Intradermal DNA vaccination in ear pinnae is an efficient route to protect cats against rabies virusEmiliano Tesoro-Cruz1, 2, Rafael Calderón-Rodríguez1, 2, Rafael Hernández-González2, Francisco Blanco-Favéla1 and Alvaro Aguilar-Setién1
1 Unidad de Investigación Médica de Alta Especialidad en Inmunología, IMSS, México DF
2 Departamento de Investigación Experimental y Bioterio del Instituto Nacional de Ciencias Médicas y Nutrición "Salvador Zubirán" (INCMNSZ), México DF
(Received 8 February 2007; accepted 11 October 2007; published online 16 January 2008)
Abstract - A DNA vaccine against rabies (pGQH) was administrated to cats in order to examine different administration routes. Four groups of three cats each were inoculated with pGQH as follows: group A, intramuscularly (IM), 100 g; group B, intranasally (IN), 100 g; group C, intradermally into ear pinnae (ID-EP), 100 g, and group D, IM, 200 L of phosphate buffer solution (PBS) alone (control group). Blood was drawn on days 0, 30, 60, 90, 120, 150, and 180. Groups A, B, and C received a booster on day 30. At day 200 all animals were challenged. A passive transfer of cat sera, as well as a viral challenge, was performed in mice. The results displayed that neutralizing antibody titers were higher in cats of group C (ID-EP) showing high early titers (> 2 IU) and the highest titer was on day 120 (> 14 IU). In group B (IN), two out of three cats seroconverted on day 30 (> 0.5 IU), the third cat seroconverted until day 60 (> 0.5 IU). In contrast, the lowest levels of neutralizing antibodies were detected in group A (IM). The control group showed no anti-rabies antibodies. Groups A (IM) and D (control) succumbed after lethal challenge. All animals from the ID-EP group (C) survived, only one individual from the IN (B) group died. Mice that received cat sera from ID-EP, IM, and IN groups survived and were protected (30/30 survivors). Mice groups that received pre-immunization sera from cats were not protected (0/30 survivors). This study demonstrates that pGQH immunization was successful when it was administrated ID-EP, and acceptable through the IN route. The IM route, however, was not effective in cats. For vaccination, the IN route seems attractive due to its accessibility for application, but it seems to activate seroconversion slowly. The best route to promote anti-rabies antibody titers was the ID-EP route. This practical and efficient route should be further studied.
Key words: rabies / DNA vaccine / intradermal into ear pinna / intranasal / cats
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© INRA, EDP Sciences 2008