Concurrent circulation of antigenically distinct strains of respiratory syncytial virus during community outbreaks

Respiratory syncytial virus (RSV) is considered to be of a single serotype. Antigenic variants are detectable both by neutralization and monoclonal antibodies and have been divided into two broad categories, groups 1 and 2. Group 2 isolates have been considered to be uncommon. We used indirect immunofluorescence with strain-specific monoclonal antibodies to study RSV isolates from hospitalized infants in the greater Boston area. Of 223 RSV isolates recovered over a five-month period in 1983-1984, 125 (56%) were group 1, 92 (41%) were group 2, and 6 (3%) were of an intermediate character. Among 181 community-acquired RSV isolates, both temporal and geographic clustering was observed: group 1 isolates were common from January through March and predominated in central Boston; group 2 isolates were found principally in February and were acquired in outlying, particularly northern, areas. Strain-specific differences were not found with respect to sex, age, or clinical findings. An analysis of 82 RSV isolates from the 1981-1982 season showed 75 (91%) group 1 isolates and 7 (9%) group 2 isolates. We conclude that at least two antigenically distinct groups of RSV isolates may circulate concurrently in the community and that the prevalence of group 2 isolates appears greater than previously suspected.     

Clinical characteristics of respiratory syncytial virus (RSV) subgroup infections in Japan.

The subgroup characteristics of 130 strains of respiratory syncytial virus (RSV) isolated in Sapporo during 9 epidemic years 1980-1989 were determined. Monoclonal antibodies raised against the RSV Long strains were used. Subgroup A included 77 (59.2%) isolates and subgroup B 52 (40.0%) strains, while 1 strain was considered to be a variant of a subgroup A strain. The distribution by age of infants and children was different for the 2 subgroups: less than 1 year of age infants with subgroup A infection dominated, greater than 1 year of age subgroup A infections were less common than subgroup B infections. These was no difference in type of illness between the subgroups. Bronchiolitis was the dominant diagnosis in all patients.     

Antigenic and genomic diversity within group A respiratory syncytial virus

Antigenic analysis using monoclonal antibodies and genomic analysis using ribonuclease protection was done on 47 isolates of group A respiratory syncytial virus (RSV) recovered from children in St. Louis during four RSV seasons. Antigenic analysis identified four subgroups; of the three that included more than one member, those designated A/2 and A/2V had characteristic ribonuclease protection patterns. A third subgroup, A/4, exhibited more extensive genomic heterogeneity, but all isolates were distinguishable from those in subgroups A/2 and A/2V. Individual RSV epidemic seasons included isolates representing multiple subgroups of group A and multiple intrasubgroup variants, in addition to isolates from group B. Isolates that were indistinguishable by either antigenic or genomic analysis were present in more than one epidemic season. The subgroups may represent parallel evolutionary lineages, whose relevance to RSV immunity and pathogenesis requires further study.     

Multicenter study of strains of respiratory syncytial virus

Two major groups of respiratory syncytial virus (RSV) strains, A and B, have been identified and their patterns of isolation determined in different communities but not simultaneously in multiple communities. In this study, we tested 483 RSV isolates from 14 university laboratories in the United States and Canada for the 1984/1985 and 1985/1986 RSV seasons; 303 (63%) isolates were group A, 114 (24%) were group B, and 66 (14%) could not be grouped. Isolates were subdivided into six subgroups within group A and three within group B; up to six and often four or more different subgroups were isolated in the same laboratory during the same RSV season. The pattern of group and subgroup isolations varied among laboratories during the same year and between years for the same laboratory. These differences suggest that RSV outbreaks are community, possibly regional, but not national phenomena. The ability to identify group and subgroup differences in isolates is a powerful tool for epidemiologic studies of RSV.     

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 in a community population: circulation of subgroups A and B since 1965

Respiratory syncytial viruses were isolated from residents of Tecumseh, MI, with illnesses of all severities during the periods 1965-1971 and 1976-1981. These isolates were grouped using one monoclonal antibody specific for each subgroup. All were identified as either subgroup A or B. Subgroup A predominated in most years. No differences in age distribution or illness characteristics could be found between the subgroups. This study demonstrated that the currently recognized subgroups have been present in a single community since 1965, and their behavior in the past is similar to that currently described.     

Occurrence of groups A and B of respiratory syncytial virus over 15 years: associated epidemiologic and clinical characteristics in hospitalized and ambulatory children

Over 15 years respiratory syncytial virus (RSV) isolates from 1209 hospitalized and ambulatory children were examined for strain group and in a subset for subgroup to determine the associated epidemiologic and clinical characteristics. Three patterns of yearly outbreaks existed: (1) strong predominance of group A strains (9 years with 83%-100% A strains), (2) relatively equal proportions of group A and B strains (4 years), and (3) strong predominance of group B strains (78%-85%) in 2 years, separated by a decade. The first pattern of highly dominant A strains occurred in cycles of 1 or 2 consecutive years with a single intervening year in which B strains were greater than or equal to 40% of the isolates. Subgroups A1 and A2 predominated, while B2, 3, and 4 occurred almost equally. A greater clinical severity for Group A strains was suggested by children with group A infections requiring intensive care significantly more often (15.4 vs. 8.3%, P = .008). Further, strongly dominant A strain years were associated with higher proportions of RSV admissions requiring intensive care (16.6% vs. 5.5%, P less than .01). Strains of subgroups A2 and B4 were more frequently found in hospitalized patients and A1 in outpatients, and the 2 years with the highest rates of intensive care admissions were those in which subgroup A2 dominated.     

Human monoclonal Fab fragments derived from a combinatorial library bind to respiratory syncytial virus F glycoprotein and neutralize infectivity.

Respiratory syncytial virus (RSV) is the most important cause, throughout the world, of severe viral lower respiratory tract illness in young children. Antibodies are known to mediate resistance to RSV infection and illness. We have isolated a number of human monoclonal Fab fragments to RSV F glycoprotein from a combinatorial antibody library expressed on the surface of phage. One of these neutralized a wide range of virus isolates, 10 subgroup A and 9 subgroup B isolates, with a titer (60% neutralization) of approximately 0.1-1.0 micrograms/ml. Another Fab neutralized diverse isolates at a concentration somewhat higher. These human Fab fragments show great promise for use in the prophylaxis or therapy of serious RSV lower respiratory tract disease. For intramuscular or intravenous administration, whole antibodies will be required, whereas for aerosol application, F(ab')2 or Fab fragments may suffice.     

Association between respiratory syncytial virus outbreaks and lower respiratory tract deaths of infants and young children

The temporal patterns of respiratory virus isolations from 10 laboratories in the USA were compared with that of deaths of children less than 5 years old from July 1975 through June 1984. Isolations of respiratory syncytial virus (RSV) occurred as yearly winter outbreaks; parainfluenza virus 1 and 2 isolations occurred as well-defined outbreaks every other year in the autumn; parainfluenza virus 3 isolations occurred throughout the year with periodic, increased isolations suggestive of outbreaks; and influenza virus isolations (A, B, or A plus B) occurred as yearly winter outbreaks. After data were controlled for seasonal patterns, RSV isolations were strongly correlated with the winter peaks in lower respiratory tract illness (LRI) deaths of infants 1-11 months old; influenza virus isolations were correlated with the winter peak in LRI deaths of children 24-59 months old. The parainfluenza viruses were not correlated with respiratory deaths. This study supports the idea that RSV is a major contributor to winter peaks in LRI deaths of children 1-11 months old.     

Correlation between respiratory syncytial virus genotype and severity of illness

Respiratory syncytial virus (RSV) causes seasonal outbreaks of respiratory tract infections, but the viral factors associated with virulence remain unknown. To determine whether RSV genotype correlated with severity of illness, isolates were characterized by phylogenetic analysis of the RSV G gene, and a composite score was used to quantify severity of illness. During the 1998-1999 and 1999-2000 winter seasons, 137 subgroup A and 84 subgroup B isolates were identified. The severity of illness caused by subgroup A isolates did not differ from that caused by subgroup B isolates (P=.086). However, the GA3 clade was associated with significantly greater severity of illness, compared with clades GA2 (P=.004) and GA4 (P=.016). In a subpopulation of patients < or =24 months old who had no known risk factors for severe RSV disease, clade GA3 was again associated with greater severity of illness, compared with clade GA2 (P=.018). Severity of RSV infection is associated with RSV genotype.     

Pediatric RSV infection during two winter seasons in British Columbia: A role for subgroup analysis in young children?

Using a panel of eight monoclonal antibodies directed against the G, F and NP proteins of respiratory syncytial virus, 167 virus isolates from nasopharyngeal washing cultures at British Columbia Children's Hospital during two consecutive epidemics were subgrouped. Slides made and frozen at the time of virus isolation or prepared from recovered frozen passage material, were assayed by indirect immunofluorescence. Of 85 strains tested in 1987-88, 54 (64%) were subgroup A, and 31 (36%) subgroup B. By contrast, of 82 strains tested in 1988-89 five (6%) were subgroup A and 77 (94%) subgroup B. Review of patient charts did not reveal significant differences in clinical course of patients infected with the two subgroups, but the risk of infection with subgroup A was significantly greater than the risk of subgroup B infection in younger patients.     

The G glycoprotein of human respiratory syncytial viruses of subgroups A and B: extensive sequence divergence between antigenically related proteins.

Two major antigenic subgroups (designated A and B) have been described for human respiratory syncytial virus (RSV). Previously, on the basis of reactivity patterns with monoclonal antibodies, the greatest intersubgroup variation was shown to occur in the G protein, the putative attachment glycoprotein. To delineate the molecular basis for this variation, we have determined the nucleotide and deduced amino acid sequences of the G mRNAs and proteins representing a subgroup A (Long strain) and a subgroup B (18537 strain) virus. These sequences were compared to the available G mRNA sequence for another subgroup A (A2 strain) virus. The Long G protein shared 94% amino acid identity with the A2 G protein. In contrast, the 18537 G protein shared only 53% amino acid identity with the A2 sequence; interestingly, most of the sequence divergence occurred in the proposed extracellular domain of the G protein. This extensive divergence for the G protein was significantly greater than that observed for other RSV proteins. Despite this considerable divarication, the proposed extracellular domains of the G proteins contained a single region of highly conserved sequence and secondary structure that may represent a conserved structural or function domain, perhaps involved in attachment to cellular receptors. Furthermore, this conserved region may comprise part of an epitope that is shared between the two subgroup G proteins and may significantly contribute to the fact that, despite extensive overall amino acid sequence divergence, the RSV G proteins maintain significant antigenic relatedness.     

Respiratory syncytial virus infection

Human respiratory syncytial virus (RSV) is the most common worldwide cause of lower respiratory tract infections (LRI) in infants less than 12 months of age. RSV isolates can be divided into group A and B. In addition, there were many genotypes within each group, and these genotypes have evolved global setting with temporal and geographic clustering. Many cellular genes encoding cytokines and chemokines which are activated by RSV infection has now been focused for the elucidation of pathophysiology of RSV LRI. The prophylaxis against RSV infection by vaccination has been unsuccessful because of its adverse effects. No valuable anti-RSV drugs for clinical use have been yet developed. Therefore RSV LRI has been treated mainly symptomatically. Recently humanized anti-RSV F protein monoclonal antibody was developed and prescribed for prevention in high-risk infants such as premature ones and those with chronic lung and congenital heart diseases. It reduced the incidence of hospitalization significantly.     

Genetic variation and evolution of human parainfluenza virus type 1 hemagglutinin neuraminidase: analysis of 12 clinical isolates.

The extent of genetic variation and evolution in a population of human parainfluenza virus type 1 was investigated. The hemagglutinin neuraminidase genes of 13 isolates collected over a 26-year period were sequenced and compared. All isolates except the 1957 type strain were from a single geographic location and demonstrated significant consistent genetic change from the type strain (47/7 [nucleotide/amino acid] substitutions). Antigenic subgroup A isolates demonstrated minor intragroup differences (9/1 substitutions). However, 18/7 unique substitutions separated subgroup A from B regardless of geographic location or year of isolation. Multiple strains of both subgroups appeared and reappeared over decades with only minor variation. There may be significant genetic differences between clinical isolates based on geographic location, and progressive mutational change may occur. Previously defined antigenic and now genetic subgroups were stable and at least regional in distribution over the period studied. The biologic implications and extent of this variation need further evaluation.     

Survey of human rotavirus serotypes in different locales in Japan by enzyme-linked immunosorbent assay with monoclonal antibodies

To investigate the relative frequency of individual human rotavirus serotypes prevailing in Japan, 562 stool specimens collected from patients with rotavirus gastroenteritis between November 1986 and March 1988 in seven districts were examined by an enzyme-linked immunosorbent assay (ELISA) with serotype 1-, 2-, 3-, and 4-specific monoclonal antibodies. Serotype 1 was the predominant serotype in the winter of 1986-1987; however, both serotypes 1 and 2 were detected frequently in the winter of 1987-1988. The results showed the relative frequency of individual serotypes by locale and the yearly change in the prevalence of each serotype in the same area. The result of subgroup specificity of rotavirus obtained by using ELISA with subgroup I- and II-specific monoclonal antibodies confirmed the general finding that rotavirus strains having subgroup I specificity are serotype 2 and those having subgroup II specificity are either serotype 1, 3, or 4. Unusual strains having both subgroup I and II specificity or neither specificity and strains presumed to represent new serotypes were also found.     

Autoimmune thyroid disease in systemic lupus erythematosus

BACKGROUND: The reported prevalence of autoimmune thyroid disease (3.9-24%) and antithyroid antibodies (11-51%) in SLE varies considerably. Early reports were mainly based on short term studies of small cohorts. OBJECTIVE: To report the prevalence of autoimmune thyroid disease and thyroid antibodies in 300 patients with SLE, followed up at our centre between 1978 and 2000, by a retrospective analysis of case notes. RESULTS: The prevalence (5.7%) of hypothyroidism in our cohort was higher than in the normal population (1%), while that of hyperthyroidism (1.7%) was not significantly different. Overall 42/300 (14%) of our cohort had thyroid antibodies, rising to 15/22 (68%) in the subgroup who also had thyroid disease (p<0.001). Both antimicrosomal and antithyroglobulin antibodies were detected. The antibodies were found in equally high frequency in the hyperthyroid subgroup (80% patients), whereas in the hypothyroid subgroup antimicrosomal antibodies were more frequent than antithyroglobulin antibodies (64% v 41%). There was no significant difference in the frequency with which antimicrosomal or antithyroglobulin antibodies were detected between the hyperthyroid and hypothyroid subgroups (p>0.2). CONCLUSION: Our patients with SLE had a prevalence of hypothyroidism, but not hyperthyroidism, greater than that of the normal population. The presence of either condition was associated with a higher frequency of both antimicrosomal and antithyroglobulin antibodies.     

Surveillance of clinical isolates of respiratory syncytial virus for palivizumab (Synagis)-resistant mutants

Premature infants and those with chronic lung disease or congenital heart disease are at high risk of severe respiratory syncytial virus (RSV) disease. Palivizumab (Synagis), a humanized anti-RSV monoclonal antibody, has been used extensively since 1998 to prevent severe RSV disease in high-risk infants. To monitor for possible palivizumab-resistant mutants, an immunofluorescence binding assay that predicts palivizumab neutralization of RSV was developed. RSV isolates were collected at 8 US sites from 458 infants hospitalized for RSV disease (1998-2002). Palivizumab bound to all 371 RSV isolates able to be evaluated, including 25 from active-palivizumab recipients. The palivizumab epitope appears to be highly conserved, even in infants receiving prophylaxis with palivizumab.     

Polymorphism of normal factor IX detected by mouse monoclonal antibodies.

Hemophilia B is an X-chromosomal recessive disease due to deficiency of coagulation factor IX. Three monoclonal antibodies against factor IX were prepared and used to develop immunoradiometric assays (IRMAs) of factor IX antigen (IX-Ag). IX-Ag was measured in 65 normal individuals with one IRMA based on polyclonal anti-IX antibodies and two IRMAs based on three monoclonal anti-IX antibodies. One of the monoclonal antibodies differed in specificity since it neutralized less than 50% of the clotting activity of factor IX (IX-C), whereas the other two monoclonal antibodies neutralized 80-95%. When the former antibody was used as the solid phase in IRMA, two groups of normal individuals were distinguished: group A with measurable IX-Ag, and group B without demonstrable IX-Ag. There were no differences between the groups either in IX-C or in IX-Ag measured with polyclonal antibodies. A subgroup comprising only women could be distinguished in group A, in whom intermediate IX-Ag concentrations were found. Family studies showed the group B variant of normal factor IX to be transmitted according to the pattern of X-linked recessive inheritance. The allelic frequency of group A was 0.66, and that of group B was 0.34.