Construction and characterization of an auxotrophic ctxA mutant of O139 Vibrio cholerae
| Autor: | T. Ledon, Melissa Chan, S. Kurunathan, T. Gim Cheong, R. Fando, Manickam Ravichandran, P. Lalitha, Zainul F. Zainuddin, M. Chandrika |
|---|---|
| Rok vydání: | 2010 |
| Předmět: |
Cholera Toxin
Operon Auxotrophy Enzyme-Linked Immunosorbent Assay Biology Vaccines Attenuated medicine.disease_cause Microbiology Vibrio cholerae O139 Mice Ileum Vibrionaceae medicine Animals Mice Inbred BALB C Virulence Cholera toxin Wild type Cholera Vaccines Aminolevulinic Acid medicine.disease biology.organism_classification Antibodies Bacterial Virology Cholera Infectious Diseases Amino Acid Substitution Vibrio cholerae Mutagenesis Site-Directed Mutant Proteins Antitoxins Rabbits Cholera vaccine |
| Zdroj: | Microbial Pathogenesis. 49:211-216 |
| ISSN: | 0882-4010 |
| DOI: | 10.1016/j.micpath.2010.06.001 |
| Popis: | Cholera caused by the O139 serogroup still remains a public health concern in certain regions of the world and the existing O1 vaccines do not cross-protect cholera caused by this serogroup. An aminolevulinic acid (ALA) auxotroph vaccine candidate against the O139 serogroup, designated as VCUSM2, was recently developed. It was found to be immunogenic in animal model studies but showed mild reactogenic effects due to the presence of two intact copies of Vibrio cholerae toxin (CTX) genetic element. In the present study we have modified the ctx operon by systematic allelic replacement methodology to produce a mutant strain, designated as VCUSM14. This strain has two copies of chromosomally integrated and mutated ctxA gene, encoding immunogenic but not toxic cholera toxin A subunit (CT-A). The amino acids arginine and glutamic acid at position 7th and 112th, respectively, in CT-A of VCUSM14 were substituted with lysine (R7K) and glutamine (E112Q), respectively. Two copies of the ace and zot genes present in the ctx operon were also deleted. Cholera toxin-ELISA using GM1 ganglioside showed that the both wild type CT and mutated CT were recognized by anti-CT polyclonal antibodies. VCUSM14 produced comparatively less amount of antigenic cholera toxin when compared to the VCUSM2 and Bengal wild type strain. VCUSM14 did not elicit fluid accumulation when inoculated into rabbit ileal loops at doses of 10(6) and 10(8) CFU. The colonization efficiency of VCUSM14 was one log lower than the parent strain, VCUSM2, which can be attributed to the ALA auxotrophy and less invasive properties of VCUSM14. VCUSM14, thus a non-reactogenic auxotrophic vaccine candidate against infection by O139 V. cholerae. |
| Databáze: | OpenAIRE |
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