Rubini, a new live attenuated mumps vaccine virus strain for human diploid cells.

A new, live attenuated mumps vaccine virus strain for human diploid cells has been developed at the Swiss Serum and Vaccine Institute, Berne. The Rubini virus was derived from a child of the same name possessing typical clinical signs and symptoms of mumps infection. Attenuation of the wild virus was performed by isolation and serial passage in WI-38 human diploid cells, specific pathogen-free hens' eggs and MRC-5 human diploid cells. The attenuated virus has been examined in respect of identity, freedom from adventitious agents and growth potential in MRC-5 cells. Furthermore, it does not evoke any clinical reactions in either baby or adult monkeys. It is characterized by the production in Vero cells of smaller plaques than are elicited by either the Jeryl Lynn or Urabe mumps virus strains. The reactogenicity and immunogenicity of the Rubini virus for man was studied by administering a monovalent vaccine to 13 adult male volunteers and a trivalent human diploid cell Rubini, measles (Edmonston-Zagreb-19 virus strain) and rubella (RA 27/3 virus strain) vaccine to 60 children ranging in age from 15 to 24 months. No reactions were observed. Seroconversion was obtained in 95% of the vaccinees, who developed a mean 50% neutralizing antibody titre of 1:64 after 6-8 weeks. Sensitization to avian and other animal proteins and antibiotics which may follow the use of most of the currently available measles-mumps-rubella vaccines, either single or combined, may be expected to be eliminated when this new vaccine is used. Its use in persons already sensitized to such products should furthermore induce no anaphylactic reactions.