Vaccine targeting liver stage of malaria sporozoite elicits T cell response.

2003 JUN 11 - (NewsRx.com & NewsRx.net) -- by Maria G. Essig, MS, ELS, senior medical writer - A vaccine targeting the liver stage of the malaria sporozoite elicited CD4+ and CD8+ T cell responses, according to a report in the Journal of Immunological Methods.

"The liver stage of Plasmodium species now appears as a relevant target of immune effectors triggered by the so-called 'antisporozoite' vaccine," stated Armelle Hebert and colleagues at the Institut Pasteur in Paris. "Since the monitoring of immune responses at the systemic level may not faithfully reflect the local protective mechanisms, the aim of the present work was to set up a model to study the local intra-hepatic cellular responses and to compare these with the peripheral immune responses."

The investigators coated polystyrene microbeads with B and T cell peptide epitopes, which may mimic hepatic schizonts, and used them to immunize mice.

"Using the P. falciparum liver stage antigen-3 (LSA3) molecule, which can induce protection against a sporozoite challenge, our results show that 25-micrometer microbeads could easily access the liver parenchyma by intra-portal injection and were distributed evenly in the liver," reported Hebert and associates. "Also, LSA3-derived synthetic peptides coated onto microbeads initiated specific cell recruitment within six hours."

Strongest cell recruitment was accomplished with nonrepeat II peptide (NR2)-coated microbeads with an average leukocyte number of 79 per granuloma. Immune responses to the microbeads ...