Oral vaccine against cholera prepared from Vibrio cholerae antigen (s)
Chaicumpa, W.; Chaisri, U.; Tapchaisri, P.; Chongsa-Nguan, M.; Pongponratn, E.
Southeast Asian Journal of Tropical Medicine and Public Health 18(2): 142-148
ISSN/ISBN: 0125-1562 PMID: 3313733 Accession: 006041056
Albino rats aged 7-8 weeks old purchased from the National Laboratory Animal Centre, Salaya, Nakhon Pathom, were found to be a good animal model for the study on immunogenicity of V. cholerae antigens. Seventy-two rats were fasted for 15 hours before feeding each one with 1 ml of 5% NaHCO3 to reduce gastric acidity prior to immunization. They were divided into 9 groups of 8 rats and immunized orally with 2 ml, each, of the V. cholerae antigens dissolved or suspended in Cassamino acid as follows:- group 1 (control): Cassamino acid (Ca) alone; group 2 (control): 2.5% formalinized sheep red blood cells (F-SRBC); group 3: 1,000 .mu.g of lipopolysaccharide (LPS); group 4: 100 .mu.g of procholeragenoid (P): group 5: 80 hemagglutinating units of cell-bound haemagglutinin (CHA) adsorbed onto the surface of F-SRBC (CH-SRBC); group 6: 500 .mu.g of LPS + 50 .mu.g of P; group 7: CH-SRBC + 50 .mu.g of P; group 8: combined vaccine formula 1 consisted of 500 .mu.g of LPS, CH-SRBC and 50 .mu.g of P and group 9: combined vaccine formula 2 consisted of 1,000 .mu.g of LPS, CH-SRBC and 100 .mu.g of P. The immunization was repeated once more 14 days later. Five days, thereafter, the rats were killed and their jejuni were removed for cryostat sectioning. Antibody producing cells against LPS (anti-LPS cells), P (anti-CT cells) and CHA (anti-CHA cells) in the intestinal lamina propria were enumerated by double antibody sandwich method of immunofluorescence using pure LPS, cholera toxin (CT) and pure CHA as the antigens in the assay, respectively. The results of the experiments indicate that LPS and P are synergistic antigens while CHA and P are not. LPS acts as CHA adjuvant. A combined oral vaccine consists of LPS, CHA and P evokes the highest production of antibody producing cells of all specificities when they are combined in a sutiable proportion.