PORRSCON

New tools and approaches to control Porcine Reproductive and Respiratory Syndrome (PRRS) in the EU and Asia

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 Obiettivo del progetto (Objective)

'Porcine reproductive and respiratory syndrome virus (PRRSV) is the major cause of reproductive and respiratory problems in pigs worldwide. Controlling this disease is a top priority in pig producing countries. Due to mutations at a high frequency, new variants of the virus appear that are no longer effectively controlled by the commercial vaccines. In addition, highly virulent variants emerge, leading to high losses. With regard to animal welfare and agricultural economics, there is an urgent need to control PRRS. Furthermore, the abusive use of antibiotics to control PRRSV-associated respiratory problems may lead to resistance that may endanger public health. PoRRSCon is an initiative of 14 partners originating from Europe and Asia with strong expertises in virology and immunology. They are doing frontline research on PRRSV and/or vaccine development. Two of these partners are leading European pharmaceutical companies that will guide the consortium in the direction of exploitable results. By joining their strengths they have an ideal position to be successful in one of the most difficult challenges in pig health, controlling PRRS. To reach this final goal, the following objectives are forwarded:(i) characterize genetically and antigenically current PRRSV isolates in Europe and Asia, (ii) have a better understanding of the complex pathogenesis of PRRSV infections, immune response against PRRSV and immune modulation by PRRSV, (iii) define the genetic base of PRRSV virulence, (iv) identify PRRSV proteins and domains on these viral proteins that are involved in the induction of the immunity against PRRSV and in the immune modulation of PRRSV, (v) develop new generation, efficacious and safe marker vaccines that can be adapted to temporary changes and geographical differences and (vi) develop DIVA assays that allow to differentiate infected from vaccinated animals. At the end, it will be possible to set up a control strategy by combining marker vaccines with DIVA assays'

Introduzione (Teaser)

Porcine reproductive and respiratory syndrome virus (PRRSV) constitutes one of the most prevalent infectious diseases in pigs worldwide. Controlling the spread of the virus is crucial to reduce the incurred economic losses.

Descrizione progetto (Article)

PRRSV has considerable genetic variability with emergence of highly pathogenic strains causing extensive pig mortality. It causes reproductive and respiratory problems in pigs and is also undermining the pig's immunity, leading to extensive bacterial infections. Existing vaccines are unable to control all PRRSV strains and widespread use of antibiotics only exacerbates drug resistance incidence.

Seeking to address these issues, the EU funded http://www.porrscon.ugent.be/ (PORRSCON) (New tools and approaches to control porcine reproductive and respiratory syndrome (PRRS) in the EU and Asia), a collaboration between Europe and Asia set out to develop new tools and approaches to control PRRS. In this context they created a public virus bank that included European, Asian and American isolates encompassing both virus genotypes.

Partners sequenced and characterised a number of PRRSV strains with different genotypes and subtypes. For diagnosis, the majority of available PRRSV kits were validated using particular virus subtypes most common in Europe. However, these kits may not be as sensitive for detecting other virus subtypes, emphasising the need for continuously monitoring PRRSV genetic diversity and evaluating diagnostic tests. Ultimately, results revealed that a combination of techniques including serological analysis could prove to be more effective for PRRSV detection.

A currently available vaccine generated against subtype 1 was found to offer partial protection against the highly pathogenic PRRSV subtypes of Eastern Europe. Significant effort was devoted to the development of new vaccines capable of boosting PRRSV-specific humoral immunity and reducing virus load in piglets.

To further facilitate the design of novel vaccines, scientists performed virulence analysis and identified two implicated genes, which could be targeted to attenuate the virus. In addition, they investigated the pathogenesis of congenital infection and measures that could prevent infection of foetuses. To this end, they found one attenuated vaccine capable of protecting piglets against lethal challenge.

Overall, the activities of the PORRSCON project have alerted authorities about PRRSV transmission through international animal trade. The generated tools and vaccines are anticipated to control virus spread and minimise its detrimental consequences.