An antibody capture radioimmunoassay was established for the detection of coxsackievirus B4 and B5-specific IgM. A significant feature of the assay was the use of an unrefined coxsackievirus B (CBV) antigen. The antigen was prepared by freeze thawing, ultrasonication and low speed centrifugation of infected Vero cells with no purification or concentration of the antigen being performed. Results of sera tested were expressed as a serum ratio (SR) by comparison with a low positive control serum. To establish an SR indicating positivity in the assays, 100 antenatal sera collected in late February were tested. The mean SR was calculated and the mean plus three standard deviations was taken as the minimum SR indicating positivity. Although resulting in a relatively insensitive assay, such a value was required to exclude sera giving a low level of reactivity which may be due to residual enterovirus-specific IgM resulting from a remote infection.

The homologous CBV-IgM assay was positive in four cases of CBV4 infection and six cases of CBV5 infection. For the CBV4 IgM assay, ten of 20 (50%) sera from infections with CBV other than CBV4 were positive and nine of the 13(69%) sera from infections with echoviruses or coxsackieviruses A were positive. Five of 18 (27%) sera with an elevated CBV neutralization titre were positive in the CBV4-IgM assay. For the CB5-IgM assay seven of 18(39%) sera from infections with CBV other than CBV5 were positive and nine of 13 (69%) sera from infections with echoviruses or coxsackieviruses A were positive. The nine sera that were positive from this group in the CBV5-IgM assay were the same nine as were positive in the CBV4-IgM assay. Two of the 18(11%) sera with an elevated CBV neutralization titre were positive in the CBV5-IgM assay. These two sera were also positive in the CBV4-IgM assay and had an elevated monotypic CBV4 neutralization titre. None of the sera giving positive results gave significant reactivity when tested with control antigen. Twelve rheumatoid factor containing sera and 46 sera from other infections were negative in both assays. Of 24 sera from confirmed CBV infection, seven gave a positive monotypic CBV4 or 5-IgM response, ten were positive in both assays and seven were negative in both assays. The positive results seen with sera from cases of heterologous enterovirus infection may result from an anamnestic IgM response or, more likely, IgM directed against enterovirus cross-reacting antigens. The absence of homologous neutralizing antibody at a dilution of 1:20 in nine of 20 sera that gave a positive CBV-IgM result and the presence of positive results for CBV4 and 5-IgM in a 14 month old infant who had echovirus 7 infection indicates that the IgM need not be directed against neutralizing antigens.

Thus the CBV4 and 5-IgM assays developed appeared to be specific for an enterovirus infection but because of the cross-reactivity were not type-specific or group-specific.

Groups of volunteers were immunized subcutaneously with one of three inacti vated influenza virus A/USSR/77 (HlNl) vaccine preparations; a whole virus vaccine, a surface-antigen subunit adsorbed vaccine, or an aqueous surface-antigen subunit vaccine. The reactions to immunization were recorded, and the antibody response was measured 1 month later. A fourth group of volunteers were inoculated intranasally with live attentuated A/USSR/77 (H1N1) influenza virus; the reactions and antibody response of these volunteers were also measured. One month after immunization, the incidence of infection by challenge with homologous live attentuated virus was determined for all groups of volunteers. The results showed that all four vaccines used were relatively non-reactogenic, and that inactivated vaccines induced higher titres of serum antibody than the live attenuated vaccine. All the vaccines induced significant protection against challenge virus infection which was directly related to the level of serum HI antibody response.

Groups of volunteers were immunized with one of three influenza virus vaccines, and the resistance to challenge infection with attenuated influenza A (H1N1) virus was measured 8 months later. The vaccines were aqueous subunit influenza A/USSR/77 (H1N1) vaccine, aqueous subunit influenza B/Hong Kong/73 vaccine, or attenuated influenza virus A (H1N1) vaccine. The B virus vaccine was included as a control to assess the incidence of natural A virus infection during the study period. A proportion of the B virus vaccinees had pre-existing A (H1N1) virus antibody and were used to study the immunity conferred by natural infection to the live virus challenge. The serum antibody responses were measured at 1 and 8 months after immunization. The results showed that all the vaccines induced serum HI antibody in a proportion of the volunteers; however, after 1 month, higher titres of serum antibody were found in volunteers given inactivated A vaccine than in those given live attenuated A virus vaccine. Eight months post-immunization the titres of serum antibody in volunteers given inactivated vaccine had declined significantly, but there were no changes in the antibody titres of those given live virus vaccine. The incidence of infection by the challenge virus at 8 months post-immunization was directly related to the serum antibody titres 1 month post-immunization; no evidence was obtained to suggest that those given live virus vaccine had a more solid immunity than those given inactivated vaccine.

Serological responses to three bivalent aqueous equine influenza vaccines of different potency and an adjuvanted bivalent vaccine containing inactivated A/equine/Prague/56 (H7N7) and A/equine/Miami/63 (H3N8) viruses, were examined in seronegative ponies. Potencies of the vaccines, measured by single-radial-diffusion tests, ranged from 4 to 56 μg of haemagglutinin (HA) antigen activity/virus strain per dose. Serological responses to vaccination were examined by haemagglutination-inhibition (HI) and single-radial-haemolysis (SRH) tests.

Four weeks after a primary dose, HI responses to both vaccine viruses were barely detectable; after a second dose the HI responses to A/Miami/63 virus were low or undetectable but HI responses to A/Prague/56 virus were higher (17/20 ponies with titres ≤ 1:16). In contrast SRH tests revealed dose-related antibody responses to both virus strains after one and two vaccine doses; levels after the second dose were 2- to 5-fold higher than after the primary dose. Highest post-vaccination antibody titres were obtained with the adjuvanted vaccine which contained 2- to 4-fold less antigen (13–23 μg HA) than the most potent aqueous vaccine. Post-vaccination antibody reacted well in SRH tests with recent antigenic variants of equine influenza virus. A remarkable finding was the high rate of decline in antibody, detected by HI or SRH tests, following one or two doses of vaccine. Even in animals with the highest post-vaccine antibody levels 2–4 weeks after a booster dose, antibody levels had declined to low or undectable levels 14 weeks later. The low antibody titres detected at 14–32 weeks after vaccination were nevertheless vaccine dose-related.

Forty ponies immunized with inactivated virus vaccine containing A/equine/Miami/63 (H3N8) virus and six unvaccinated, seronegative ponies were experimentally challenged with a representative of recent equine H3N8 virus isolates, A/equine/Newmarket/79. All unvaccinated ponies became infected as judged by virus excretion, febrile responses and antibody responses, but only two of the vaccinated ponies were fully protected. Pre-challenge antibody levels to A/Newmarket/79 virus detected by single radial haemolysis (SRH) correlated well with the degree of clinical protection but the levels required for complete protection (SRH zones > 65 mm2) were high. The importance of these results in relation to conventional vaccination procedures against equine influenza is discussed.

Sera from people born between 1883 and 1930 and collected in 1977 were tested for the presence of HI antibodies to A/FM/1/47 (H1N1) virus and three recently (1977 and 1978) isolated influenza A-H1N1 viruses. The highest frequency of high-titred antibody to the four H1N1 viruses was detected in sera from people born in 1903–4, i.e. 42,54,38, and 22% had antibody against A/FM/1/47, A/Hong Kong/117/77, A/Brazil/11/78, and A/Fukushima/103/78 respectively. The birthdate groups 1896–1907 showed a higher percentage of HI antibody titres ≥18, ≥50, ≥100 or ≥1600 against the four H1N1 viruses than the birthdate groups 1907–30. This indicates the existence of an era, 1908–18, in which, apart from the H3N2 virus (1900–18), the H1N1 virus was epidemic among the human population.

A total of 1799 swine sera collected in Toyama prefecture in the central part of Japan during the years 1978–82 were tested for antibody against swine influenza virus (SIV), A/New Jersey/8/76 (H1N1). A high prevalence of antibody was observed in the years after the severe epizootic of SI, 34·5% in 1979 and 51·7% in 1982. In other years, the percentages of positive sera were low and ranged from 1·7 to 12·4%. Regional variations were seen in relation to a small scale epizootic. No antibody to SIV was detected in any of the sera collected during the warm season. In the following dry and cold winter, however, a severe epizootic occurred among the swine populations.

Eight sera from 125 cases of infectious mononucleosis (IM) were reactive for rubella-specific IgM in an M-antibody capture radioimmunoassay. The reactivity of individual sera varied depending upon the source of the rubella antigen used in the assay. One serum gave strongly positive results with some rubella haemagglutinating antigens but negative results with others and may have contained an IgM antibody which was capable of distinguishing between strains of rubella virus.

If the diagnosis of rubella is based solely on detection in solid-phase immunoassay of rubella-specific IgM, IM should be excluded.

Twenty-nine strains of Corynebacterium diphtheriae isolated from throats and 29 strains from skin lesions, the latter mainly from communities of low socio-economic status in tropics and cold climates, have been examined for the property of adherence to human buccal epithelial cells. All throat strains showed adherence. In contrast, strains from skin lesions were predominantly poor adherers. These results indicate that strains of C. diptheriae from throats must now be added to the important group of pathogens which possess the property of adherence to surface epithelial cells of mucous membranes, thus providing an essential first step in the process of colonizing their hosts. The possible role of this phenomenon of adherence to bucco-pharyngeal epithelial cells in the evolution of the host—parasite relationship of C. diphtheriae is discussed.

The properties of 48 cultures identified as Yersiniaenterocolitica or Y. enterocolitica like organisms, including Y. frederiksenii, Y. intermedia and Y. kristensenii, were examined. Of these, 39 were isolated from flieces of apparently healthy pigs, five from healthy cattle, one from an aborted bovine fetus, one from an aborted lamb and one from a lamb suffering from acute enteritis.

Most isolates from healthy animals were of Y. enterocolitica biotype 1 or Y. intermedia and belonged to O serogroups not usually associated with disease in man or animals.The isolates from abortion or enteritis cases were of Y. enterocolitica biotypes 3, 4 and 5 and belonged to the pathogenic serogroups 0:5b and 0:2a, 2b, 3. No organisms of serogroup 0:9 were found.

Faeces samples enriched for salmonellas in selenite F broth incubated at 43°C were subcultured to brilliant green MacConkey agar after 6 h. Four platings were made. As a control technique, each sample was enriched in selenite F incubated at 37°C for 24 h and subcultured once to brilliant green MacConkey agar. Of the specimens plated at 6 h, out of a total of 25 positive samples, 6 required more than a single subculture to reveal the presence of salmonellas. Twenty-four positive isolations were made from the selenite broths incubated at 37°C for 24 h and subcultured once only. All faecal samples positive by enrichment were also positive by direct plating. Nine samples seeded by 6 h produced only 1–2 salmonella colonies per plate. Convalescent specimens are, therefore, unlikely to be efficiently diagnosed by early subculture even if it is combined with multiple plating.

River Taff samples, after pre-enrichment in buffered peptone water, were enriched in Rappaport's medium at 37°C for 6 h. Subcultures were made to four plates of brilliant green MacConkey agar. A control subculture was made at 24 h to a single plate of brilliant green MacConkey. Although multiple subculture at 6 h improved salmonella isolation, the method was not as efficient as a single plating from the same enrichment culture at 24 h. There was no evidence that subculture at 6 h combined with multiple plating had a value either for faecal examination or for the isolation of salmonellas from sewage-polluted natural water.

Samples of other natural waters submitted routinely by Environmental Health Officers were pre-enriched in buffered peptone water before subculture to Rappa port's medium. The enrichment cultures were incubated at 37°C for 24 h and duplicate platings were made to brilliant green MacConkey agar. By double plating at 24 h, a gain of 16% in salmonella recovery was made. This compares favourably with the gain obtained by subculture from Rappaport after 24 and 48 h incubation. It also saves 24 h in examination time.

Much evidence of immunogenic heterogeneity among the LC strains of Mycoplasma mycoides ssp. mycoides emerged from cross-immunization and hyperimmunization experiments in mice in which three LC strains (Vom/Plum Island, 74/2488, and Mankefår 2833) were used for challenge purposes. All heterologous LC-strain vaccines cross-immunized against the three challenge strains, but protection was usually only ‘partial’, i.e. significantly less than that given by homologous vaccine. Cross-hyperimmunization with all heterologous LC but not SC strains produced protection against challenge with Vom/Plum Island that was virtually ‘complete’, i.e. similar to that produced by homologous vaccine. Challenge with 74/2488 gave generally similar results; but against Mankefår 2833 six heterologous LC vaccines gave complete protection and six did not.

Vaccines prepared from the Smith (1423) strain of M. mycoides ssp. capri gave some protection against Vom/Plum Island but none against 74/2488 or Mankefrr 2833. The cross-immunizing ability of three further M. mycoides ssp. capri strains appeared to resemble that of Smith (1423).

In a cross-hyperimmunization experiment, vaccines prepared from SC strains of M. mycoides ssp. mycoides varied greatly in their ability to protect against challenge with strains 74/2488 and Mankefår 2833.

Aqueous suspensions of virulent Legionellapneumophila grown on solid medium retained virulence and aerosol survival characteristics for several months. Significant numbers of viable organisms were recovered from aerosols held at various relative humidities (r.h.) for up to 2 h. The organisms survived best at 65% r.h. and were least stable at 55% r.h.

Exponential phase broth-grown organisms survived poorly in aerosols in comparison with stationary phase broth cultures or organisms grown on solid medium, suggesting that the metabolic status of Legionella pneumophila organisms may be an important factor affecting their ability to survive in aerosols and cause respiratory disease.

Epidemiological analysis of Klebsiella strains from nosocomial infections needs a simple, stable and reproducible technique of typing. We have evaluated three bacteriocin typing methods for Kiebsiella spp. by means of 15 bacteriocin-producing strains, with special reference to stability and reproducibility.

With the three methods indicator strains and clinical strains were retyped on different days under constant test procedures. Stability of bacteriocins was tested by titration immediately after preparation and after 4 weeks of storage at –70°C. Thereafter, reproducibility of typing was tested by means of these freshly prepared bacteriocin lysates and of portions of the same lysates stored at –70 °C. A moderate reproducibility was obtained with one method after two typing experi ments: 79.2% and 61.3% for indicator strains and clinical strains respectively. The other two methods gave a much lower reproducibility of 38 .5% and 32.5 % for indicator strains and of 11.1% and 25.5% for clinical strains after two experiments.

The reproducibility decreased after retyping three, four or five times. These methods are simple to perform but their usefulness for epidemiological studies is doubtful. Possible causes of the lack of reproducibility of the methods are discussed.

Natural isolates of Escherichia coli, Salmonella typhimurium, Klebsiella pneumoniae, and Providencia stuartii were analysed to determine their plasmid content. This data allowed the identification of nosocomial strains of K. pneumoniae and P. stuartii and helped in the differentiation of epidemic strains of E. coli 0111 and S. typhimurium. Phenotypically similar isolates of S. typhimurium could be shown to be of independent origin using plasmid pattern analysis. The dissemination of a particular plasmid through different strains of S. typhimurium resulted in a simulation of a very widely distributed epidemic strain, because the plasmid interfered with the phage type of its host strain in addition to determining re sistance properties. Plasmid pattern analysis disclosed two independently existing but interacting epidemic processes: a bacterial ‘epidemic’ strain may become disseminated over a large territory and may predominate there for a long time; a single plasmid, however, may also become distributed through many different bacterial strains and may spread over a large territory. Plasmid pattern analysis provides a valuable and universal epidemiological laboratory method.

Over a period of about 1 year, otitis externa occurred in at least 300 visitors to a recreational park. The infections were associated with the presence of Pseudomonas aeruginosa in insufficiently chlorinated whirlpools.