Fresh Science

Researchers at the CSIRO’s Australian Animal Health Laboratory have developed a new test for foot-and-mouth disease that involves no infectious viral material and can differentiate between infected and vaccinated animals. This ‘DIVA’ test could transform how foot-and-mouth disease is controlled in future, because it’s so inexpensive and does not require infectious virus to produce the reagents.

The British government decided against using vaccines to control a major outbreak in 2001, because the tests available to them could not distinguish between infected and vaccinated animals. So, vaccinated animals would look like they were infected and would have to be treated in the same way. The outbreak was finally contained only after the slaughter of more than six million animals. Most were not infected.

“Our test is the first in the world to be built entirely from non-living materials produced in the laboratory,” says Janine Muller, who developed the test with CSIRO colleagues while completing her PhD. She is now a research scientist with the Victorian Department of Primary Industries.

“We have been able to build and manufacture the critical components of our test from the ground up. They are biochemical compounds, that are not alive, and can’t become infectious.”

“We unravelled the structure of an antibody to an important protein the virus injects into cells. We then generated its genetic template and used it to engineer the antibodies at the heart of the test.”

Foot-and-mouth disease, a highly contagious viral infection, is considered the most economically devastating disease affecting farm animals worldwide. It spreads rapidly and is a huge threat to trade. An outbreak in Australia would instantly shut down the meat and livestock industry and would cost between $8 and $13 billion in terms of lost production, trade and disease eradication.

The new test, which can pinpoint vaccinated animals, has application worldwide where the cost of producing reagents is a critical factor. The test itself is not used for primary diagnosis but in the control and recovery phase where material being tested is highly unlikely to be of an infectious nature and testing can be carried out at a lower level of biocontainment.

The test itself is a faster and more sensitive way of detecting the disease in livestock.

“This work is a great example of practical research that can provide real benefits to an industry,” says Terry Longhurst, Strategic Science Manager at Meat and Livestock Australia which, together the Australian Biosecurity Cooperative Research Centre, funded the research.

Janine Muller is one of 16 early-career scientists presenting their research to the public for the first time thanks to Fresh Science, a national program sponsored by the Federal and Victorian Governments.

Background

Production and application of recombinant antibodies to foot-and-mouth disease virus non-structural protein 3ABC

Adam J. Foord, Janine D. Muller, Meng Yu, Lin-Fa Wang, Hans G. Heine ⁎

CSIRO Livestock Industries, Australian Animal Health Laboratory, PO Bag 24, Geelong, Victoria, Australia

Received 20 September 2006; received in revised form 14 January 2007; accepted 15 January 2007

Available online 14 February 2007

Abstract

The stamping out of animals to control a foot-and-mouth disease (FMD) outbreak results in enormous livestock losses. The implementation of vaccination strategies can reduce these losses; however it complicates the process of establishing freedom from disease following an outbreak. The availability of quality diagnostic tests to differentiate infected from vaccinated animals (DIVA) is crucial to prove freedom from disease and allow for the resumption of trade in livestock products. All current foot-and-mouth disease virus (FMDV) DIVA tests rely on polyclonal or monoclonal hybridoma derived antibody reagents, which can be difficult to prepare and maintain in a quality-assured manner and in the quantities required for post-outbreak surveillance. Recombinant antibodies can be produced in large quantities at low cost in bacteria to guarantee the supply of a consistent and well-characterised reagent. The production of recombinant antibodies does not rely on animal immunisation and does not require the maintenance of viable hybridoma cell lines. In this study, phage display libraries of recombinant antibody single chain variable fragments (scFv) against FMDV were generated from chickens immunised with recombinant non-structural protein (NSP) 3ABC. A total of 32 positive clones were obtained that represented three distinctive genetic sequences, Chicken Recombinant Antibody-Foot-and-Mouth disease (CRAb-FM) 26, -FM27 and -FM29. Each was shown to bind the 3B region of the 3ABC protein. When evaluated in a C-ELISA format using sera derived from cattle, sheep and pigs representing naïve, FMDV-vaccinated or FMDV infected animals, CRAb-FM27 gave the best performance when paired with an E. coli-derived recombinant 3ABC, demonstrating the potential to be used as a species- and serotype-independent FMDV DIVA test. To our knowledge, this is the first FMDV DIVA test that uses both recombinant antibody and antigen derived from bacterial expression systems.

Abstract Crown Copyright © 2007 Published by Elsevier B.V. All rights reserved.