<prompt> Most sensitive test for the diagnosis of herpes simplex HSV encephalitis is?Cerebrospinal fluid CSF protein analysisHSV cultureHSV IgG antibodyHSV polymerase chain reaction  <response>: Ans. D. HSV polymerase chain reactiona. HSV encephalitis is the most common cause of acute sporadic encephalitis in the world.b. 95 of cases are due to HSV1.c. Age distribution appears to be biphasic, with peaks at ages 5 to 30 years and more than 50 years of age.d. It may follow a primary infectionreactivation of latent virus in the neurons.e. HSV meningitis or encephalitis is difficult to diagnose by laboratory tests, as there is a low titer of virus present in the cerebrospinal fluid.f. Only PCR is sensitive enough to detect HSV DNA in the CSF. 