Development Of Experimental Inactivated Vaccine For Bovine Leptospirosis
Loading...
Date
2009
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Tamil Nadu Veterinary and Animal Sciences University
Abstract
Sero survey against leptospirosis by MAT was conducted on 3605 serum
samples collected from cattle and buffaloes suffering from abortion, repeat
breeding, jaundice haemorrhagic mastitis and apparently healthy animals from 16
different districts of Tamil Nadu, 12 different districts of Andhra Pradesh and a
private farm in Gujarat state. Seropositivity was found to be 40.39 per cent, 50.21
per cent and 34.74 per cent among cattle and 75.66 per cent, 68.64 per cent and
54.14 per cent among buffaloes in Tamil Nadu, Andhra Pradesh and Gujarat
respectively.
Seropositivity was more in exotic pure breeds (50.00 per cent), followed by
indigenous pure breeds (34.38 per cent) and cross breeds (32.74 per cent) cattle.
Meanwhile among buffaloes, seropositivity was more in Murrah (58.25 per cent),
followed by Pandharpuri (40.91 per cent) and Jaffrabadi (37.50 per cent)
respectively. Males were more positive than females.
A total of 555 sera samples from different animal conditions which were
MAT positive were found for have elevated levels of bilirubin, SGOT and SGPT.Only 115 sera samples from different clinical condition like abortion repeat
breeding, jaundice and haemorrhagic mastitis and apparently healthy animals were
screened for the presence of Leptospira specific antibody and antigen. Sixty four
(55.65 per cent) samples were positive for antibody by MAT whereas 26.09 per
cent samples were positive for Leptospira by DFM and 20.87 per cent samples
were positive for pathogenic leptospiral DNA by PCR test.
Out of 30 sera
samples screening for isolation, 9 isolates of australis (5), hebdomadis (3) and
ballum (1) were obtained. In sequence analysis no significant variation could be
observed with reference strains.
Since the serovars australis, ballum, hardjo, hebdomadis and pomona were
consistently prevalent, they were selected as seed bacteria for the preparation of
Leptospira experimental vaccines. Formalin inactivated two different kinds of
adjuvanted pentavalent vaccines were prepared. Vaccine I was adjuvanted with
Montanide ISA 206 and vaccine II was adjuvanted with Aluminium hydroxide gel.
Both the experimental vaccines were found to be potent and safe. Duration of the
immunity for both the vaccines was studied in rabbits under experimental
condition and in cattle under field condition. High antibody titre of 6.84 log 2 to
9.64 log 2 with vaccine I (Montanide adjuvanted) and 5.64 to 7.44 log 2 with
vaccine II (Aluminium hydroxide adjuvanted) were found at 180 days in rabbits.
For cattle, GM – MAT titres of 6.84 log 2 to 7.69 log 2 were observed against
vaccine – I at 150 days and such titres were seen with vaccine – II at 120 days.
Thus vaccine I was found to be a better vaccine than vaccine II. However both the
vaccines showed high immune response of 5.64 log 2 at 6 months of immunization.
Description
Keywords
Leptospirosis, Seroprevalence, Isolation, Microscopic Agglutination test, Dark Field Microscopy, Polymerase Chain Reaction, Vaccines