Safety and immune responses after intradermal application of Porcilis PRRS in either the neck or the perianal region

Abstract

The objective of the present study was to assess safety and immune responses in gilts after intradermal application of Porcilis® PRRS in two different application sites under field conditions. Forty-four gilts were allocated to one of three groups: Gilts of group 1 (n = 10) served as non-vaccinated controls, gilts of group 2 (n = 17) were vaccinated intradermally in the neck and gilts of group 3 (n = 17) received an intradermal vaccination in the perianal region. Clinical observations, local injection site reactions and histopathologic examination of the injection site were used for safety assessments. Frequency and degree of clinical signs were not significantly different between all three groups. Minor local reactions for both vaccination groups were observed; however, at 6, 7, 8, 9 and 15 days post-vaccination (dpv), the mean injection site reaction score was significantly lower in pigs vaccinated in the perianal region. In histopathologic examination, an extended inflammatory dimension was observed more frequently in pigs vaccinated in the neck. Blood samples were analyzed to quantify the post-vaccination humoral (ELISA and virus neutralization test) and cellular (IFN-γ ELISPOT) immune responses. PRRSV-specific antibodies were present in the serum of all vaccinated animals from 14 dpv onwards, whereas all control pigs remained negative throughout the study. Neutralizing antibody titers were significantly higher in pigs vaccinated in the perianal region at 28 dpv. At 14, 21 and 28 dpv, PRRSV-specific IFN-γ secreting cells were significantly increased in both vaccination groups compared to non-vaccinated gilts. Analysis of mean numbers of PRRSV-specific IFN-γ secreting cells did not result in statistically significant differences between both vaccination groups. The results of this study indicate that the perianal region is a safe alternative application site for intradermal vaccination of gilts with Porcilis PRRS. Furthermore, the intradermal application of Porcilis PRRS induced humoral and cellular immune responses independent of the administration site.

Dynamics and Differences in Systemic and Local Immune Responses After Vaccination With Inactivated and Live Commercial Vaccines and Subsequent Subclinical Infection With PRRS Virus

“…Despite the fact that many studies focused on PRRS immunoprophylaxis have already been published and many procedures are implemented in the agricultural industry, a universal model does not yet exist (46)(47)(48)(49)(50)(51)(52)(53)(54)(55)(56)(57)(58)(59)(60). The use of live attenuated vaccines is generally preferred as was also confirmed in our field study (61).…”

“…This effect is attributed to the use of strong adjuvants in inactivated types of vaccines. In the test of IFN-γ production and detection with ELISpot, which is very often used to identify CMI both in experimental studies (5,37), and in the field (49,50), we have shown an increase in both blood and cells acquired by lavage, but the individual variability among the animals was too high and, consequently, there were no differences found between the groups under study. We detected also IFN-γ producing lymphocytes after PRRS antigen stimulation in all immunized groups 7 days after infection.…”

“…The partial results were provided by each of the three methods used and a comprehensive picture could be obtained by compiling this information. Therefore, it was not possible to use only data of IFN-γ production in ELISpot, although it is currently the most commonly used method for CMI (5,29,37,38,49,50). A positive cell-mediated response after lymphocyte stimulation with specific antigen in vitro (in lymphocyte transformation test) was observed in MLV groups and especially in the B4 group as a non-specific basal stimulation occurred from 21 days post-vaccination in B3 group.…”

“…The dynamics of virus shedding after vaccination and infection is often used for monitoring vaccine efficacy (30,40,49). The decrease in virus secretion was observed 14 days after MLV immunization and disappearance in 28 days (42).…”

Welfare Benefits of Intradermal Vaccination of Piglets

“…This reaction was described as a spot of 0.2–0.5 cm diameter detected through palpation at the site of injection. In a recent study, minor local reactions were also observed in sows after intradermal vaccination [ 38 ]. Contrary to IDAL vaccination, the deposition of the vaccine in the IM group is into the muscle and any local reaction may not be readily visible without undergoing necropsies.…”