Biomedical subjects
M A Mufson
Publications and source records attributed to M A Mufson.
Antibody responses of children to the C-terminal peptide of the SH protein of respiratory syncytial virus and the immunological characterization of this protein.
The SH protein of RSV, a small integrated hydrophobic membrane protein, consists of 64 amino acid residues in the polypeptide of subgroup A and 65 amino acid residues in the polypeptide of subgroup B. We synthesized five peptides, representing the SH protein of each RSV subgroup comprised of the following amino acid residues: 2-16, 12-26, 35-49, 45-60, and for subgroup A, 51-64 and for subgroup B, 51-65. Peptides 2-16 and 51-64/65 represented the N-terminal and C-terminal ends of the protein, respectively. In RIPA, under reducing conditions with mercaptoethanol, hyperimmune guinea pig (GP) serum against C-terminal peptide of the two subgroups precipitated the homologous 7.5 kDa and 21-30 kDa SH proteins. Under nonreducing conditions, the GP antipeptide sera precipitated all three SH proteins, suggesting that the 13-15 kDa protein exists as a dimer. The subgroup A 7.5 and 13-15 kDa proteins had apparent molecular weights about 1-2 kDa higher than the corresponding subgroup B proteins. The C-terminal peptides of subgroups A and B were used to characterize the immune response of 11 children, age 1 month to 1 year, with presumed primary RSV infection. Three of 4 children with subgroup A infection and 4 of 7 children with subgroup B infection developed homologous 4-fold rises in antibody to C-terminal peptide (aa 51-64/65) during convalescence. Except for one child with subgroup A and one child with subgroup B infection, the other 5 children developed heterologous rises also.(ABSTRACT TRUNCATED AT 250 WORDS)
Antibody to capsular polysaccharides of Streptococcus pneumoniae: prevalence, persistence, and response to revaccination.
The prevalence of immunity to Streptococcus pneumoniae in the adult population of the United States is unknown. In the study described herein, military recruits had anticapsular IgG antibody to only 15% of common pneumococcal serotypes, whereas working men and elderly men had IgG antibody to 33% and 34% of the common serotypes, respectively (P < .001). Among eight elderly subjects, the prevalence of IgG antibody to capsular polysaccharides increased from 30% to 78% after pneumococcal vaccination; 6 years thereafter, the rate of positive reactions had declined to 58% and IgG levels had declined substantially. With revaccination, IgG levels returned to within (+/-) 40% of the original postvaccination levels. IgM and IgG antibody appeared or began to increase in titer 6 days after vaccination; the rate and degree of response were the same after the first and second exposures. Since most individuals rapidly develop IgG antibody after colonization by S. pneumoniae and since IgG confers immunity, these data suggest that pneumonia is infrequent among healthy adults not because preexisting immunity is widespread but because--with colonization--an immune response develops rapidly, preceding specific events that might lead to infection. Our findings support recommended vaccination procedures and suggest that wider application in subsets of healthy younger adults should be considered.
Deaths in bacteremic pneumococcal pneumonia. A comparison of two populations--Huntington, WVa, and Stockholm, Sweden.
The case fatality rate in bacteremic pneumococcal pneumonia (Pnb) has been reported to be lower in Sweden than in the United States. We retrospectively compared 231 adult Pnb patients in Stockholm (STO), Sweden, with 107 patients infected with the same serotypes or groups in Huntington, WVa (HWV). The total case fatality rate was 11/231 (5 percent) in STO versus 28/107 (26 percent) in HWV (p < 0.001), being significantly lower in STO for all age groups. Patients from HWV more often had preexisting chronic diseases, while alcoholism was more prevalent in STO. The case fatality rate was similar among alcoholics in STO and HWV, while it was much higher in nonalcoholic patients with chronic diseases in HWV (22/73;30 percent) than in STO (2/88;2 percent) (p < 0.001). No bias was found that could account for more than a small part of the higher case fatality rate in HWV. Thus, underlying chronic diseases in HWV accounted for some of the increased risk of death in this patient group. However, the major part of the difference in death rates between HWV and STO remains unexplained.
Shedding of infectious virus and virus antigen during acute infection with respiratory syncytial virus.
Shedding of respiratory syncytial virus (RSV) in nasopharyngeal aspirates (NPA) of hospitalized children with acute respiratory infection was studied using direct antigen detection by time-resolved fluoroimmunoassay, rapid identification of infectious virus in centrifugally inoculated cell cultures by immunoperoxidase staining and conventional virus culture. Sequential NPAs, in which also local RSV-specific IgA response was measured, were collected from children with proven RSV infection. The shedding pattern was similar for both infectious virus and viral antigen. The overall agreement of the three methods was good (81%) in diagnostic specimens collected on admission, but markedly reduced (46%) in follow-up specimens. Secretory IgA was abundant in specimens giving discrepant or negative results only. The proportion of patients who shed RSV was high (> or = 87%) in the first week after onset of symptoms, and decreased sharply in the second week. An opposite temporal pattern was found in the proportion of patients with detectable RSV-IgA in their secretions. Sequentially isolated strains were antigenically stable as determined by their reactivity with a large panel of monoclonal antibodies. The findings suggest that RSV shedding should be monitored by using more than one method for virus detection.
Distinguishing between respiratory syncytial virus subgroups by protein profile analysis.
We subgrouped 75 strains of respiratory syncytial virus by a protein profile method (PPM) which relies on different mobilities of the phosphoprotein in one-dimensional polyacrylamide gel electrophoresis and does not require monoclonal antibodies. When compared with enzyme immunoassay, PPM correctly subgrouped 54 of 56 subgroup A and all 19 subgroup B strains.
Identification of subgroups of bovine respiratory syncytial virus.
The occurrence of antigenic variation among nine isolates of bovine respiratory syncytial virus (BRSV) was determined by examining their reaction patterns to human respiratory syncytial virus (HRSV) subgroup A and B monoclonal antibodies (MAbs) by enzyme immunoassay and radioimmunoprecipitation with fractionation by sodium dodecyl sulfate-polyacrylamide gel electrophoresis by using MAbs and polyclonal antisera to HRSV and BRSV. Shared epitopes were demonstrated on four of five structural proteins between BRSV and both subgroups A and B of HRSV. The nine isolates of BRSV showed different patterns of reactivity in enzyme immunoassays with panels of MAbs to HRSV subgroups A and B. Major variations in the molecular weights of the P (phosphoprotein) and F (fusion protein) proteins were demonstrated among the BRSV isolates tested. These results suggest that BRSV belongs to a different antigenic grouping than HRSV and that BRSV is composed of two distinct subgroups.
Characteristics and outcome variables of HIV cases at a university-based medical practice.
An increasing number of AIDS cases occur each year in West Virginia despite its small urban population. From January 1984 to March 1991 at the Marshall University based multispecialty internal medicine group (the University Physicians in Internal Medicine), 66 HIV-infected persons were treated, most of whom are native West Virginians and always resided in the state. The study group consisted of 61 men and 5 women; four-fifths of the men are homosexual/bisexual and one-seventh used intravenous illicit drugs. Four women acquired infection heterosexually and one from transfusion. Twenty-eight patients never had any opportunistic infection (OI) and 38 experienced at least one OI, usually Pneumocystis carinii Pneumonia. About two-fifths of patients had CD4 counts less than 200 cells/cmm at their initial examination. Three-fourths of patients received AZT, six ddI, and most aerosolized pentamidine. Nineteen patients have died, all of whom suffered at least one OI. The mean interval until death from HIV infection and from AIDS was about 27 and 11.5 months, respectively.
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.
A single-season epidemic with respiratory syncytial virus subgroup B2 during 10 epidemic years, 1978 to 1988.
Respiratory syncytial virus strains isolated from infants and children hospitalized with acute respiratory tract disease in Huntington, W. Va., from July 1979 through June 1988 were categorized by subgroup by using two panels of monoclonal antibodies specific for subgroup A and subgroup B. Of 405 strains tested, 319 (78.8%) were subgroup A, 73 (18.0%) were subgroup B1, and 13 (3.2%) were subgroup B2. The subgroup B2 strains occurred as a single-season epidemic during the epidemiologic year July 1980 to June 1981, except for one strain isolated in the epidemiologic year 1978 to 1979. Subgroup B strains were associated with significantly fewer bronchiolitis illnesses than subgroup A strains. The severity of illnesses caused by subgroup B1 and B2 strains was the same.
Genetic diversity of the attachment protein of subgroup B respiratory syncytial viruses.
Respiratory syncytial (RS) virus causes repeated infections throughout life. Between the two main antigenic subgroups of RS virus, there is antigenic variation in the attachment protein G. The antigenic differences between the subgroups appear to play a role in allowing repeated infections to occur. Antigenic differences also occur within subgroups; however, neither the extent of these differences nor their contributions to repeat infections are known. We report a molecular analysis of the extent of diversity within the subgroup B RS virus attachment protein genes of viruses isolated from children over a 30-year period. Amino acid sequence differences as high as 12% were observed in the ectodomains of the G proteins among the isolates, whereas the cytoplasmic and transmembrane domains were highly conserved. The changes in the G-protein ectodomain were localized to two areas on either side of a highly conserved region surrounding four cysteine residues. Strikingly, single-amino-acid coding changes generated by substitution mutations were not the only means by which change occurred. Changes also occurred by (i) substitutions that changed the available termination codons, resulting in proteins of various lengths, and (ii) a mutation introduced by a single nucleotide deletion and subsequent nucleotide insertion, which caused a shift in the open reading frame of the protein in comparison to the other G genes analyzed. Fifty-one percent of the G-gene nucleotide changes observed among the isolates resulted in amino acid coding changes in the G protein, indicating a selective pressure for change. Maximum-parsimony analysis demonstrated that distinct evolutionary lineages existed. These data show that sequence diversity exists among the G proteins within the subgroup B RS viruses, and this diversity may be important in the immunobiology of the RS viruses.
A subgroup-specific antigenic site in the G protein of respiratory syncytial virus forms a disulfide-bonded loop.
An antigenic site (represented by 15 amino acids, residues 174 to 188, designated peptide 12) of the large glycoprotein G of respiratory syncytial virus was demonstrated to be subgroup specific in peptide enzyme-linked immunosorbent assay tests with murine monoclonal antibodies and human postinfection sera. The role of individual amino acids in this subgroup-specific site was determined by use of single-amino-acid-deletion sets of peptides. When monoclonal antibodies were reacted with the deletion sets, a broad amino acid dependence of 11 or 12 residues, Cys-176 (Ile-175 in subgroup B) to Cys-186, was found. Human postinfection sera exhibited a narrower reaction profile (for subgroup A, Cys-182 to Trp-183; for subgroup B, Cys-176 to Lys-183). Reduction of peptides on microtiter plates by treatment with dithiothreitol completely destroyed their antigenic activity in tests with monoclonal antibodies and human postinfection sera of subgroup B. A variant of peptide 12 containing all four cysteines of the G protein (represented by 16 amino acids, residues 172 to 187, designated peptide 12var) also was subgroup specific. We concluded that the activity of the antigenic site in tests with monoclonal antibodies for subgroups A and B appears to depend on intrapeptide disulfide bonds. Reactions with postinfection sera of subgroup B also may depend on a disulfide bond. In contrast, postinfection sera of subgroup A appeared to have the capacity to identify a subgroup-specific site in a linear form of the selected 15-amino-acid-long peptide. Treatment of peptides with dithiothreitol had no effect on their antigenic activity in tests with human postinfection sera of subgroup A. These findings have relevance for molecular engineering of peptide antigens for use in respiratory syncytial virus subgroup-specific site-directed serology.
Occurrence, characteristics, and patterns of HIV-1 and HIV-2 western blot indeterminate sera in low risk populations in West Virginia and pre-AIDS Africa.
To further characterize HIV-1 and HIV-2 Western blot indeterminate (IWB) sera, 402 sera from 318 healthy low-risk individuals from West Virginia and 159 African sera obtained in the pre-AIDS era (1968-1972) were studied. All IWB sera tested for antigen by HIV-1 enzyme immunoassay (EIA-Ag) were negative. HIV-1 and HIV-2 IWB reactivity occurred independent of HIV-1 and HIV-2 false-positive testing for antibody by enzyme immunoassay (EIA-Ab) and no cross-reactions between HIV-1 and HIV-2 IWB patterns were detected. The IWB patterns were reproducible, demonstrated no age or sex related pattern, and showed no evidence of vertical or horizontal transmission. The African sera exhibited a significantly higher number of IWB patterns. IWB reactivity in HIV-1 and HIV-2 seronegative individuals may not be viral in origin and the occurrence of IWB pattern may vary among populations.
The immunobiology of respiratory syncytial virus: prospects for a vaccine.
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Respiratory syncytial virus epidemics: variable dominance of subgroups A and B strains among children, 1981-1986.
We examined the distribution of subgroups A and B strains from respiratory syncytial virus during five epidemic years from 1981 to 1986 in Huntington, West Virginia. Of 235 infants and children with respiratory syncytial virus infection, 211 had virus reisolated from frozen throat swab specimens for subgroup characterization by reactivity with a panel of monoclonal antibodies to the G, F, NP, M, and P proteins by using an enzyme immunoassay. We identified 160 (75.8%) strains as subgroup A and 51 (24.2%) as subgroup B. Strains of both subgroups were isolated in all years. Small, but approximately equal, numbers of subgroup B strains were isolated each epidemic year. By contrast, subgroup A strains occurred at least three times as often in all years except 1984-1985. The very low number of subgroup A strains isolated during the 1984-1985 epidemic gave dominance to subgroup B strains.
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.
Modern diagnostic methods of viral infections and their treatment.
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Site-directed serology with synthetic peptides representing the large glycoprotein G of respiratory syncytial virus.
A set of 23 nested 15-amino-acid-long peptides with overlaps of 5 amino acids, representing the complete extramembranous part of the large glycoprotein G of respiratory syncytial (RS) virus, was analyzed in ELISA against different sera containing virus-specific antibodies. Seven of the peptides reacted with rabbit hyperimmune sera against purified virions. In contrast, only one of these seven peptides reacted with murine monoclonal antibodies specific for G. In connection with RS virus infections in humans, increase of antibody titers against three peptides was found in about one-third of the cases. These three peptides were included among those identified by both murine and rabbit antibodies. The present findings may open possibilities for site-directed clinical serology in the case of RS virus infections.