Gram Negative Bacilli
Assertion: there is no successful vaccine against E. coli infection
Reason: serotypic diversity of both surface antigens and toxins
|A||Both Assertion and Reason are true, and Reason is the correct explanation for Assertion|
|B||Both Assertion and Reason are true but Reason is not the correct explanation for Assertion|
|C||Assertion is true but Reason is false|
|D||Reason is true but Assertion is false|
a.A fully successful vaccine against E. coli infection has not yet emerged, because of the serotypic diversity of both surface antigens and toxins.
b. However, trials have been conducted with toxoids based on the enterotoxins, purified fimbriae, whole killed organisms and live attenuated strains, all of which give some protection.
c.The combined killed cholera/B toxin subunit vaccine gives significant protection against ETEC because of cross-reaction between the two toxins