Construction and evaluation of a O139Vibrio choleraevaccine candidate based on ahemAgene mutation

• Published in: Vaccine 2006-05, Vol.24 (18), p.3750
• 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: Bacteriology; Biosynthesis; Cholera; Genes; Mutation; Plasmids; Survival; Vaccines
• 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 ofVibrio choleraeO139. 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 1x1011CFU 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 1x106CFU 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 byV. choleraeO139.