Cross-protection study of the nine serovars of Haemophilus paragallinarum in the Kume haemagglutinin scheme

The cross-protection and haemagglutination-inhibition antibodies present in chickens vaccinated with one of the nine currently recognized Kume haemagglutinin serovars of Haemophilus paragallinarum were investigated. The results confirmed the widely accepted dogma that serogroups A, B, and C represent three distinct immunovars. Within Kume serogroup A, there was generally good cross-protection among all four serovars. However, within Kume serogroup C, there was evidence of a reduced level of cross protection between some of the four serovars. The haemagglutination-inhibition antibody levels generally showed the same trend as with the cross-protection results. This study suggests that some apparent field failures of infectious coryza vaccines may be due to a lack of cross-protection between the vaccine strains and the field strains. Our results will help guide the selection of strains for inclusion in infectious coryza vaccines.

Successful management of colletotrichum crown and stolon rot in runner production in sub-tropical Australia

Crown, stolon, and petiole rots caused by Colletotrichum gloeosporioides (C.g.) were first identified in runner beds of the Queensland Approved Runner Scheme (QARS) in February 1989. The outbreaks occurred annually from 1990 to 1994. Minor losses in subsequent fruit crops occurred from 1990 to 1993, with 50% post-establishment losses occurring on fruit farms in southeast Queensland in 1994. The objective of this work was to provide a control strategy for the disease that would give stability to the QARS. Runner-bed trials in 1993-1994 showed that Octave® (462 g/kg prochloraz as the MnCl2 complex) was highly effective in reducing the incidence field symptoms and laboratory recovery of C.g. from symptomless petioles. A simple detached petiole laboratory test for measuring fungicide efficacy in runner bed trials and for laboratory screening of fungicides, is described. Scheme protocols were changed to require that only foundation plants from tissue culture were allowed onto QARS sites. These were to be symptomless and to have tested negative for the presence of C.g. The application of Octave® at fortnightly intervals in all QARS nurseries has reduced the level of visible symptoms and the laboratory recovery of C.g. from symptomless petioles to almost zero.

Development of a multi-locus sequence typing scheme for avian isolates of Pasteurella multocida.

A total of 63 isolates of Pasteurella multocida from Australian poultry, all associated with fowl cholera outbreaks, and three international reference strains, representing the three subspecies within P. multocida were used to develop a multi-locus sequence typing scheme. Primers were designed for conserved regions of seven house-keeping enzymes - adk, est, gdh, mdh, pgi, pmi and zwf - and internal fragments of 570-784 bp were sequenced for all isolates and strains. The number of alleles at the different loci ranged from 11 to 20 and a total of 29 allelic profiles or sequence types were recognised amongst the 66 strains. There was a strong concordance between the MLST data and the existing multi-locus enzyme electrophoresis and ribotyping data. When used to study a sub-set of isolates with a known detailed epidemiological history, the MLST data matched the results given by restriction endonuclease analysis, pulsed-field gel electrophoresis, ribotyping and REP-PCR. The MLST scheme provides a high level of resolution and is an excellent tool for studying the population structure and epidemiology of P. multocida.

Sorghum Midge Tested Scheme

Scheme provides independant testing and official industry midge resistance rating of pre-commercial sorghum varieities. Continuation of current project.

Sorghum Midge Testing Scheme

Scheme provides independant testing and official industry midge resistance rating of pre-commercial sorghum varieities.