Operation of a Research Unit for Surveillance of Infectious Diseases and Development of Vaccines

摘要

The following were the research activities conducted during the first year of the Cooperative Agreement DAMD17-98-8001: Project I: Cohorts of young soldiers serving in Israel Defense Force field units and naturally exposed to enteric pathogens have been maintained under intensive clinical and laboratory surveillance during the summer months of years 1997 and 1998. During this period, the incidence of shigellosis ranged between 24 and 67 cases per 1,000 per 3-6 summer months while the incidence of gastroenteritis associated with ETEC ranged between 57 and 63 per 1,000. Laboratory core: Study 1 - A collection of 392 Shigella and 137 ETEC strains isolated from subjects under surveillance during 1993-1997 were tested for antibiotic susceptibility. Study 2 - Nalidixic acid (NA) resistant S. sonnei strains isolated during an outbreak occurring in a pediatric population, were examined and compared to NA sensitive S. sonnei strains isolated in the same region. The molecular basis of the antimicrobial resistance to nalidixic acid is currently investigated in our lab. Study 3 - A PCR protocol for direct and rapid detection of shiga-like toxin genes in stool specimens was developed and used to identify SLT II in stools of children involved in an outbreak of diarrhea associated with E. coli 0157 and involving a case of hemolytic uremic dyndrome. Study 4 - Shigella LIPS antibodies, elicited by immunization with an experimental vaccine composed of S. sonnei or S. flexneri 2a O-specific polysaccharide conjugated to polysaccharide aeruginosa recombinant exoprotein, were quantified and characterized. Study 5 - The antibody-mediated killing of Shigella by phagocytes was tested using serum preparations containing different ratios of Shigella IgG1 and IgG2 antibodies. It was found that relatively high levels of IgG1 are crucial for efficient killing of the homologous Shigella organisms.