Nowadays, the possibility of reducing or administering vaccines simultaneously clearly means both an improvement in animal welfare and in labor efficiency. Due to this tendency, the possibility of mixing UNISTRAIN® PRRS with other vaccines led HIPRA to assess the viability of PRRSv in combination with an inactivated Swine Influenza vaccine (GRIPORK®).
Nowadays, many vaccination protocols have to be implemented in sows during the gestation and lactation periods. The possibility of simultaneous vaccine administration protocols can potentially improve both animal welfare and the efficiency of farm employees.
Many PRRSv vaccine combinations has been evaluated, but only some of them have shown their safety and efficacy, such as the combination of UNISTRAIN® PRRS with PPV and SE vaccine ERYSENG® PARVO. As a first step in this combination strategy, an in vitro trial was carried out to asses UNISTRAIN® PRRSv viability, when reconstituted in an inactivated Swine Influenza vaccine- GRIPORK® and also in a commercial solvent.
One 50-dose freeze dried tablet of UNISTRAIN® PRRS (strain VP-046 BIS.) was reconstituted in a 50 dose bottle (100 ml) of s GRIPORK®. Another 50-dose freeze dried tablet of UNISTRAIN® PRRS was reconstituted in 100 ml of an aqueous commercial solvent. Just after reconstitution and at 1, 2, 3 and 4 hours post reconstitution at 25° C, virus titers were measure by cytopathic effect in the CLON 8 cell line.
The following table includes PRRSv titers at a specific time after reconstitution with both GRIPORK® and the commercial solvent:
The PRRSv vaccine, when mixed with GRIPORK®, maintained its in vitro viability for four hours after reconstitution. The virus titer values over the whole study (4 hours) were equivalent or higher than the Minimum Effective Concentration (MEC) of the product (103.5 – 105.5 CCID50). The same results, namely that the MEC remained constant, were obtained when UNISTRAIN® PRRS was diluted in the commercial solvent.
These In vitro results confirm that the inactivated swine influenza virus vaccine- GRIPORK® does not interfere with PRRSv- UNISTRAIN® PRRS-viability. Moreover, PRRSv titers keep their MEC for 4 hours after reconstitution. Subject to further in vivo studies to ensure safety and the immunogenic response after vaccine mixing, UNISTRAIN® PRRS and GRIPORK® could be considered as a potential vaccine combination on commercial farms.