Caprine arthritis-encephalitis in goats and leukemia in cattle (cattle do not have CAE), two common infectious diseases of cattle and sheep, often cause economic losses for farmers, while dairy farmers and sheep farmers are often unaware. How to develop an unplugged, on-site rapid screening method to help popularize independent rapid testing technology for infectious diseases in cattle and sheep has become 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 also causes leukoencephalomyelitis in young goats. Caprine arthritis-encephalitis is mostly transmitted vertically from mother goats to young goats through milk and colostrum, and some is also transmitted horizontally to companions through contact between goats.

"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 method, no way to prevent it A threat to the health of cattle and sheep

Clinically, the symptoms of infected cattle and sheep vary greatly. In terms of arthritis, some cattle and sheep may develop severe lameness within several months or one to two years, while others only show intermittent lameness or joint stiffness, which can persist for years without worsening. In addition, the mammary gland cells of infected cows and ewes are infiltrated by monocytes, causing hardening of the udder and 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 even show few obvious clinical symptoms, it is not easy to detect. In addition, there is currently no drug treatment or vaccine for preventive injection. If one wants to prevent the spread of this disease, the first step is to strictly isolate newborn young goats so that they do not consume the colostrum and milk of infected mother goats, cutting off the route of transmission, and then gradually cull infected goats.

Overturning tradition Making testing technology faster and more precise

In the past, the main approach to preventing and detecting caprine arthritis-encephalitis virus was for testing units to arrange personnel to visit farms to help collect blood, bring it back to the laboratory, and then test it using the traditional enzyme-linked immunosorbent assay (ELISA), after which test reports were provided. The process of waiting for personnel and reports was lengthy (generally about 1 week), and often could not keep up with the need to quickly track and implement screening of young goats.

To this end, Professor Wang Pei-hua led a research team headed by Dr. Tu Po-an, with faculty and students joining forces in research, hoping to introduce a simpler, portable alternative solution, like rapid influenza screening, 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 dedicated to research and also serves at the Hsinchu Branch of the Council of Agriculture's Livestock Research Institute, said that from testing on goats to the planned application this year to the detection of bovine leukemia, the experimental team's previous testing for CAE disease in goats mainly used isothermal nucleic acid amplification to amplify CAEV virus sequences for detection. By directly detecting the CAEV virus nucleotide sequence to confirm whether goats carry CAE virus, and under rigorous review and verification, this technology can be applied not only in laboratory operations, but also directly and rapidly on livestock farms.

No need for expensive equipment, no need for electricity Helping reduce disease incidence

Through the efforts and continuous attempts of the research team, 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 for rapid screening on livestock farms.

During operation, it is only necessary to first collect blood from goats, perform simple DNA extraction on the obtained blood sample, then subject the sample DNA to be tested to isothermal amplification of viral nucleic acid, react the product with probes already placed on the test strip, carry out a color reaction through fluid capillary action, 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 preliminary screening and detection of animal diseases on site," Tu Po-an said with a smile.

This technology is not only easy to operate and easy to carry, but can also 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 and raise cattle and sheep not affected by CAE virus, and while reducing 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 reduce the disease risk of cattle and sheep, 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 the pig farming industry, which is relatively large in economic scale in Taiwan, China, helping more livestock farmers effectively reduce animal disease risk while creating higher benefits and output value.

Related information

For further details on the research and development results of this project, please contact Mr. He of the Agricultural Technology Research Institute, telephone: 03-5185049, email: [email protected]