<prompt> Trivalent oral polio vaccine contains type 3 virus -100,000 TCID 50200,000 TCID 50300,000 TCID 50400,000 TCID 50  <response>: Ans. is c i.e., 300,000 TC1D 50 Oral sabin polio vaccineo It contains live attenuated vimss type 1, 2 and 3 grown in primary monkey kidney or human diploid cell culture,o The vaccine containsOver 300.000 TCID 50 of type poliovirusOver 100,000 TCID 50 of type 2 poliovirusOver 300,000 TCID 50 of type 3 polioviruso Dose - 2 drop 0.1 mlo Schedule in National Immunization Programme of India.DoseAgeOPV-O Zero doseAt birthOPV-1OPV-26 weeks10 weeksOPV-314 weeksOPV-B Booster dose16-24 monthso Development of immunity - OPV induces local intestinal immunity by production of secretory- IgA as well humoral immunity by inducing production of serum antibodies IgG. So, it gives protection from paralysis and also prevents infection of the gut by wild viruses. 