A 25-year-old male presents with a history of recurrent infections, particularly with Neisseria meningitidis. Laboratory investigations reveal a deficiency in a specific complement component. Which of the following complement component deficiencies is most likely responsible for his increased susceptibility to Neisseria infections?

Explanation

Deficiencies in the terminal complement components (C5, C6, C7, C8, C9), which form the Membrane Attack Complex (MAC), severely impair the body's ability to lyse Gram-negative bacteria. Neisseria species are particularly susceptible to MAC-mediated lysis, and thus, individuals with MAC deficiencies are highly prone to recurrent Neisseria infections. C1q deficiency is associated with immune complex diseases, C3 deficiency with broad susceptibility to pyogenic infections, and Factor B deficiency with impaired alternative pathway activation.