of Veterinary and Animal Sciences, Mannuthy, 1996) Anil Kumar, M; KAU; Punnose, K T
    Twenty – six staphylococci were isolated from 70 cases of clinical / sub – clinical bovine mastitis. They were characterized by various biochemical tests and biotyped using coagulase production, haemolysin production, pigment production, Tween – 80 hydrolysis and casein hydrolysis. These 26 isolates comprised 19 biotypes of which, most preponderating one was biotype – B comprising of 5 isolates. The reliability of biotyping in distinguishing the isolates was found to be 73.08 per cent. The antibiogram study revealed that chloramphenicol and vancomycin were cent per cent effective. Cloxacillin, nitrofurantoin, pefloxacin and polymixin – B were also effective. Ampicillin and nalidixic acid were found to be least effective. The reliability of this method was found to be 96.15 per cent. Resistogram study revealed that maximum degree of resistance was noticed against barium chloride and potassium permanganate. All the isolates were found to be sensitive to antimony trichloride, cetrimide, copper sulphate, ferrous sulphate, iodine and potassium tellurite. The reliabiling of resistogram study was found to be 76.92 per cent. Production of haemolysin and resistance to antibiotics were found to be plasmid – mediated. Correlation between resistances to certain antibiotics and metal salts/chemical agents was also found. The plasmid profiling revealed only 16 isolates carrying plasmids. No plasmid was found common to in all the isolates. The maximum number of plasmids in an isolate was five, and this isolate carried both the largest and smallest plasmids. The reliability of plasmid profiling was 61.54 per cent. Conjugation studies revealed transfer of ampicillin, penicillin, streptomycin, erythromycin and gentamicin resistances and beta- haemolysin production to the recipient. But alpha – haemolysin was not transferred. Protoplast fusion studies revealed the expression of only ampicillin, pencillin and streptomycin resistance and alpha – haemolysin production, by the biparental strains. Determination of Numerical Index of Discrimination indicated that antibiogram typing and all its combinations were having the maximum ‘D’ value of one. Plasmid profiling was having the least value, i.e. 0.862. So it is suggested that antibiogram typing and its combinations can be used in differentiating and identifying the staphylococci causing bovine mastitis, more accurately.
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    ThesisItemOpen Access
    Structural analysis of Infectious bursal disease virus isolates from clinical cases in vaccinated and unvaccinated birds
    (Department of Microbiology, College of Veterinary and Animal Sciences, Mannuthy, 1995) Vengadabady, N; KAU; Sulochana, S
    Field cases with history suggestive of infectious bursal disease (IBD) were screened for confirmation by Agar gel diffusion test (AGDT), using reference antigen and antisera received from Madras Veterinary College. From the positive cases, 4 isolates, two each from unvaccinated (PKD, EKM) and vaccinated (THR, KAN) flocks and an avirulent vaccine strain (VAC) were used for structural analyses and antigenic relationship studies. The percentage of mortality of the embryos infected by these strains ranged between 50 – 100 per cent, during the third and fifth day of inoculation, in the fourth passage. The lesions produced were cutaneous haemorrhages all over the body, congestion and thickening of CAM. Enlarged bursa and typical yellowish green discolouration of liver with brown patches were also noticed. All the five isolates were propagated in chicken embryo fibroblast culture, in which cytopathic changes characterised by rounding and subsequent detachment was seen from the third passage onwards. The chicks infected with field isolates revealed mildclinical symptoms. The lesions noticed after sacrificing them on the third day were moderately swollen gelatinous bursa with slight haemorrhage in some of them. Chicks that received vaccine strain revealed only mild lesion. The viral strains by SDS – PAGE revealed that all the field isolates contained nine identical polypeptides with molecular weights of 86 KD (VP2), 77 KD (VP4), 73 KD (VP5), 62 KD (VP6), 52 KD (VP7), 47 KD (VP8), 39 KD (VP10), 36 KD (VP11) and 32 KD (VP12). The vaccine strain resolved 11 peptides of whichthree, namely VP1 (93 KD), VP3 (80 KD) and VP9 (43 KD), were absent in the field isolates, but it lacked VP7 (52 KD). Mild difference in the molecular weights of VP6 and VP12 were also noticed between the field isolates and vaccine strain. Nucleic acid analyses in agarose gel showed two bands for all the five isolates without any difference in their migration pattern. Antigenic relationship of the IBDV isolates was studied by AGDT, CIE and IE. All the four isolates produced only one precipitation line against the antiserum and this precipitation line was identical to the one produced by the vaccine strain. From the observations made, the possible reasons for breakdown of immunity and a schedule of vaccination to overcome this situation have been discussed.