Identification and cloning of a novel plasmid-encoded enterotoxin of enteroinvasive Escherichia coli and Shigella strains.

We have employed a molecular genetic approach to characterize the nature of enteroinvasive Escherichia coli (EIEC) enterotoxic activity, as previously observed in Ussing chambers (A. Fasano, B.A.

Heterogeneity of enteroaggregative Escherichia coli virulence demonstrated in volunteers.

Enteroaggregative Escherichia coli (EAggEC) are diarrheal pathogens defined by aggregative adherence to HEp-2 cells. In an effort to identify pathogenic EAggEC isolates, four groups of 5 volunteers were fed 1 of 4 different EAggEC strains, each at a dose of 10(10) cfu. Strain 042 caused diarrhea in 3 of 5 adults; 3 other EAggEC isolates (17-2, 34b, and JM221) failed to elicit diarrhea.

Plasmodium falciparum: inhibition of sporogonic development in Anopheles stephensi by gram-negative bacteria.

We investigated the effects of bacteria on Plasmodium falciparum sporogonic development in Anopheles stephensi. Four gram-negative (Escherichia coli H243, E. coli HB101, Pseudomonas aeruginosa, and Ewingella americana) and two gram-positive (Staphylococcus aureus and Staphylococcus epidermidis) bacterial strains were used in the study.

Comparison of the safety and immunogenicity of delta aroC delta aroD and delta cya delta crp Salmonella typhi strains in adult volunteers.

Three attenuated Salmonella typhi strains have been constructed by introducing deletions in aroC and aroD or deletions in cya and crp into one of two wild-type parent strains, Ty2 or ISP1820. These mutant strains were designated CVD 906 (ISP1820 delta aroC delta aroD), CVD 908 (Ty2 delta aroC delta aroD), and chi 3927 (Ty2 delta cya delta crp). Two studies were conducted with 36 healthy adult inpatient volunteers to determine in a double-blind fashion the safety and immunogenicity of approximately 5 x 10(4) and 5 x 10(5) CFU of each of these three vaccine candidates given as a single dose.

Clinical acceptability and immunogenicity of CVD 908 Salmonella typhi vaccine strain.

An attenuated Salmonella typhi strain has been sought as an improved oral typhoid vaccine and as a carrier of protective antigens of other pathogens to make hybrid vaccines. Ideally, such a strain would be safe and induce protective immune responses after a single oral dose. CVD 908 is a mutant of S.