Antigenic Shift and Drift

Antigenic Drift Nature of antigenic variation: Minor Mechanism: Gradual accumulation of amino acid substitutions due to point mutation in the hemagglutinin (H) and neuraminidase (N) genes. As mutations accumulate, antibodies generated by exposure to previous strains do not neutralize current strains to the same extent,… Read More

Rickettsial Diseases Mnemonic

Rickettsia is a gram negative obligate intracellular parasite. As shown in the table above, human is only an incidental host except in louse-borne epidemic typhus. Disease Agent Vectors Typhus group Epidemic typhus or Brill Zinsser disease R. prowazekii Louse Murine/Endemic typhus R.typhi (R.mooseri) Flea Spotted… Read More