Efficacy of Needle-Less Intradermal Vaccination against Porcine Epidemic Diarrhea Virus

Abstract

To prevent diarrhea in suckling piglets infected by porcine epidemic diarrhea virus (PEDV), porcine epidemic diarrhea (PED) vaccines are administered mainly through intramuscular (IM) or oral routes. We found that growing pigs vaccinated with an inactivated PEDV vaccine via the intradermal (ID) route had higher neutralizing antibody titers and cytokine (IFN-γ, IL-4, and IL-10) levels than non-vaccinated pigs. In addition, suckling piglets acquired lactogenic immunity from pregnant sows inoculated with an ID PED vaccine. We evaluated the efficacy of vaccination via this route, along with subsequent protection against virulent PEDV. At six days post-challenge, the survival rate of suckling piglets exposed to virulent PEDV was 70% for the ID group and 0% for the mock group (no vaccine). At necropsy, villi length in the duodenum and ileum of piglets with lactogenic immunity provided by ID-vaccinated sows proved to be significant (p < 0.05) when compared with those in piglets from mock group sows. Thus, vaccination using an inactivated PED vaccine via the ID route provides partial protection against infection by virulent PEDV.

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

“…In a few studies, minipigs were used as they are regarded as a suitable model when it comes to vaccination through the skin [ 83 ]. It is noted that almost half of the identified papers (n = 57), do not name the pig breed, often referring to it only as commercial breed [ 49 , 51 , 76 , 108 , 109 , 110 , 111 , 112 , 113 , 114 , 115 , 116 , 117 , 118 , 119 , 120 , 121 , 122 , 123 , 124 , 125 , 126 , 127 , 128 , 129 , 130 , 131 , 132 , 133 , 134 , 135 , 136 , 137 , 138 , 139 , 140 , 141 , 142 , 143 , 144 , 145 , 146 , 147 , 148 , 149 , 150 , 151 , 152 , 153 ,…”

“…Over 60% of identified papers using skin-based vaccination in pigs included adjuvants; the majority mixed or co-inoculated with the vaccine [ 51 , 76 , 88 , 108 , 110 , 112 , 113 , 115 , 117 , 118 , 119 , 120 , 121 , 122 , 123 , 124 , 125 , 129 , 131 , 132 , 133 , 134 , 137 , 138 , 139 , 140 , 141 , 142 , 143 , 144 , 146 , 151 , 153 , 154 , 156 , 158 , 159 , 160 , 161 , 168 , 179 , 180 , 182 , 186 , 187 , 188 , 196 , 198 , 199 , 201 , 202 , 203 , <...…”

“…They are particularly used for livestock vaccines given their low cost, ease of preparation and use, and efficacy [ 250 , 251 , 252 , 253 ]. Special attention needs to be taken when choosing the type of emulsion, as the benefit of protection against virus challenge must be greater than skin-based reactogenicity, as seen for a PEDV vaccine [ 121 ] but not for other vaccines [ 132 , 253 ]. Some emulsion-based adjuvants have also shown to be safe for skin administration, inducing a strong response mediated by skin DCs [ 125 , 199 , 210 ].…”

“…Within the papers analysed in this review, 14 studies have documented vaccine-induced mucosal immunity. These mucosal samples include saliva [ 49 ], bronchoalveolar lavage (BAL) [ 51 , 115 , 182 ], nasal mucosa [ 50 , 118 , 202 , 204 , 226 , 229 ], colostrum [ 121 ], gut [ 122 , 206 , 208 ] and vaginal mucosa [ 202 , 204 ].…”

“…Specifically, a positive correlation between protection and amount of nasal IgA was observed, although to a lesser extend than that observed for serum IgG [ 50 ]. Furthermore, inactivated and viral vector vaccines targeting M. hyopneumoniae , Classical Swine Fever virus and Porcine Epidemic Diarrhea Virus have been able to elicit mucosal antibodies in pigs after intradermal immunisation by needles or jet injector [ 49 , 51 , 121 ]. Mucosal antibodies were proposed to improve survival of vaccinated sows [ 49 ] and partial protection of their piglets through colostrum [ 121 ].…”