Abstract: The possibility that antibody responses in serum, saliva, or breast milk samples to oral vaccines or enteric infections may reflect the intestinal immune response was evaluated in Bangladeshi volunteers orally immunized with a cholera B subunit-whole-cell vaccine (B + WCV) and in patients convalescing from enterotoxin-induced diarrheal disease. Two peroral doses of B + WCV induced antitoxin and antibacterial antibody responses in the intestinal fluids of 76 and 92%, respectively, of the volunteers and in serum samples in 90 and 69% of those tested. These responses were comparable to those obtained after cholera or enterotoxigenic Escherichia coli disease. Whereas immunoglobulin A (IgA) antitoxin titer increases in saliva (44%) and breast milk (29%) specimens after vaccination were less frequent than in intestinal fluid (76%), antitoxin responses in saliva and breast milk occurred in 80 to 90% of the patients after disease. Also, antilipopolysaccharide (anti-LPS) titer increases in extraintestinal body fluids were found more frequently after disease than after vaccination. A comparison of the frequency and magnitude of antibody response in different body fluids with those in intestinal lavage fluid revealed no extraintestinal antibody that directly reflected the intestinal immunity. However, comparison of vibriocidal and IgG antitoxin antibodies in serum specimens with antitoxin and anti-LPS IgA responses in intestinal fluids after the vaccination of volunteers showed a sensitivity of 70 to 90% and a predictive accuracy of about 80% for the serum analyses reflecting the intestinal immune responses. Furthermore, antitoxin and anti-LPS antibody responses in saliva and breast milk samples seemed to be useful proxy indicators of a gut mucosal response of these antibodies after enterotoxin-induced diarrheal disease showing sensitivity vales of 70 to 90% and predictive accuracy vales of 70 to 100%.

Abstract: Growing turkeys were partly protected against fowl cholera 4 days after vaccination with the live Clemson University (CU) strain of Pasteurella multocida administered in drinking water, and they were highly protected from 1 to 4 weeks after vaccination. The commercially available lyophilized vaccine and the freshly cultured vaccine of the CU strain did not differ in the level of immunity induced. Immunity was relatively high in turkeys vaccinated with 1:2 and 1:4 dilutions of the recommended dosage (4 X 10(8) P. multocida) but was significantly (P less than 0.05) lower in turkeys vaccinated with a 1:8 dilution of the recommended dosage. Immunity continued for 13 weeks after the last vaccination in turkeys vaccinated twice 3 weeks apart, but it persisted for only 8 weeks in those vaccinated only once.

Abstract: At this time it is possible with appropriate microbiological tests to identify a disease-causing agent in 60-85% of cases of pediatric diarrhea reaching health facilities in less developed nations. As the agents became known their epidemiology was studied to determine their relative importance the ages and geographical areas affected and the seasons when they occur. This was accompanied by research on pathogenesis which is basic to vaccine development. The result is that during the past few years extraordinary progress has been made in the development of new vaccines against many of the most important agents that cause diarrheal disease dysentery and enteric fevers. The present status of development of some of the new vaccines against enteric infections is reviewed. Investigators throughout the world have taken diverse approaches to the development of vaccines against rotavirus diarrhea but the approach that has rapidly yielded promising results involves the use of animal roatviruses as vaccines in humans. 2 animal rotavirus vaccines candidates are being extensively evaluated in human trials under the auspices of the World Health Organization (WHO). Strain RIT4237 a virus of calf origin has caused no notable adverse reactions in hundreds of young children vaccinated in the Gambia Finland Peru Rwanda and the US. Scientists in the US adapted a Rhesus monkey rotavirus strain MMU18006 as a live oral vaccine. This vaccine strain caused fevers in some infants between 5-12 months of age in industrialized countries but is well-tolerated by younger infants below 4 months of age in both developed and developing countries. Observations from epidemiological and volunteer studies show that an initial enterotoxigenic E. coli infection gives rise to a high level of immunity to the same strain but that about 5 separate clinical infections with distinct variants of enterotoxigenic E. coli are necessary to stimulate broad spectrum protection. Several new prototype Shigella vaccines have been reported recently. 1 is a Shigella sonnei/Salmonella typhi bivalent vaccine prepared by introducing the genes that enclode the production of the S. sonnei 0 antigen into an attentuated S. typhi vaccine strain Ty21a. It is 101 years since the 1st cholera vaccine candidate was administered to humans but the ideal cholera vaccine continues to remain illusive. Recent progress has yielded several promising candidates. For typhoid fever 2 attentuated strains of Salmonella typhi Ty21a developed by Swiss and 541 Ty by US scientists are being evaluated as live oral vaccines.