<prompt> It is determined an infant suffers from Brutons agammaglobulinemia. Which of the following pathogens will present the most serious threat to this child?Measles virusMycobacterium tuberculosisChlamydia trachomatisVaricella-zoster virus VZV  <response>: Brutons agammaglobulinemia is a congenital defect that becomes apparent at approximately 6 months of age when maternal IgG is diminished. The child is unable to produce immunoglobulins and develops a series of bacterial infections characterized by recurrences and progression to more serious infections such as septicemia. Cell-mediated immunity is not affected and the child is able to respond normally to diseases that require this immune response for resolution. 