TRIALS are underway to assess the effectiveness of vaccines against porcine respiratory and reproductive syndrome virus (PRRSV) in pigs.

The Pirbright Institute has partnered with ECO Animal Health and The Vaccine Group to develop new PRRS vaccines to tackle the two PRRSV species (type-1 and type-2) responsible for one of the most most economically damaging diseases to the global pig industry.

Each year these species cost European pig farmers an estimated €1.5 billion a year and those in the US approximately $600 million.

In the first 18-month development project, Pirbright will test two vaccine candidates that use TVG’s vaccine technology to assess their effectiveness at tackling PRRSV in pigs.

The vaccines are created by inserting non-infectious conserved PRRSV genes supplied by Pirbright into a benign herpesvirus, which then stimulates the immune system when delivered into animals. Vaccines that use herpesviruses as their base have been shown to provoke particularly strong reactions from T cells, which are a vital part of the antiviral response.

Group Leader of PRRS Immunology at The Pirbright Institute, Professor Simon Graham, said: “This is an exciting project that takes a novel approach to addressing the urgent requirement for improved vaccines to combat the global spread of PRRSV.”

TVG founder and chief scientific officer, associate professor Dr Michael Jarvis said: “This is an exciting opportunity that brings together critical basic science and translational expertise towards addressing this major infectious disease in pigs. As PRRSV is a member of the Nidovirus group of viruses, a group that also contains SARS-CoV-2, what we learn from development of a PRRSV vaccine may also help inform our development of a vaccine against SARS-CoV-2.”

The second ECO funded project will see Pirbright develop a significantly improved killed vaccine over 18 months. The team will generate modified PRRSV strains and then inactivate them to create vaccine candidates. The strain modifications aim to prevent inappropriate antibody responses and enhance those that are thought to provide immunity against multiple strains of PRRSV.

This killed vaccine would offer an attractive alternative to the current generation of live vaccines, which are only partially effective against different strains and suffer from safety constraints owing to the potential for the live vaccine virus to revert back to an infectious form.

Professor Graham continued: “Creating a killed vaccine that can prevent the spread of multiple strains would provide flexibility in tackling outbreaks as well as an improved safety profile, both vital for effective control.”