Immune response of human volunteers and animals to vaccination with egg-grown influenza A (H1N1) virus is influenced by three amino acid substitutions in the haemagglutinin molecule

Inactivated subunit vaccines were prepared from high-growth reassortants derived from two separate egg isolates from a single clinical specimen of influenza A (H1N1) virus. One of these reassortants, NIB-14, was antigenically indistinguishable from isolates made in tissue culture, while the other, NIB-17, was antigenically different and typical of egg isolates. The viruses differed by three amino acid residues in the haemagglutinin (HA) molecule and the anti-HA serological response induced was studied in animal models and human volunteers. In the volunteer groups both vaccines induced very high levels of circulating haemagglutination inhibition antibodies but with different serological specificities. Both NIB-14 and NIB-17 vaccines induced high levels of cross-reactive antibodies capable of reacting with both strains, but only NIB-14 vaccine induced significant levels of strain-specific antibodies capable of reacting exclusively with the homologous strain. Antisera containing only cross-reactive antibodies proved as capable of virus neutralization as antisera containing high levels of strain-specific antibodies. We extended the argument that epidemic strains are antigenically more closely related to tissue culture isolates and established that viruses which differ by only single amino acids at critical points in the HA structure can induce a significantly different immune response when used as inactivated vaccines.

Genic amplification of the entire coding region of the HEF RNA segment of influenza C virus

In order to provide an easy and powerful analysis of influenza C viral HEF RNA segment of a recent strain, a combination of reverse transcription and the polymerase chain reaction was used. We amplified the entire coding region of the HEF gene of a laboratory strain of virus called C/Johannesburg/1/66, widely used for binding and esterase activity studies as well as that of a strain isolated in 1991 (C/Paris/145/91) from a patient suffering from severe flu syndrome. The sequences we amplified were about 2 kilobases long. In this work, we show that the forward 'universal primer' Uni1, which has been used for influenza A and B viruses cDNA syntheses can also be used for influenza C virus. The PCR primers were designed to contain restriction sites to make the PCR products ready to be used for further purposes. A restriction analysis of the PCR products combined with analyses of all the human influenza C virus HEF gene sequences published so far permitted the design of sets of oligonucleotides which can prime PCR on cDNA of unknown influenza C virus for cloning.

High growth reassortant influenza vaccine viruses: new approaches to their control

When a new strain of an influenza virus is required to be incorporated into influenza vaccine, attempts are made to recombine such strains with laboratory adapted viruses, which will grow to high titre in order to improve the yield of the vaccine strain. It is important that such high growth reassortant vaccine strains are not contaminated with genes coding for the antigenic determinants of the high growth laboratory strain. We describe the characterization of two recent high growth reassortants and the application of the polymerase chain reaction to ensure their genetic identity and purity.

A collaborative study to examine the sensitivity and reproducibility of assays for the detection of DNA in biologicals derived from continuous cell lines

This report describes the results of a collaborative study which was set up to examine the sensitivity and reproducibility of DNA assays performed by different laboratories. Fifteen laboratories analysed 12 samples containing different amounts of DNA and protein. The study revealed a high degree of variability between laboratories in determining the DNA content of the test samples.

Sequence analysis of the haemagglutinin (HA) of influenza A (H1N1) viruses present in clinical material and comparison with the HA of laboratory-derived virus

We used the polymerase chain reaction to amplify the HA1 coding region of influenza A (H1N1) viruses present in clinical material from recent cases of influenza in the U.K. Previously, we have demonstrated that isolation of human influenza viruses in embryonated hens' eggs selects variants which have amino acid substitutions in their haemagglutinin (HA) clustering around the receptor-binding site. Such egg-selected variants are often antigenically distinct from each other and from corresponding viruses isolated on mammalian cells. Since in general the virus used for vaccine production is an egg-adapted virus, it is important to determine the extent to which these variants are present in the natural virus which causes disease in man. To achieve this, amplified products from clinical material were cloned and many individual clones sequenced. Our results indicate that the HA of the naturally occurring virus is relatively homogeneous and represented by virus isolated in the laboratory on MDCK cells, whereas the variants isolated in eggs are present only at low levels in clinical material.

Facial reanimation after acoustic neuroma excision: the patient's perspective

Facial reanimation after acoustic neuroma excision is currently accomplished using a variety of surgical techniques. A multi-institutional survey of patient perceptions of facial reanimation success was accomplished by mailing a questionnaire to 809 randomly selected members of the Acoustic Neuroma Association. Four hundred sixty patients who underwent 296 reanimation procedures responded. Facial to hypoglossal nerve anastomosis, tarsorrhaphy, and upper eyelid implants were most frequently performed. The patient's estimations of initial deficit, spontaneous recovery, and overall satisfaction with the reanimation procedures are discussed.

The hemagglutinin of influenza B virus present in clinical material is a single species identical to that of mammalian cell-grown virus

When clinical specimens of influenza virus are adapted to grow in embryonated hens' eggs, variants are selected which have specific amino acid substitutions in the hemagglutinin (HA). In contrast, a single virus, distinct from any egg-adapted variant, is selected when virus is isolated on MDCK mammalian cell culture. We have utilized the polymerase chain reaction to determine the nature of the hemagglutinin of influenza B viruses present in clinical material prior to cultivation in the laboratory. Sequence analysis of individual clones of amplified DNA reveals that the HA of clinical virus is essentially homogeneous and identical to the virus derived on MDCK cells. The HA of egg-adapted virus was heterogeneous and nonidentical to that of the clinical material and of the MDCK-derived virus.

The antigenic structure of a human influenza A (H1N1) virus isolate grown exclusively in MDCK cells

A panel of monoclonal antibodies has been produced against a 1983 human influenza A (H1N1) virus that has been isolated and grown exclusively in MDCK cells. Several of these antibodies were used to select variants from MDCK-derived virus in cells and their epitopes were then located by determining the HA1 amino acid sequence. The operational antigenic map of the haemagglutinin indicates the presence of two distinct immunodominant antigenic regions which correspond but are not identical to antigenic sites Sa and Sb of the A (H1N1) virus A/PR/8/34. Also during this study, we characterized a unique group of antibodies for which variants require two distinct and specific HA1 amino acid substitutions to escape neutralization.

Analysis of the chromosomal location of two copies of a Bordetella pertussis insertion sequence

IS481v1 and IS481v2 are two copies of a Bordetella pertussis insertion sequence element. We have shown that IS481v1 is located within 3 kbp of the start of the adenylate cyclase gene whilst IS481v2 is immediately adjacent to the end of the agglutinogen 2 gene and provides the stop codon for that gene. In addition, IS481v1 and IS481v2 were present at these two specific sites in nine strains of B. pertussis, including two Phase IV strains which expressed neither adenylate cyclase nor agglutinogen 2 and three Phase I strains which did not express agglutinogen 2. The loss of expression in these strains is not the result of DNA rearrangements at the sites of IS481v1 or IS481v2.

Influenza A (H1N1) vaccine efficacy in animal models is influenced by two amino acid substitutions in the hemagglutinin molecule

The immunogenicity and protective efficacy of formalin-inactivated vaccines prepared from influenza A (H1N1) viruses grown in MDCK cells and in eggs was compared in animal models. The A/Chr/157/83 virus grown in MDCK cells (157M) differed by two amino acid substitutions in the HA molecule from the corresponding virus grown in eggs (157E) and the two viruses could be distinguished antigenically by monoclonal and polyclonal antibodies. Following two intramuscular injections of vaccine in ferrets, guinea pigs, and hamsters, both vaccines were equally immunogenic when antibody was analyzed by hemagglutination inhibition using homologous virus. However, single radial hemolysis analysis following antibody cross-adsorption showed that antibody stimulated by 157E vaccine was exclusively strain specific whereas that produced by the 157M vaccine was more broadly reactive. When immunized hamsters were challenged with virus cultivated on mammalian (MDCK) cells, the homologous vaccine induced a higher degree of protection than the corresponding egg-grown vaccine.

Analysis of separate isolates of Bordetella pertussis repeated DNA sequences

Two independent isolates of a Bordetella pertussis repeated DNA unit were sequenced and shown to be an insertion sequence element with five nucleotide differences between the two copies. The sequences were 1053 bp in length with near-perfect terminal inverted repeats of 28 bp, had three open reading frames, and were each flanked by short direct repeats. The two insertion sequences showed considerable homology to two other B. pertussis repeated DNA sequences reported recently: IS481 and a 530 bp repeated DNA unit. The B. pertussis insertion sequence would appear to comprise a group of closely related sequences differing mainly in flanking direct repeats and the terminal inverted repeats. The two isolates reported here, which were from the adenylate cyclase and agglutinogen 2 regions of the genome, were numbered IS48lvl and IS48lv2 respectively.

Sequence analysis of the hemagglutinin of B/Ann Arbor/1/86, an epidemiologically significant variant of influenza B virus

Influenza B/Ann Arbor/1/86 is representative of antigenic variants responsible for the most important influenza epidemics during the 1985/1986 season. The nucleotide sequence of the hemagglutinin HA1 region and the deduced amino acid sequence are presented. Compared to the previous winter's vaccine strain B/USSR/100/83, B/AA/1/86 possesses 18 amino acid substitutions and 2 amino acid insertions, 50% of which are distributed within the vicinity of the reported single immunodominant antigenic site.