Abstract: A method of propagating rotavirus in vitro which comprises growing the virus in cell cultures susceptible to the virus in the presence of a serum-free medium containing a proteolytic enzyme. Such a method promotes the growth of virus in tissue culture, thus providing large quantities of antigen for immunization and for use in diagnostic tests.

Abstract: A novel antigenic preparation which comprises a plurality of microvesicles which microvesicles are unilamellar bodies comprising a single lipid bilayer upon the exterior surface of which is bound an antigenic protein derived from a virus and having a hydrophobic region.

Abstract: A preparation of rotavirus inner capsid antigenic subunits which is substantially free from complete virus particles and fragments thereof. The subunits have a sedimentation coefficient of 17.5S, and a molecular weight of >2.times.10.sup.5 and >2.times.10.sup.6. Such a preparation can be prepared by suspending a sample of faecal material obtained from a mammal infected with rotavirus, incubating the suspension followed by the removal and concentration of the subunits from the suspension by centrifugation and/or filtration. Such a preparation is useful in several immunological tests and for the preparation of antisera also for use in tests.

Abstract: A novel antigenic preparation which comprises a plurality of microvesicles are unilamellar bodies comprising a single lipid bilayer upon the exterior surface of which is bound an antigenic protein derived from a virus and having a hydrophobic region.