ABSTRACT
Protective responses to influenza vaccine reassortants derived from the cold-adapted (ca) donor strains A/Leningrad/134/17/57 and B/USSR/60/69 and wild-type epidemic viruses were studied in two strains of mice. Preliminary experiments revealed that, when mixtures of three viruses were inoculated intranasally to mice with 50 microliters containing 10(6) EID50 per 200 microliters (10(5.4) EID50 per mouse), interference between strains did not occur. However, interference with the growth of the influenza reassortant B/60/32/R took place if its concentration in the mixture was reduced to 10(5) (10(4.4) per mouse) or if it was inoculated at 10(6) EID50 (10(5.4) per mouse) in the presence of the influenza reassortant R/34 and two other influenza A epidemic strains; interference was unrelated to serological responses to infection with B/60/32/R. Despite evidence of interference, mice inoculated with the same mixtures in two identical doses, three weeks apart, were able to clear a challenge from each of seven homotypic and heterotypic influenza A and B strains. Heterotypic clearance of influenza A challenge viruses was greater following mixed infection, indicating that common determinants within the surface antigen glycoproteins contributed to immune responses which were broader than could be expected to be induced by parenteral vaccination.
Subject(s)
Influenza A virus/immunology , Influenza B virus/immunology , Influenza Vaccines/immunology , Orthomyxoviridae Infections/prevention & control , Reassortant Viruses/immunology , Administration, Intranasal , Animals , Antibodies, Viral/blood , Cold Temperature , Influenza A virus/physiology , Influenza B virus/physiology , Male , Mice , Mice, Inbred BALB C , Mice, Inbred CBA , Orthomyxoviridae Infections/immunology , Reassortant Viruses/physiology , Species Specificity , Vaccination , Vaccines, Synthetic/immunology , Virus ReplicationABSTRACT
Two surface antigen segregants were prepared by co-infection of chicken embryo kidney cell cultures with reassortants of the cold-adapted influenza A master strain A/Ann Arbor/6/60-ca (H2N2) possessing the surface antigens of A/Queensland/6/72 (H3N2) and A/Hong Kong/123/77 (H1N1) and other genes that were common to the master strain. The segregants were shown by serological tests to possess H3N1 and H1N2 surface antigens but it was not possible to determine the presence of H1 or N1 genes by single-stranded RNA polyacrylamide gel electrophoresis. The immunogenic properties of A/Queensland/6/72-ca and H3N1 segregant CR6/35/2/9 were compared by immunising mice intranasally with graded doses of each virus twice at an interval of 3 weeks and then challenging with the wild-type A/Queensland/6/72 (H3N2). Clearance of the challenge virus occurred in mice immunised with the same vaccinating dose, indicating that the immunogenicity of both the ca H3N2 and H3N1 viruses was identical and similar findings were obtained for mice immunised with A/Hong Kong/123/77-ca and the H1N2 segregant CR6/35/1/19 and challenged with the wild-type A/Hong Kong/123/77. Therefore, there appears to be a good correlation between immunogenicity and the inheritance of the haemagglutinin gene.
Subject(s)
Adaptation, Physiological/immunology , HN Protein/immunology , Hemagglutinins, Viral/physiology , Influenza A virus/immunology , Reassortant Viruses/immunology , Adaptation, Physiological/genetics , Animals , Cells, Cultured , Chick Embryo , Cold Temperature , HN Protein/genetics , Hemagglutinin Glycoproteins, Influenza Virus , Hemagglutinins, Viral/genetics , Influenza A virus/genetics , Influenza A virus/physiology , Reassortant Viruses/genetics , Reassortant Viruses/physiologyABSTRACT
The nucleotide sequences of the neuraminidase (NA) genes of the A/Leningrad/134/57 (H2N2) wild-type (Len/wt) virus as well as two of its live attenuated, cold-adapted (ca) variants, A/Leningrad/134/17/57 (Len/17) and A/Leningrad/134/47/57 (Len/47), were determined. In comparison with Len/wt, one nucleotide change (C-225 to A) was found in the NA gene of Len/17. This change codes for a Thr-to-Asn substitution at position 69 of NA. The NA gene of the more attenuated Len/47 ca virus has one silent (T-814 to C) and two coding nucleotide substitutions, C-78 to T (Ala-20 to Val) and C-225 to A (Thr-69 to Asn). These sequence data were used to design a PCR-restriction technique to determine the origin of the NA gene in candidate live, attenuated vaccine reassortants made by reassorting these ca strains with current field viruses.
Subject(s)
Influenza A Virus, H2N2 Subtype , Influenza A virus/enzymology , Neuraminidase/genetics , Amino Acid Sequence , Base Sequence , DNA, Viral , Genetic Variation , Humans , Influenza A virus/genetics , Molecular Sequence Data , Reassortant Viruses/geneticsABSTRACT
Interference between pairs of cold-adapted (ca) influenza A and B vaccine reassortant viruses and between ca influenza B reassortant viruses and wild-type influenza strain A/PR/8/34 was studied in embryonated eggs and/or in the respiratory tract of three strains of mice. Interference in eggs between ca A and B reassortants occurred after 2 days but was masked by later cycles of growth. When doses of 10(6) EID50 of the reassortant viruses B/60/32/R and A/47/6/R were administered to outbred mice, interference with the growth of A/47/6/R occurred in the turbinates; interference with the growth of B/60/32/R did not occur. However, interference with the growth of B/60/32/R was noted in the lungs of Balb/c mice after co-infection with 10(6) EID50 of both A/PR/8/34 and B/60/32/R. Interference did not occur when the dose of B/60/32/R was increased to 10(7) EID50 per mouse. When CBA mice were co-infected with 10(6) EID50 of both B/60/32/R and the influenza A ca reassortant R/34, or 10(6) EID50 of B/60/32/R,R/34 and A/Leningrad/134/57, interference did not occur. Interference could not be detected in mice following dual infection from serum responses to individual viruses.
