Pasteurella multocida inactivated with ferric chloride and adjuvanted with bacterial DNA is a potent and efficacious vaccine in Balb/c mice.

PURPOSE: Pasteurella multocida (P. multocida) is a principal pathogen of domestic animals and an opportunistic pathogen of humans. It is the causative agent of pneumonia and haemorrhagic septicaemia in cattle, sheep and goats, fowl cholera in chickens and progressive atrophic rhinitis in swine. In this study, we investigated the humoral and cellular immune responses and protective immunity conferred by an iron-inactivated vaccine with bacterial DNA (IIV+bDNA) as an adjuvant in mice. METHODOLOGY: P. multocida was grown in BHI broth, inactivated with formalin and FeCl3 and adjuvanted with alum and bDNA. Mice were immunized with two whole-cell inactivated vaccine doses 2 weeks apart. The animals were challenged 4 weeks after booster immunization. Immunogens (vaccines and bDNA) posed no safety problems when mice were injected subcutaneously (s/c) with these preparations. The serum antibody titres were tested by ELISA. At 28 days post immunization, cell-mediated immunity responses were determined. The responses were measured by assay of IL-6 and IL-12 in lymphocyte spleen culture supernatants. RESULTS: ELISA results showed that the levels of antibodies in iron inactivated with bDNA adjuvant groups were higher than in the formalin inactivated with alum adjuvant vaccine group. The protection rate of IIV+bDNA adjuvant vaccine was superior to that of the other vaccines and it protected 100 % of the challenge group mice. Following immunization, bDNA promoted increased production of interleukins compared to the control groups. CONCLUSION: These studies indicate that bDNA is effective as an immune adjuvant, and along with stimulatory bDNA represent promising new humoral and cellular immune enhancers for vaccination applications. In addition, this vaccine is able to provide long-term protection against infection.

Prevalence of shiga toxins (stx1, stx2), eaeA and hly genes of Escherichia coli O157:H7 strains among children with acute gastroenteritis in southern of Iran.

OBJECTIVE: To survey the prevalence severe diarrhea arising from these bacteria in children under 5 years old in Marvdasht. METHODS: In this study faecal sample from 615 children aged <5 years old who were hospitalized for gastroenteritis in Fars hospitals in Iran were collected and then enriched in Escherichia coli (E. coli) broth and modified tryptone soy broth with novobiocin media. Fermentation of sorbitol, lactose and ß -glucoronidase activity of isolated strains was examined by CT-SMAC, VRBA and chromogenic media respectively. Then isolation of E. coli O157:H7 have been confirmed with the use of specific antisera and with multiplex PCR method presence of virulence genes including: stx1, stx2, eaeA, hly has been analyzed. RESULTS: E. coli O157:H7 was detected in 7 (1.14%) stool specimens. A significant difference was seen between detection rate of isolated bacteria from age groups 18-23 months and other age groups (P=0.004). Out of considered virulence genes, only 1 of the isolated strains (0.16%) the stx1 and eaeA genes were seen and also all isolated bacteria had resistance to penicillin, ampicillin and erythromycin antibiotics. CONCLUSIONS: We found that children < 2 years of age were at highest risk of infection with E. coli O157:H7. Regarding severity of E. coli O157:H7 pathogenesis, low infectious dose and lack of routine assay for detection of these bacteria in clinical laboratory, further and completed studies on diagnosis and genotyping of this E. coli O157:H7 strain has been recommended.