Caprine arthritis-encephalitis in goats and bovine leukemia in cattle (cattle do not have CAE) are two common infectious diseases of cattle and sheep that often cause economic losses for farmers, yet dairy and sheep farmers are often unaware of them. How to develop a battery-free, on-site rapid screening method to help popularize self-service rapid testing technology for infectious diseases in cattle and sheep became the shared goal of the faculty-student team led by Professor Wang Pei-hua of the Department of Animal Science and Technology at National Taiwan University.

Among these, caprine arthritis-encephalitis (CAE) is caused by a chronic virus that causes adult dairy or meat goats to suffer from chronic arthritis and mastitis that do not respond to treatment, and can also cause kids to develop leukoencephalomyelitis. Caprine arthritis-encephalitis is mostly transmitted through milk and colostrum, passed vertically from mother goats to their kids, and some cases are also transmitted horizontally between goats through contact with one another.

"This virus affects the lactation and health of cattle and sheep, and the most direct result is invisible economic losses for livestock farmers," pointed out Professor Wang Pei-hua of the Department of Animal Science and Technology at National Taiwan University.

No Treatment, No Prevention A Threat to Cattle and Sheep Health

Clinically, the symptoms of infected cattle and sheep vary greatly. In terms of arthritis, some cattle and sheep may develop severe lameness within a few months or one to two years, while others show only intermittent lameness or joint stiffness that can persist for years without worsening. In addition, the mammary gland cells of infected cows and ewes are infiltrated by mononuclear cells, causing the udder to become firm and leading to agalactia, making this one of the major diseases that deeply troubles the livestock industry.

Because the interval between infection and the appearance of symptoms in cattle and sheep is relatively long, and some animals may even show no obvious clinical symptoms at all, the disease is difficult to detect. In addition, since there is currently no drug treatment or vaccine for prevention, the first step in preventing the spread of this disease is to strictly isolate newborn kids so they do not consume the colostrum and milk of infected mother goats, cutting off the route of transmission, and then gradually cull the infected goats.

Overturning Tradition Making Testing Technology Faster and More Accurate

In the past, the approach to preventing and detecting caprine arthritis-encephalitis virus mainly involved testing units arranging personnel to visit farms to help collect blood samples, which were brought back to the laboratory and tested using the traditional enzyme-linked immunosorbent assay (ELISA), after which test reports were provided. The process of waiting for personnel and for reports to be produced was lengthy (generally requiring about 1 week), and often could not keep up with the need to rapidly track and implement screening of kids.

To address this, Professor Wang Pei-hua led a research team headed by Dr. Tu Po-an, with faculty and students joining forces to conduct research, hoping to introduce a simpler, portable alternative solution, much like a rapid influenza test, so that in the future livestock farmers can also directly perform rapid CAE testing of goats on site.

Associate Researcher Tu Po-an, who is devoted to the research and also serves at the Hsinchu Branch of the Council of Agriculture's Livestock Research Institute, stated that from testing on goats to the planned application to bovine leukemia testing this year, the experimental team previously used isothermal nucleic acid amplification to amplify CAEV viral sequences for detection of CAE disease in goats. By directly detecting the CAEV viral nucleotide sequence to confirm whether a goat carries the CAE virus, and under rigorous review and validation, this technology can be applied not only in laboratory operations but can even be operated directly and rapidly on livestock farms.

No Need for Expensive Equipment, No Need for Electricity Helping Reduce Disease Incidence

Through the research team's efforts and continuous experimentation, a set of goat blood sample processing procedures was established, and the isothermal nucleic acid amplification fluorescent primers and detection probe design for caprine arthritis-encephalitis virus were completed, allowing more people to use this caprine arthritis-encephalitis virus rapid testing kit to conduct rapid screening on livestock farms.

To operate it, one only needs to first collect blood from the goat, perform a simple DNA extraction on the obtained blood sample, then subject the sample DNA to be tested to isothermal amplification of the viral nucleic acid, and then react the product with the probes already placed on the test strip, using capillary flow to produce a color reaction, and finally determine the result with the naked eye; if a reaction line appears, it is judged positive.

"The entire testing process can be completed within 1.5 hours, without the need for expensive instruments, and with almost no need for plug-in equipment, making it very suitable for on-site preliminary screening and detection of animal diseases," Tu Po-an said with a smile.

This technology is not only easy to operate and easy to carry, but can be operated directly whether in the laboratory or on livestock farms, enabling rapid diagnosis. It can help the industry year by year reduce cattle and sheep carrying the undesirable CAE virus, help farmers effectively identify and isolate for rearing cattle and sheep that have not been affected by the CAE virus, and while lowering the disease incidence rate, also improve the economic losses of the goat industry. This technology for rapid on-site testing of CAE in goats has already obtained patents in both Taiwan, China and the United States, and manufacturers have already expressed interest in technology transfer.

In addition to effectively helping cattle and sheep reduce disease risk, Professor Wang Pei-hua also hopes that in the future this innovative technology can be widely applied to more livestock-related disease prevention and screening procedures, such as in Taiwan, China's relatively large-scale pig farming industry, helping more livestock farmers effectively reduce animal disease risk while creating higher benefits and output value.

Related Information

To learn more about the details of this project's research and development results, please contact Mr. He of the Agricultural Technology Research Institute, telephone: 03-5185049, email: [email protected]