Efficacy of Simultaneous Intradermal Vaccination of Swine against Porcine Circovirus 2, Porcine Reproductive and Respiratory Syndrome Virus, Mycoplasma hyopneumoniae and Lawsonia intracellularis

Abstract

The combined application of vaccines in swine offers many benefits, including reduced time and labour costs, and improved animal welfare, due to fewer injections and manipulations. This study investigated if simultaneous intradermal vaccinations against porcine circovirus 2, porcine reproductive and respiratory syndrome virus, Mycoplasma hyopneumoniae, and Lawsonia intracellularis, using a specialised needle-free applicator would confer comparable protection against experimental infection compared to the single vaccines. In all cases, the administration of the vaccines together was as efficacious as the administration of the vaccines alone, significantly reducing clinical signs associated with each of the four pathogens.

Skin-Based Vaccination: A Systematic Mapping Review of the Types of Vaccines and Methods Used and Immunity and Protection Elicited in Pigs

“…Contrary to what we observe in human vaccines, where adjuvants are generally reserved for subunit vaccines, many of the pig skin-based whole vaccines (live attenuated and inactivated) incorporate adjuvants. An example of this is the commercial vaccine Porcilis PRRSV consisting of a modified live virus (MLV) accompanied by dl-α-tocopherol acetate adjuvant mixed to form an emulsion [ 76 , 141 , 151 , 168 , 220 , 232 , 233 ].…”

“…Most publications evaluated PRRSV-specific antibodies (20 out of 23 papers) and T cells (15 out of 23 papers), whereas only one paper evaluated B cell responses. Out of the 20 studies that examined PRRSV-specific antibodies subsequent to skin-based immunisations, 12 reported achieving seroconversion after vaccination [ 76 , 134 , 135 , 139 , 141 , 151 , 155 , 157 , 220 , 225 , 226 , 233 ]. Seroconversion is defined as sample to positive (S/P) ratios above a 0.4 threshold.…”

“…Strong antibody responses, especially after challenge, were induced in a number of studies, for example, after three DNA immunisations [ 66 ] or subsequent to two adenoviral vector-based vaccine immunisations [ 231 ]. Compared with placebo, strong humoral responses induced by skin-based immunisation led to better protection after homologous, heterologous virus strain challenge or natural infection, shown as a decrease in clinical signs, lung lesions, viral shedding or viremia [ 76 , 112 , 134 , 135 , 139 , 157 , 220 ]. However, increased antibodies do not always correlate with protection, as observed by partial, limited or no efficacy of a subunit [ 123 ] or an inactivated vaccine [ 227 ] after challenge despite an increase in specific-antibodies.…”

“…Protection, however, is not necessarily only linked to antibodies, as cellular immune responses to PRRSV play an important role as well [ 76 , 112 , 135 , 139 , 141 , 157 ]. Seroconversion and efficacy with no significant differences in protection against challenge have been observed between the single vaccines and multivalent vaccines, the latter of which can contain PCV2, M. Hyopneumoniae and L. intracellularis [ 220 ].…”

“…The general systemic side effects of vaccination, including fever, weight loss and fatigue, were only mild or absent in the pigs vaccinated using the skin route [ 110 , 113 , 123 , 131 , 132 , 134 , 135 , 138 , 140 , 151 , 153 , 157 , 158 , 160 , 179 , 188 , 203 , 221 , 222 , 227 , 228 , 233 , 239 ]. In addition, co-administration of multiple vaccines into the skin has shown the same safety profile as individual vaccines for PCV2, PRRSV, M. hyopneumonia and L. intracellularis [ 153 , 220 ], which is not only convenient for the farmer but can also reduce the stress of handling and potential pain to the animals. Special attention is given to the safety of newly developed vaccines for skin administration.…”