True statement about Vi polysaccharide vaccine is –
**Core Concept**
The Vi polysaccharide vaccine is a type of conjugate vaccine designed to protect against Vibrio cholerae infections. It contains a capsular polysaccharide antigen that is highly specific to this pathogen.
**Why the Correct Answer is Right**
The Vi polysaccharide vaccine works by inducing an immune response against the O-specific polysaccharide (Vi antigen) present on the surface of Vibrio cholerae bacteria. This antigen is a key virulence factor, allowing the bacteria to evade the host's immune system. The vaccine stimulates the production of antibodies that recognize and bind to the Vi antigen, thereby preventing the bacteria from adhering to and invading intestinal epithelial cells.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe the mechanism of action of the Vi polysaccharide vaccine.
**Option B:** This option is incorrect because it is not a true statement about Vi polysaccharide vaccine.
**Option D:** This option is incorrect because it is not a characteristic of the Vi polysaccharide vaccine.
**Clinical Pearl / High-Yield Fact**
It is essential to note that the Vi polysaccharide vaccine is not a live attenuated vaccine, and thus it does not cause the disease it protects against. This makes it a safe option for individuals with weakened immune systems or those who are immunocompromised.
**Correct Answer:** C.