Construction and evaluation of a O139 Vibrio cholerae vaccine candidate based on a hemA gene mutation

• Published in: Vaccine 2006-05, Vol.24 (18), p.3750-3761
• Main Authors: Ravichandran, Manickam, Ali, Syed Atif, Rashid, Nur Haslindawaty Abdul, Kurunathan, Sinniah, Yean, Chan Yean, Ting, Lai Chin, Bakar, Afifi Sheikh Abu, Lalitha, Pattabiraman, Zainuddin, Zainul F.
• Format: Article
• Language: English
• Subjects: ALA auxotroph; Aldehyde Oxidoreductases - genetics; Animals; Antibodies, Bacterial - blood; Applied microbiology; Bacteriology; Biological and medical sciences; Cholera - prevention & control; Cholera Toxin - immunology; Cholera Vaccines - administration & dosage; Cholera Vaccines - genetics; Cholera Vaccines - immunology; Colony Count, Microbial; Disease Models, Animal; Fundamental and applied biological sciences. Psychology; hemA mutation; Immunoglobulin A - blood; Immunoglobulin G - blood; Intestine, Small - microbiology; Lipopolysaccharides - immunology; Mice; Mice, Inbred BALB C; Microbiology; Miscellaneous; Mutation; O139 Vibrio cholerae; Rabbits; Vaccine; Vaccines, antisera, therapeutical immunoglobulins and monoclonal antibodies (general aspects); Vaccines, Attenuated - administration & dosage; Vaccines, Attenuated - genetics; Vaccines, Attenuated - immunology; Vibrio cholerae; Vibrio cholerae O139 - genetics; Vibrio cholerae O139 - growth & development; Vibrio cholerae O139 - immunology; Virulence
• ISSN: 0264-410X; 1873-2518
• DOI: 10.1016/j.vaccine.2005.07.016

In this paper, we describe the development of VCUSM2, a live metabolic auxotroph of Vibrio cholerae O139. Auxotrophy was achieved by mutating a house keeping gene, hemA, that encodes for glutamyl-tRNA reductase, an important enzyme in the C5 pathway for δ-aminolevulenic acid (ALA) biosynthesis, which renders this strain dependent on exogenous ALA for survival. Experiments using the infant mouse and adult rabbit models show that VCUSM2 is a good colonizer of the small intestine and elicits greater than a four-fold rise in vibriocidal antibodies in vaccinated rabbits. Rabbits vaccinated with VCUSM2 were fully protected against subsequent challenge with 1 × 10 11 CFU of the virulent wild type (WT) strain. Experiments using ligated ileal loops of rabbits show that VCUSM2 is 2.5-fold less toxic at the dose of 1 × 10 6 CFU compared to the WT strain. Shedding of VCUSM2 in rabbits were found to occur for no longer than 4 days and its maximum survival rate in environmental waters is 8 days compared to the greater than 20 days for the WT strain. VCUSM2 is thus a potential vaccine candidate against infection by V. cholerae O139.