Immunological interrelationships among human and non-human paramyxoviruses revealed by immunoprecipitation

Antigenic interrelationships among paramyxoviruses were examined by immunoprecipitation of isotope-labelled virus-infected cell lysates with specific antisera against virions or virus components. Sendai virus, human parainfluenza virus type 1 (Pa-1) and human parainfluenza virus type 3 (Pa-3) belonged to one antigenic group, and human parainfluenza virus type 2 (Pa-2), human parainfluenza virus type 4 (Pa-4), mumps virus (MuV) and simian virus 5 to a second group. Furthermore, the human paramyxoviruses Pa-1, Pa-2, Pa-3, Pa-4 and MuV formed a single antigenic group which overlapped the above groups. Although Newcastle disease virus (NDV) belonged to a separate group it showed some cross-reaction with the human paramyxoviruses. In particular, certain batches of anti-NDV antisera reacted with the fusion (F) polypeptide of Pa-2 and the reciprocal reaction of anti-Pa-2 antiserum with NDV F was also found. The nucleoprotein showed the broadest cross-reactions among these paramyxoviruses, whereas the matrix polypeptide exhibited antigenic individuality. The nucleoprotein of MuV was most cross-reactive. Pa-2 haemagglutinin-neuraminidase (HN) and anti-MuV HN serum showed cross-reactivity with various antisera and antigens.