Current Research Projects - Cattle
Bovine Johne's Disease: improved diagnosis and prevention
Pathogenesis of Acorn Calf Disease
Dam mutants of salmonella
Bovine Johne's Disease - basic and applied research for improved diagnosis and prevention P.PSH.0297
Farm Animal & Veterinary Public Health Staff
Professor Richard Whittington
Dr Douglas Begg
Dr Kumudike de SIlva
Dr Karren Plain
Dr Auriol Purdie
Ms Nicole Carter
Ms Sophie Hoft
Mr Craig Kristo
Mrs Rebecca Maurer
Mr Jesse McIvor
Mr Nobel Toribio
Mrs Anna Waldron
Mrs Ann-Michele Whittington
PhD Students
Ms Satoko Kawaji
Mrs Kate Bower
Mr Ratna Gurung
Ms Syamala Thirunavukkarasu
National Collaborators
Dr Ian Marsh, NSW Separtment of Primary Industries
Elizabeth Macarthur Agricultural Institute
International Collaborators
Dr Jayne Hope, Compton Institute, UK
Dr Gregers Jungerson, Danish veterinary Laboratory
Dr Yasuyuki Mori, National Animal Health Institute, Japan
Summary
Bovine Johnes disease (BJD), caused by Mycobacterium avium subsp. paratuberculosis is a significant issue for the dairy industry in south eastern Australia and a sporadic problem in beef cattle. Efforts to reduce the within-herd prevalence of BJD within the dairy industry have been quite successful using conventional technologies, and concomitant efforts to prevent spread to the beef cattle sector also appear to be well accepted by the industry. A vaccine for BJD may soon be available; this is likely to be a valuable tool to reduce prevalence in heavily infected dairy herds.
Internationally, BJD is considered to be a significant threat to the livestock sector. Several studies have confirmed direct economic loss, but a greater threat exists because of a perceived link with Crohns disease in humans, and the need to apply the precautionary principle in order to ensure future market access for livestock products. Public health authorities in many developed countries have adopted a neutral position on the possible link between M a paratuberculosis originating in livestock and the occurrence of the organism and disease in humans. However there are large research programs on BJD in the EU/Europe, Japan and North America and smaller research programs in many other places. For market access insurance, Australia needs to be engaged with R&D at an international level. Currently there is very little active research on BJD in Australia. A very large research program on ovine Johnes disease (OJD) (National OJD Control and Evaluation Program) has been completed and has led to substantial capacity in this field of research that can now be applied to BJD.
This project addresses substantial opportunities:
Australia is in a good position to capitalise on research advance in BJD that will come from the EU and North America because of close scientific and professional collaboration and interactions through the International Association for Paratuberculosis (IAP) and the Johnes Disease Integrated Program (JDIP). Australia can expect to obtain greater understanding of the causative bacterium and its evolutionary background, and better herd diagnostic tools, for example environmental sampling. These advances will become available without direct investment, but may be limited in extent or applicability in the Australian context.
Australia currently has a large research program on pathogenesis and early detection of OJD (MLA project OJD.031). This project has resulted in collaborative ties with researchers in Scandanavia (BJD), New Zealand (JD in sheep and deer) and Japan (BJD). The techniques and infection models developed through the project are directly applicable to BJD research.
Source of Funding
Meat & Livestock Australia
Project Timeframe
January 2008 - January 2011
Studies of the Epidemiology and Risk Factors Involved in the Pathogenesis of Acorn Calf Disease in Australia B.AHE.0004
Farm Animal & Veterinary Public Health Staff
Dr Jenny-Ann Toribio
Professor Peter Windsor
PhD Student
Mr Peter White
Summary
This project is being undertaken to improve the understanding of the epidemiology of the acorn calf disease syndrome, particularly its geographic and temporal distribution, and risk factors associated with disease occurrence.
The project will involve a nationwide survey of public and private veterinarians who have been involved in rural practice for the past five years requesting information about affected calves that meet the case definition for acorn calf disease and about cases that resembled acorn calf disease including: number affected, clinical signs, gross pathology, location, date and breed. The survey will provide, for the past five years: a crude estimate of the annual prevalence of acorn calves in Australia; and, a description of the spatial-temporal distribution of acorn calves.
A retrospective examination will also be undertaken of case records of previous outbreaks in Australia. This study will provide confirmation of the annual prevalence of confirmed cases of acorn disease in Australia; spatial-temporal distribution of confirmed cases; and, information about potential risk factors common among confirmed cases.
A case-control study will be done on properties with confirmed cases of acorn calf disease since 2003 to identify case and control herds on each affected property, and at least one neighbouring property as a control property. Face-to-face questionnaires will be administered with the owner/manager of each affected and control property to collect information about each property and its management during the gestation period of affected calves. Risk factors associated with the occurrence of acorn calf disease will be identified.
Source of Funding
Meat & Livestock Australia
Project Timeframe
April 2007 - November 2009
Dam mutants of S. typhimurium as modified live vaccines in calves
Farm Animal & Veterinary Public Health Staff
Associate Professor John House
National Collaborators
- Dr Keith Walker
Dr Michael Hornitzky
Elizabeth Macarthur Agricultural Institute (NSW DPI)
International Collaborators
Dr Michael Mahan & Mr Doug Heihoff
University of California, Santa Barbara
BSc(Hons) Student
Ms Jenny Mohler
Summary
Salmonellae are important pathogens of animals and man. They can cause food poisoning in humans upon consumption of contaminated meat and animal products. This proposal is based on our previous discovery that Salmonella typhimurium containing mutations in the dam gene that prevent DNA adenine methylase (dam) expression are virulent yet confer protective immunity as modified live vaccines in murine, avian, and calf models of typhoid fever.
One of the principal challenges to the development of commercial livestock vaccines is that multiple Salmonella strains are often endemic on farms, and traditional vaccines normally elicit protection against a single strain. We have recently shown that dam mutant Salmonella confer cross-protective immunity to multiple Salmonella strains when used as modified live vaccines in murine and avian models of typhoid fever.
Specific aims include:
- To determine if Salmonella dam mutant vaccines can confer cross-protective immunity against multiple Salmonella isolates in calves. A principal concern with all modified live vaccines is safety.
- To introduce additional attenuating mutations (e.g., aroA) to reduce the virulence capacity of the Salmonella dam vaccine without compromising efficacy in calves.
- To determine if Salmonella dam vaccines can be used as a platform for delivering passenger antigens to elicit protection against the cognate pathogen. We have chosen the Enterotoxogenic E. coli (ETEC) K99 fimbriae as a model passenger antigen since ETEC strains that express K99 fimbriae account for nearly all cases of ETEC infection in newborn calves and K99 fimbriae are a known immunogen that confers protective immunity against clinically relevant ETEC infections in calves and other species. The K99 fimbriae antigen from ETEC clinical isolates will be expressed in dam Salmonella. Vaccine efficacy will be assessed by elicitation of protective immunity against ETEC diarrheal disease in calves via passive colostral transfer of protective antibodies from vaccinated cows.
- To develop safe and effective vaccines against Salmonella infection of cattle, and to demonstrate that this vaccine platform may be used to express cognate antigens from other pathogens thereby promoting the health and productivity of livestock, reducing Salmonella contamination of livestock, livestock-derived food products, and enhancing food safety.
Source of Funding
United States Department of Agriculture
Project Timeframe
Continuing