»Mumps Virus Vaccine Live conforms to the regulations of the FDAconcerning biologics (630.50to 630.57)(see Biologics á1041ñ).It is a bacterially sterile preparation of live virus derived from a strain of mumps virus tested for neurovirulence in monkeys,and for immunogenicity,free from all demonstrable viable microbial agents except unavoidable bacteriophage,and found suitable for human immunization.The strain is grown for the purpose of vaccine production on chicken embryo primary cell tissue cultures derived from pathogen-free flocks,meets the requirements of the specific safety tests in adult and suckling mice;the requirements of the tests in monkey kidney,chicken embryo and human tissue cell cultures and embryonated eggs;and the requirements of the tests for absence of Mycobacterium tuberculosisand of avian leucosis,unless the production cultures were derived from certified avian leucosis-free sources and the control fluids were tested for avian leucosis.The strain cultures are treated to remove all intact tissue cells.The Vaccine meets the requirements of the specific tissue culture test for live virus titer,in a single immunizing dose,of not less than the equivalent of 5000TCID50(quantity of virus estimated to infect 50%of inoculated cultures ×5000)when tested in parallel with the U.S.Reference Mumps Virus,Live.It may contain suitable antimicrobial agents.