PCV2 Impairs Danger Recognition, Says Top Expert

13 December 2011, at 5:02pm

UK - Two leading experts on PCV2 provided vets with an update on the virus at the Pig Veterinary Society's autumn meeting.

Dr Kenneth McCullough, Head of Research at Switzerland’s Institute of Virology and Immunoprophylaxis, talked about the impact of PCV2 on the immune system. Thais Vila, Technical Director for EMEA for swine products at Merial Animal Health, discussed the way that the disease manifests itself, and how herd management and vaccination can help to combat it.

Dr McCullough explained how PCV2 affects the porcine immune system and provided an insight into its interaction with the dendritic cells. He said these cells are critical because they trigger danger recognition, and thus help to provide the pig with immunity to disease. While the double-stranded DNA in PCV2 reduced the levels of danger recognition in the cells, the single-stranded DNA in the virus actually helped to induce this recognition.

He endorsed the early protection of pigs through vaccination, while emphasising the important role of herd management and nutrition.

Ms Vila said: "In recent years, the symptoms of PCV2 have become less obvious, and may even be sub-clinical. Nowadays, the symptoms may occur later in the pig's life. The clinical signs can be similar to other viral infections and may depend on co-infections. Symptoms include digestive and respiratory disorders.

"In sows, PCV2 affects reproduction including return to oestrus, increased abortions and stillbirths, and pre-weaning mortality. Naïve gilts are particularly at risk from the virus."

She explained that while vaccination has a critical role to play, there were a number of aspects of herd management which were also important. These included: colostrum intake, pig flow management, buildings, hygiene, feed, control of co-infections and genetics.

Her presentation included two case studies demonstrating the benefit of vaccination – one featuring piglet vaccination and one on sow vaccination. The first example featured a Spanish company that had focussed most of its attention on PRRS, but still had problems including poor performance, increased fattening mortality, and high incidence of pneumonia. As a result, it decided to vaccinate its piglets against PCV2. Two groups of pigs were compared – one before vaccination and one after.

Increased performance post-vaccination included a reduction in the number of days of feed, decreased mortality rates, and increased average daily weight gains and slaughter weights.

A German case study looked at the benefits of sow vaccination on reproduction across two cycles. This research showed that in sows vaccinated with Circovac®, the number of piglets increased by an average of 0.8. The number of weaned piglets increased by 0.7, which translates to an additional 1.6 pigs weaned per year per sow.

Dr Kenneth McCullough and Thais Vila

Further Reading

- Find out more information on Post-Weaning Multisystemic Wasting Syndrome (PMWS) caused by PCV2 by clicking here.

Further Reading

- Find out more information on PMWS by clicking here.