Streptococcus pneumoniae peptides enhance vaccine efficacy.

2003 AUG 20 - (NewsRx.com & NewsRx.net) -- by Maria G. Essig, MS, ELS, senior medical writer - Foreign and self-derived peptides increased the protective ability of vaccines prepared with whole parent proteins of Streptococcus pneumoniae, according to a report in the Journal of Immunology.

"We induced T cell help for vaccination against Streptococcus pneumoniae (Pn) using self and foreign peptides and their source proteins conjugated to the capsular polysaccharide (CPS) of type 4 Pn; the carriers were self-heat shock protein 60 (HSP60) and tetanus toxoid (TT)," said Hila Amir-Kroll and collaborators at the Weizmann Institute of Science in Israel.

The investigators measured the production of IgG antibodies specific for the capsular polysaccharide and the carriers in vaccinated mice. They also determined whether vaccination protected the mice against challenge with a normally lethal intraperitoneal dose (LD[subscript]50 x 10[superscript]3-10[superscript]6) of S. pneumoniae.

"We now report that vaccination protects old and young mice from bacterial challenge; however, there were significant differences in vaccine efficacy based on the carrier," reported Amir-Kroll and associates.

The self-derived HSP60 peptide p458m provided greater protection against challenge than did the whole HSP60 protein. In fact, p458m protected mice against challenge as well as the tetanus toxoid. One inoculation with p458m or the tetanus toxoid was more protective than was ...