Award for Young Members by Italian Society of Parasitology to participate in the XXX Congress of the Italian Society of Parasitology (SOIPA) “Environmental changes and parasites”

Toward the development of serological markers of human exposure to Aedes mosquitoes: analysis of Aedes albopictus salivary antigens in a murine model. S. BUEZO MONTERO1, P. GABRIELI2, F. SEVERINI3, L. PICCI3, M. DI LUCA3, F. FORNERIS2, L. FACCHINELLI4, M. PONZI3, F. LOMBARDO1, B. ARCÀ1 1. Department of Publich Health and Infectious Diseases, Division of Parasitology, Sapienza University, Rome, Italy. 2. Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, Italy. 3. Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy. 4. Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK. Introduction. The rapid spread in the European continent of Aedes albopictus and its involvement in recent outbreaks of chikungunya and dengue in Italy, France and Croatia highlighted the need to improve surveillance and control of Ae. albopictus and other Aedes invasive species. We previously showed that the IgG response to the Anopheles gambiae salivary protein gSG6 is a reliable marker to evaluate human exposure to malaria vectors (Rizzo et al., 2011 PloS ONE 6:e17980). Exploiting Aedes-specific salivary proteins previously identified by comparative analyses (Ribeiro et al., 2010 Insect Biochem Mol Biol 40:767-84) we plan to develop similar serological tools to assess human exposure to Aedes mosquitoes. Materials and Methods. Three groups of 4 naïve BALB/c mice were exposed to bites of either Ae. albopictus or Ae. aegypti or An. coluzzii. Serum samples were collected before exposure, after the 2nd and the 4th/last exposure and then 1, 2, 3, 5 months later. The IgG response to (i) salivary gland extracts (SGE), (ii) the 34 kDa salivary protein from Ae. albopictus (alb34k) and Ae. aegypti (ae34k) and (iii) Aedes-specific salivary peptides was measured by ELISA. Moreover, the response was analyzed in a volunteer who regularly fed an Ae. albopictus colony for ~3 months (L13) and then after 2 years of non-exposure (L16). Results and conclusions. The immunization protocol was effective, especially in the case of Ae. albopictus and Ae. aegypti, as indicated by the IgG response to SGE. Two of the four Ae. albopictus-exposed mice had IgG antibodies against alb34k but no one responded to ae34k. All Ae. aegypti-exposed mice exhibited high levels of anti-ae34k IgG but no antibodies to alb34k, confirming that despite the high identity (63%) of the two orthologous proteins there was no significant cross-reactivity in mice. No response to alb34k or ae34k was observed in mice exposed to An. coluzzii. Similar results were found in the single human hyperimmune serum (L13) analyzed, with high levels of anti-alb34k IgG and a negligible response to ae34k. Moreover, a significant drop of the anti-alb34k IgG levels was observed after two years of non-exposure (L16) to Ae. albopictus. Further validation, making use of a larger and proper set of human sera from individuals naturally exposed to Ae. albopictus, is certainly needed. Nevertheless, the study reported here identified some promising candidates for the development of immunoassays suitable for the assessment of human exposure to Aedes vectors of public health importance as Ae. albopictus and Ae. aegypti