Researchers test promising neosporosis vaccine for cattle

Beltsville, Md.

-- A new vaccine against neosporosis in cattle looks promising, according to researchers conducting efficacy testing at USDA's Agricultural Research Service (ARS).

Photo: Paul Tearle/Getty Images

Neosporosis, caused by the parasite

Neospora caninum

, affects cattle worldwide. Infected animals typically abort their calves and develop other debilitating complications, costing producers millions of dollars each year.

Animal scientist Wenbin Tuo and microbiologist Mark Jenkins at the ARS Animal Parasitic Diseases Laboratory collaborated with ARS Molecular Plant Pathology Laboratory molecular biologist Yan Zhao and National Institutes of Health researcher Daming Zhu to test the neosporosis vaccine in a mouse model.

The team created the vaccine using the parasite's own proteins. One of these proteins, called Neospora caninum cyclophilin (NcCyP), regulates the response of the host immune system that limits the survival of the parasite in the host after infection. The other protein, called NcSRS2, helps the parasite attach to and invade host cells, ARS explains.

Ultimately, three different vaccine cocktails containing these proteins were tested. One group of mice received a formulation of NcCyP. A second group received a formulation of NcSRS2. A third group was immunized with a mix of both proteins. After vaccination, the mice were inoculated with the parasite.

The researchers found mice that received the vaccine formulated with NcCyP alone exhibited the highest levels of protection against the disease. On average, only 13 percent of the mice in this group had detectable levels of N. caninum in brain tissue following infection. In contrast, more than 80 percent of the non-vaccinated mice were infected after challenge.

The scientists found that the serum antibody levels against the protein correlated well with the levels of protection. The researchers also observed that the vaccine containing both NcCyP and NcSRS2 was no more effective than the vaccine that just contained NcCyP.

More work is needed to evaluate the efficacy of these proteins in protecting cattle against the disease, officials say.