Maurice A. Mufson

Two distinct subtypes of human respiratory syncytial virus.

Antigenic variation of human respiratory syncytial (RS) virus strains was analysed using a collection of nine, six, six, nine and one monoclonal antibodies respectively directed against the large glycoprotein (G), fusion protein (F), matrix protein (M), nucleoprotein (NP) and phosphoprotein (P) components of the Long strain of RS virus. A comparison was made with seven other strains isolated during different years in radioimmune precipitation analyses and immune fluorescence tests. Two different subtypes of the virus were demonstrable. Subtype A included the prototype strains Long and A2 and virus isolates from 1973, 1983 and 1984; subtype B included four virus strains isolated in successive years from 1979 to 1982. Subtype A viruses reacted with all the antibodies, whereas subtype B viruses showed different epitope characteristics in four structural components. The number of altered epitopes were 5/6, 1/2, 2/6 and 1/6 in the G, F, M and NP components, respectively. It is concluded that the two subtypes have evolved separately. The finding of two subtypes may explain previously observed strain variations in neutralization tests, and gives a new perspective on the immunobiology of RS virus.

Bacteremic pneumococcal pneumonia in one American city: a 20-year longitudinal study, 1978–1997

A surveillance of bacteremic pneumococcal pneumonia was conducted in Huntington, West Virginia, from 1978 to 1997 to investigate case-fatality rates, incidence of disease, capsular types, and antibiotic usage. Our study population comprised consecutive inpatients admitted to the hospitals in Huntington, West Virginia, and included 45 children younger than 15 years and 328 adults. All blood isolates were serotyped by capsular swelling procedures; clinical characteristics, treatment, and outcome for all patients were abstracted from hospital charts. The overall case-fatality rate was 20.3%, with most deaths occurring among adults older than 50 years. Case-fatality rates peaked at 37.7% among patients 80 years of age and older. Only 1 of 45 (2.2%) children died. Case-fatality rates declined in each successive 5-year period, from 30.2% in 1978-1982 to 15.6% in 1993-1997. In that same period, incidence rates increased severalfold among children younger than 4 years to 44.5 cases per 100,000 population and among adults 70 years and 80 years of age and older to 38.5 and 76.2 cases per 100,000, respectively. Of the 34 serotypes isolated, 10 accounted for two thirds of the cases of pneumonia: 1, 4, 9, 14, 3, 6, 12, 5, 23, and 19 (in rank order). Chronic renal disease and arteriosclerotic heart disease increased the risk of death. Treatment regimens that included a macrolide and a penicillin or cephalosporin resulted in the lowest case-fatality rate in adults older than 50 years: 6% in 1993-1997. In conclusion, as bacteremic pneumococcal pneumonia evolved over time, the case-fatality rate decreased, its incidence increased, predominant capsular types changed, and treatment regimens that included a macrolide resulted in the lowest fatality rates.

Prospective Study of Prognostic Factors in Community-Acquired Bacteremic Pneumococcal Disease in 5 Countries

To define the influence of prognostic factors in patients with community-acquired pneumococcal bacteremia, a 2-year prospective study was performed in 5 centers in Canada, the United States, the United Kingdom, Spain, and Sweden. By multivariate analysis, the independent predictors of death among the 460 patients were age >65 years (odds ratio [OR], 2.2), living in a nursing home (OR, 2.8), presence of chronic pulmonary disease (OR, 2.5), high acute physiology score (OR for scores 9-14, 7.6; for scores 15-17, 22; and for scores >17, 41), and need for mechanical ventilation (OR, 4.4). Of patients with meningitis, 26% died. Of patients with pneumonia without meningitis, 19% of those with >/=2 lobes and 7% of those with only 1 lobe involved (P=.0016) died. The case-fatality rate differed significantly among the centers: 20% in the United States and Spain, 13% in the United Kingdom, 8% in Sweden, and 6% in Canada. Differences of disease severity and of frequencies and impact of underlying chronic conditions were factors of probable importance for different outcomes.

Preparation and Characterization of Monoclonal Antibodies Directed against Five Structural Components of Human Respiratory Syncytial Virus Subgroup B

Mouse hybridomas producing antibodies against the structural proteins of strain WV4843, a subgroup B strain of respiratory syncytial (RS) virus, were produced by fusion of Sp2/0 myeloma cells with spleen cells from BALB/c mice immunized with purified preparations of the virus. After immunoprecipitation test with [35S]methionine-labelled extracellular virions, 35 clones found to produce antibodies against the fusion (F) protein, six against the member (M) protein, 21 against the nucleocapsid (NP) and eight against the phospho- (P) protein were further characterized. Immunoprecipitation with [3H]glucosamine-labelled intracellular virus polypeptides detected nine hybridoma cell lines producing antibodies against the large glyco- (G) protein of the virus. By competitive binding ELISA tests with monoclonal antibodies against each of the structural components, a minimum of two, 24, four, 15 and three epitopes were detected on the G, F, M, NP and P proteins, respectively. Eleven monoclonal antibodies directed against nine epitopes of the F protein could neutralize the infectivity of the virus. In contrast, none of the nine monoclonal antibodies against G could neutralize the infectivity of the virus. In order to find out more about the antigenic relationship between human and bovine RS virus strains all monoclonal antibodies were reacted with subgroup A RS virus and also with three different strains of bovine RS virus and one strain of caprine RS virus in immunofluorescence, ELISA and immunoprecipitation tests. In addition, 31 previously developed monoclonal antibodies against subgroup A virus were reacted with the bovine and caprine strains. The numbers of monoclonal antibodies of subgroup B specific for the B type of the two human subgroups were 9/9, 3/35, 0/6, 0/21, 0/8, for the G, F, M, NP and P proteins, respectively. No antigenic variations were found between the three bovine strains and the caprine strain. They did not react with the nine monoclonal antibodies against the G protein of subgroup B, nor did they react with nine monoclonal antibodies against subgroup A. Most but not all of the monoclonal antibodies against the other structural proteins of the two human RS virus subgroups reacted with the four strains. All 11 monoclonal antibodies against the F protein of subgroup B that could neutralize the infectivity of subgroup B also reacted with the bovine strains and neutralized their infectivity. It is concluded that although the bovine strains share many epitopes with the two human subgroups, they are antigenically distinct from the human viruses.

Molecular Epidemiology of Streptococcus pneumoniae Causing Invasive Disease in 5 Countries

A multicenter study was done during 1993-1995 to investigate prospectively the influence of several prognostic factors for predicting the risk of death among patients with pneumococcal bacteremia. Five centers located in Canada, the United Kingdom, Spain, Sweden, and the United States participated. Clinical parameters were correlated to antibiotic susceptibility and serotyping of the 354 invasive pneumococcal isolates collected and to molecular typing of 173 isolates belonging to the 5 most common serotypes (14, 9V, 23F, 3, and 7F). Serotype 14 was the most common among all isolates, but serotype 3 dominated in fatal cases and in isolates from Spain and the United States, the countries with the highest case-fatality rates. Fewer different patterns were found among the type 3 isolates, which suggests a closer clonal relationship than that among isolates belonging to other serotypes. Of type 3 isolates from fatal cases, 1 clone predominated. Other penicillin-susceptible invasive clones were also shown to spread in and between countries.

Coronavirus Infection in Acute Lower Respiratory Tract Disease of Infants

Abstract A serologic surveillance of lower respiratory tract disease in 417 hospitalized children under 18 months of age revealed infection with coronviruses (strains OC43 and/ or 229E) in 34 (8.2%). During the same interval, one of 13 control infants was infected. There were two distinct periods lasting six and 14 weeks, respectively, during which the incidence rose to as high as 18.9 % of patients with lower respiratory tract disease. The incidence of coronavirus infection in patients with pneumonia and bronchiolitis was higher than the incidences of adenoviruses, influenza, parainfluenza viruses types 1 and 2, and rhinoviruses, and lower only than the incidences of parainfluenza virus type 3 and respiratory syncytial virus. Coronoviruses serologically similar or identical to strain 229E were recovered from frozen nasal washes obtained during the acute phase of pneumonia in two children.

Revaccination with pneumococcal vaccine of elderly persons 6 years after primary vaccination.

We vaccinated 15 persons, age 56 to 79 years, with 14-valent pneumococcal polysaccharide vaccine and revaccinated them with 23-valent vaccine 6 years later to assess adverse reactions and booster responses of anticapsular antibodies. No systemic reactions occurred after administration of either vaccine. After booster vaccination, five vaccinees developed only mild soreness or tenderness at the site of injection. The (arithmetic) mean antibody level to 12 capsular types measured by radioimmunoassay increased 3.1-fold 1 month after the first vaccine; the range was 1427-5124 ng antibody nitrogen per ml (N ml-1). Six years later, mean antibody levels waned to about half these levels. One month after administration of the second dose of vaccine, the mean antibody level increased 1.5-fold; the range was 1011-3954 ng antibody N ml-1. Revaccination with pneumococcal vaccine of elderly persons can be carried out safely; the levels of anticapsular antibody achieved after revaccination are about half the levels after primary vaccination.

Pneumococcal Antibody Levels One Decade After Immunization of Healthy Adults

ABSTRACT: The authors investigated the persistence of anticapsular pneumococcal antibodies in 21 subjects one decade after administration of a single dose of a polyvalent pneumococcal polysaccharide vaccine. Fourteen vaccinees received a hexavalent vaccine composed of the polysaccharides of capsular types 1, 3, 4, 7F, 8, and 12F; four vaccinees received an octavalent vaccine consisting of these six polysaccharides and also those of capsular types 14 and 19F; and three vaccinees received a nonavalent vaccine that also included type 5 capsular polysaccharide. Antibody was measured by radioimmunoassay. The authors detected persistently elevated anticapsular antibody levels among more than one half of vaccinees who developed a significant rise in antibody 1 month following immunization one decade after administration of pneumococcal polysaccharide vaccine when these levels were compared to prevaccine levels for pneumococcal capsular types 4, 7F, and 8. This finding was not the case with pneumococcal types 1, 3, 12F, 14, and 19F; less than two fifths of vaccinees maintained increased levels of anticapsular antibody to these types one decade after administration of pneumococcal vaccine. Geometric mean anticapsular antibody levels for types 7F and 8 only were significantly higher one decade after vaccine administration compared with the levels before immunization (t-test, p < 0.01).

Antigenic and Genetic Diversity among the Attachment Proteins of Group A Respiratory Syncytial Viruses That Have Caused Repeat Infections in Children

Antigenic differences between the two major groups of respiratory syncytial (RS) virus may contribute to reinfections with these viruses. Additional variability occurs within the two major groups; the importance of intra-group variability in reinfections with RS virus has not been defined. Two pairs of group A viruses that had caused sequential infections in children showed G protein amino acid differences of up to 15%. Vaccinia viruses were constructed that expressed the G proteins from 2 of the paired group A isolates. Immunization of cotton rats with the recombinant vaccinia viruses provided equal protection against intranasal challenge by either of the RS viruses. Despite the amino acid differences between the two group A RS virus G proteins, these animal studies did not reveal differences in protection after immunization with the two G proteins. Precise definition of the role of RS virus antigenic variability in the establishment of reinfections in humans will require further investigations in humans.

Respiratory Syncytial Virus: Heterogeneity of Subgroup B Strains

In order to investigate further possible structural differences among the two subgroups of respiratory syncytial virus (RSV), we analysed the antigenic characteristics and size of structural proteins of 20 subgroup A and 43 subgroup B strains by their reactions with monoclonal antibodies (MAbs) directed against the proteins of RSV using immunofluorescence, ELISA and radioimmunoprecipitation assays. The latter test also enabled determination of the size of different structural components. The 37 MAbs employed were generated by immunization with both subgroup A and B strains. They represented specificities for distinct epitopes on five different structural proteins. The subgroup A strains proved to be relatively uniform. The fusion (F) protein, nucleoprotein (NP) and matrix (M) proteins of all strains tested had the same Mr and all except one strain had a phosphoprotein (P protein) of the same Mr. The F and P proteins were lower in Mr in B strains compared to A strains, which confirmed previous findings. The Mr of the large surface glycoprotein (G protein) of subgroup A strains varied slightly, probably on the basis of differing glycosylation. By contrast, the subgroup B strains exhibited substantial variation in the Mr of the G and also the P proteins and in reactivity with MAbs directed against the G and F proteins. Three size classes of the P protein were identified in B strains: 33K to 34K, 32K to 33K, and 31K to 32K. Twenty-seven subgroup B strains failed to react with four anti-G MAbs representing a single epitope, G2; the remaining 16 strains reacted with these MAbs. We designated these two sets of variants of B strains B1, which lacked the epitope, and B2, which had the epitope. The B1 strains also varied in the size of the G and P proteins. In contrast, all B2 strains had large G proteins and all except two strains had relatively large P proteins (33K to 34K). All subgroup B1 and B2 strains exhibited the same sizes of NP, F and M proteins. We conclude that the subgroup B strains of RSV include two variants, B1 and B2, and that the major difference between them resides in the G and P proteins.