## **Core Concept**
The acellular pertussis vaccine is a type of vaccine used to protect against pertussis (whooping cough) and contains specific components of the *Bordetella pertussis* bacteria, rather than the whole bacteria. This makes it different from the whole-cell pertussis vaccine, which is not commonly used today due to its association with adverse effects.

## **Why the Correct Answer is Right**
The acellular pertussis vaccine typically contains inactivated pertussis toxin (PT) and filamentous hemagglutinin (FHA), along with possibly other components like pertactin (PRN) and fimbriae types 2 and 3. These components are enough to stimulate an immune response without causing the disease itself. The correct answer, which includes pertussis toxin and filamentous hemagglutinin, is a formulation that provides immunity against pertussis while minimizing adverse reactions.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option might lack one of the key components typically found in acellular pertussis vaccines, such as pertussis toxin or filamentous hemagglutinin, making it incomplete.
- **Option B:** Similarly, this option might include components not typically emphasized in the standard acellular pertussis vaccine formulations or miss critical components.
- **Option D:** This option could potentially include whole-cell pertussis components or other irrelevant antigens not characteristic of acellular pertussis vaccines.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that acellular pertussis vaccines are preferred over whole-cell pertussis vaccines for their better safety profile, especially in terms of reducing the risk of severe side effects like febrile seizures. The typical acellular pertussis vaccine components include pertussis toxin (PT), filamentous hemagglutinin (FHA), pertactin (PRN), and sometimes fimbriae (FIM).

## **Correct Answer:** B. Pertussis toxin and filamentous hemagglutinin.