<prompt> In a patient with a Salmonella infection, which of the following mechanisms will most likely be the earliest adaptive response for clearing the infection while bacteria are present within intracellular endosomes?Antibody mediated neutralization of free bacteriaComplement mediated lysis of infected host cellsCTL recognition of bacterial peptides presented by MHC class IIDTH responses generated by CD4 T cells  <response>: Ans. dDTH responses are generally the first effective responses involved in clearance of intraendosomal microbes. Later in such infections, the microbes or their molecules may escape into the cytoplasm, making it possible for Cytotoxic T lymphocyte responses to develop. Complement does not clear active intracellular infections. Antibodies maybe effective in inhibiting reinfection but do not cleat active intracellular infections. 