The bacteria that causes cholera (Vibrio cholerae) has been genetically modified to remove its ability to cause disease. The modifications were: deletion of the genes encoding the cholera toxin A-subunit (leading to attenuation); inactivation of the gene encoding haemolysin A (also leading to attenuation); and insertion of a mercury resistance operon from Shigella flexneri (as a selectable marker). The GM cholera vaccine is currently known as PXVX0200.
|Common Name:||Cholera bacterium|
|Scientific Name:||Vibrio cholerae strain 569B|
|Categories:||Loss of toxin expression/ Vaccine attenuation|
Gene inactivation/ Vaccine attenuation
Selectable marker expression
Purpose of the dealings with the GMOs:
PaxVax Australia will be conducting a clinical trial of a genetically modified cholera vaccine involving volunteers covering different age groups. This trial would form part of an international clinical trial and would involve up to 1000 participants in Australia. The purpose of the trial is to verify the effectiveness of the vaccine in producing an immune response against cholera.
Genetic elements responsible for conferring the modified traits:
Function of protein
Cholera toxin A subunit gene
|deletion of Cholera toxin A subunit||vaccine attenuation|
haemolysin A gene
|inactivation of haemolysin A gene||vaccine attenuation|
mercury resistance operon from Shigella flexneri NR1
|confers mercury resistance||selectable marker|