Porcine reproductive and respiratory syndrome virus (PRRSV) infects domestic pigs. It belongs to the family Arteriviridae, genus Arterivirus and there are two genotypes – 1 (European) and 2 (North American). Highly pathogenic strains of the North American genotype emerged in China in the late 2000s, which are more virulent than the other strains. PRRSV is enveloped and has a capsid that encases a single stranded RNA genome.
PRRSV causes porcine reproductive and respiratory syndrome which is highly infectious – as little as 10 virons are needed to infect an animal although it is not highly contagious. The clinical signs vary depending on the age of animal infected; breeding age pigs are affected more commonly with the reproductive syndrome, whilst piglets and young pigs are affected by the respiratory syndrome.
- Decrease in conception
- Increase in premature birthing, late term abortions, stillborn or weak piglets and mummified foetuses.
- High preweaning mortality
- Perhaps respiratory distress or vomiting
- Blue colouring due to decrease blood flow (cyanosis) of the ears, abdomen and vulva
- Difficulty breathing
- Stunted growth due to systemic disease
- Increased post weaning mortality
PRRSV spreads through direct contact, and may also be transmitted though artificial objects such as vehicles. Artificial insemination also transmits the virus as it is present in semen as well as in nasal secretions, urine, mammary secretions and faeces. Pregnant sows may pass the virus on and deliver persistently infected piglets.
PRRS is found in most areas of the world where pigs are raised. Although genotypes 1 and 2 predominate in Europe and North America, respectively, both have spread to countries such as China, Japan, Vietnam, the Philippines, Malaysia, and Korea among other countries in Asia.
Impact for Society – what are we doing?
PRRS is now the most economically important disease for the global pig industry, with losses estimated to exceed $664 million annually in the USA alone. The rapid evolution of PRRS prevents efficient control and vaccination.
By understanding the protective immune responses to PRRSV, the Institute will be able to design safer and more effective vaccines. Working with global animal health businesses to develop improved vaccines will contribute towards creating a more efficient and sustainable pig industry both in the UK and overseas.
*Image courtesy of Dr Javier Salguero, University of Surrey