A natural vaccine candidate strain against cholera

E1 Tor Vibrio cholerae (EVC) strains may be classified into two kinds-epidemigenic (EEVC) strains and non-epidemigenic (NEEVC) strains-based on a phage-biotyping system. A large number of EEVC strains have been screened for toxigenic and putative colonization attributes. One such naturally occurring strains (designated IEM101) has been found which is devoid of genes encoding cholera toxin (CT), accessory cholera enterotoxin (ACE), zonula occludens toxin (ZOT), but possesses RS1 sequences and toxin-coregulated pilus A gene (icpA) although icpA is poorly expressed. It expresses type B pili but does not possess type C pili. It is an E1 Tor Ogawa strain and does not cause fluid accumulation in rabbit ilcal loop tests. Active immunization of rabbits with strain IEM101 elicited good protection against challenge with virulent strains of V. cholerae O1. Oral administration caused no side effects in 15 human volunteers, colonized the gut for four to ten days and elicited good immune responses.     

Isolation of Enterobacteriaceae bacteriophage particles catalysing cell wall lipopolysaccharide degradation

Using pairs of smooth and rough forms of Enterobacteriaceae, six smooth-specific bacteriophages were isolated from sewage and another was obtained from Dr Hedda Milch, Budapest. Upon incubation of the individual extracted (smooth) host cell wall lipopolysaccharides with the homologous purified viruses, liberation of reducing groups (i.e. of about di- to nonasaccharides) was observed in four cases, indicating the action of glycanases - but no liberation of acetic acid, indicating the absence of esterase activity. Under the electron microscope, all phages were seen to exhibit Bradley group B or C morphology and to carry tail spikes.