Serum and nasal-wash immunoglobulin G and A antibody response of infants and children to respiratory syncytial virus F and G glycoproteins following primary infection.

An enzyme-linked immunosorbent assay (ELISA) with immunoaffinity-purified fusion (F) or attachment (G) glycoprotein was used to measure the serum and secretory immune responses of 18 infants and children, 4 to 21 months of age, who underwent primary infection with respiratory syncytial virus (RSV). Most of the 10 older individuals (9 to 21 months of age) developed moderate levels of serum and nasal-wash immunoglobin A (IgA) and IgG F and G antibodies. These individuals developed a moderate level of serum or nasal-wash antibodies that neutralized virus infectivity. One of the eight younger individuals (4 to 8 months of age) failed to develop an F antibody response, while three failed to develop a G antibody response. The most notable difference in the responses of the two age groups involved the titer in convalescent sera of G, F, and neutralizing antibodies which were 8- to 10-fold lower in younger individuals. Most of the younger infants failed to develop a rise in serum or nasal-wash neutralizing antibody. It is possible that the presence of maternally derived antibody in the younger infants suppressed the immune response to RSV infection, and that this accounted, in part, for the low level of postinfection antibody titer in this group. This low level and the irregular response of the infants less than 8 months of age may contribute to the severity of their initial infection and may also be responsible, in part, for their failure to develop effective resistance to subsequent reinfection by RSV.     

Serum immunoglobulin G antibody subclass responses to respiratory syncytial virus F and G glycoproteins after primary infection

Because the immunoglobulin G (IgG) response to carbohydrate antigens is typically from the IgG2 subclass and the IgG response to protein antigens is typically from the IgG1 and sometimes the IgG3 subclass, two respiratory syncytial virus glycoproteins, F and G, which differ substantially in the amount of glycosylation, were used as antigens in an enzyme-linked immunosorbent assay to determine IgG subclass responses in 20 infants and young children with naturally acquired respiratory syncytial virus infection. Both glycoproteins elicited primarily IgG1 and IgG3 responses, indicating that the protein moieties of the glycoproteins may be immunodominant in this age group.     

Relation of serum antibody to glycoproteins of respiratory syncytial virus with immunity to infection in children

Immunity in relation to passively transferred maternal and naturally-induced serum antibody to the viral proteins was determined in 34 children who were followed from birth through three years of age for respiratory syncytial virus infection (RSV). Sera were tested by immunoglobulin class-specific enzyme-linked immunosorbent assay using the attachment and fusion proteins of the Long strain. The basis for immunity for maternal antibody in primary infection was assessed by a comparison of the distribution of antibody titers in a) 7 children who had an upper respiratory illness to 12 whose illness was accompanied by lower respiratory disease and of b) 13 children with an RSV-associated illness in the first 6 months of life who were age-matched as to month and approximate day of birth with 11 not infected in the same period. Infection induced immunity was evaluated by a comparison of antibody titers in 19 children who were reinfected with RSV in the year following their primary infection to 15 in whom reinfection was not documented. A statistical analysis of titers revealed that antibody to the fusion protein is an important correlate of immunity. In all three comparisons, the children with less RSV disease had significantly higher IgG anti-F titers prior to infection. No differences were observed between IgA anti-F or IgG and IgA anti-G titers.     

Differential immunoglobulin G subclass antibody titers to respiratory syncytial virus F and G glycoproteins in adults

Two respiratory syncytial virus glycoproteins, F and G, which differ substantially in the amount of glycosylation were used as antigens in an enzyme-linked immunosorbent assay to determine immunoglobulin G (IgG) subclass titers in 30 experimentally infected healthy adults. The titers of antibodies to the F glycoprotein achieved in postinfection sera were highest in the IgG1 subclass, whereas those to the G glycoprotein were highest and comparable in the IgG1 and IgG2 subclasses. The high IgG2 response to the G glycoprotein suggests that it is seen by the immune system as a polysaccharide antigen, a hypothesis consistent with its large carbohydrate content.     

Serum immunoglobulin G antibody subclass response to respiratory syncytial virus F and G glycoproteins after first, second, and third infections

Serum samples from 31 children who experienced two or three infections with respiratory syncytial virus (RSV) in the first four years of life were tested in an enzyme-linked immunosorbent assay to examine the immunoglobulin G (IgG) subclass responses to the RSV F and G surface glycoproteins associated with primary infection and reinfection. We sought to determine whether the greater degree of glycosylation of the G glycoprotein was reflected in an IgG subclass immune response more like that to a polysaccharide antigen than to a protein antigen. We found that the IgG1/IgG2 ratio of postinfection antibody titers to F was fourfold higher than that to the G glycoprotein after RSV infections 1, 2, and 3. The IgG2 response to the heavily glycosylated G glycoprotein differed from that to a polysaccharide antigen in that the IgG1/IgG2 ratio remained constant with age, whereas the response to a polysaccharide antigen decreased as the IgG2 response increased with age. We also noted that antibody responses to both surface glycoproteins in the IgG1 and IgG2 subclasses reached their maximum levels after RSV infection 2.     

Interprotein disulfide bonding between F and G glycoproteins of human respiratory syncytial virus

The envelope glycoprotein G, of human respiratory virus was purified by immunoaffinity chromatography using a monoclonal antibody reacting with G glycoprotein. The purified material was analyzed for its protein patterns and by western blot for its reactivity with specific monoclonal antibodies. In addition to the G specific proteins at 90 and 55 kilodalton (kDa) range, high molecular weight species were coeluted with G protein. Three high molecular weight species were noticed: one (140 kDa) reacting with fusion protein (F) monoclonal antibody and two other species (230 and 195 kDa) reacting with both fusion protein and G protein monoclonal antibodies. The protein reacting only with F monoclonal antibody consists of fusion protein dimer. Western blot and two dimensional gel electrophoretic analysis revealed that each of the other two complexes is composed of two moles of F protein and one mole of G protein. These two complexes differ in their molecular sizes depending on whether G is in the form of 90 or 55 kDa. Upon heat denaturation, fusion protein monomer (70 kDa) is released from the complex, leaving the two complexes, consisting of one mole of F protein and one mole of G protein (160 and 125 kDa species respectively). Disulfide-reducing agents are required to break the monomers of F and G complexes. These results provide a direct evidence for the presence of envelope glycoprotein complexes linked by interprotein disulfide bonding. This may have implications on the structural and functional properties of envelope glycoproteins.     

Immunoglobulin G antibody avidity in patients with respiratory syncytial virus infection.

The titer and avidity of respiratory syncytial virus-specific antibodies were measured in 196 serum specimens from 93 children with an acute, laboratory-confirmed respiratory syncytial virus infection. An enzyme immunoassay method based on the ability of urea to dissociate the bound antibodies with low avidity from the antigen was used. Three patterns of immune responses were observed. Children less than 6 months of age usually had low titers of antibodies with high avidity in their acute-phase serum samples. These antibodies were concluded to be of maternal origin, since their reaction pattern was similar to that of healthy adults. During the next few weeks, a slight increase in titers with a concurrent decrease in antibody avidity was observed. All children 6 to 24 months of age had low-avidity antibodies in their acute-phase serum samples, which matured to high avidity during the follow-up. On the contrary, about half of the children greater than 24 months of age had high-avidity antibodies already in the acute-phase serum samples. We conclude that the former children were experiencing primary infections with respiratory syncytial virus and the latter were experiencing reinfections. All adults with remote immunity had antibodies with high avidity.     

Detection of antibody to bovine syncytial virus and respiratory syncytial virus in bovine fetal serum.

Batches of commercial fetal bovine serum, described by the suppliers as antibody-free, all contained antibody to bovine syncytial virus (BSV) when tested by indirect immunofluorescence. Antibody to bovine respiratory syncytial virus (RSV) was not detected in these sera. Twenty-four percent of individual fetal bovine sera contained antibody to BSV, and 14% contained antibody to RSV when tested by indirect immunofluorescence. BSV antibody titers in fetal sera from dams with high BSV antibody levels were variable but always higher than RSV antibody titers. Radial immunodiffusion studies with BSV-positive sera revealed the presence of immunoglobulin M (IgM), IgG, and IgA, but the quantity of these immunoglobulins was not directly related to the BSV antibody titers. The evidence suggests that the antibody present in fetal sera arose as the result of infection rather than from maternal transfer across the placenta.     

Respiratory syncytial virus group-specific antibody response in nasopharyngeal secretions from infants and children after primary infection.

Respiratory syncytial virus (RSV) group-specific immunoglobulin A (IgA) and IgG enzyme-linked immunosorbent assay antibody and neutralizing antibody responses were determined for nasopharyngeal secretions (NPS) from 27 infants and children (6 to 18 months of age) undergoing primary infection with RSV group A or B strain. IgA and IgG antibody responses against RSV envelope glycoproteins (fusion [F] and large [G] glycoprotein) in NPS were also analyzed. Most subjects examined developed moderate levels of NPS IgA and IgG antibodies and neutralizing antibody activity to both group A and B strains in convalescent phase; however, the levels of antibodies to homologous strains were significantly higher than to the heterologous strains. Patients infected with group A developed antibodies in both F and G glycoproteins of A2 strains (group A). Patients infected with group B developed levels of antibody activity to F glycoprotein of A2 strain similar to those of patients infected with group A. However, these subjects developed little or no antibody response to G glycoprotein of A2 strain. These data suggest that the IgA and IgG antibody responses to G glycoprotein in the respiratory tract are group specific. It is suggested that lack of antibody response to the G glycoprotein of the heterologous group in the respiratory tract may determine the outcome of reinfection with other RSV strains.     

Human respiratory syncytial virus surface glycoproteins F, G and SH form an oligomeric complex

Summary.  In order to study structural associations, RSV surface glycoproteins were evaluated using heparin agarose affinity chromatography (HAAC). When RSV-infected cell lysate was analyzed by HAAC, all three surface glycoproteins, (F, G and SH), were eluted. Similarly, when separate lysates from Vero cells infected with vaccinia recombinants expressing F (vvF), G (vvG) and SH (vvSH) proteins were subjected to HAAC, only vvF and vvG expressed proteins bound to heparin, whereas vvSH expressed protein did not bind. When lysates from vvF, vvG and vvSH-infected Vero cells were mixed prior to HAAC, only F and G bound heparin. In contrast, following co-infection of Vero cells with vvF, vvG and vvSH, all three proteins were detected subsequent to HAAC. Following HAAC of A2-infected cell lysate and lysate from vvF, vvG and vvSH co-infected Vero cells, two high molecular weight complexes of 175 Kd and 210 Kd, respectively, were identified that reacted with anti-F, anti-G and anti-SH antisera. In addition, anti-SH antiserum was able to co-precipitate RSV F, G and SH. Using HAAC and a NaCl step gradient we demonstrated that a fraction of RSV F, G and SH eluted at higher salt concentrations than either purified F or G protein. Taken together, these data suggest that RSV F, G and SH glycoproteins can form an oligomeric complex within infected cells and this complex has a higher affinity for heparin than either G or F protein alone. Received April 6, 2001 Accepted June 4, 2001     

Cell-free and cell-bound antibody in nasal secretions from infants with respiratory syncytial virus infection.

Twenty-two infants under 9 months of age hospitalized with bronchiolitis or pneumonia due to respiratory syncytial virus (RSV) were serially sampled to determine the pattern of secretory antibody response. Using double labeling techniques, we found several types of immunoglobulin in secretions: cell-free antibody to RSV of the immunoglobulin A (IgA), immunoglobulin G (IgG), and immunoglobulin M (IgM) classes; and immunoglobulins of all three classes bound to RSV-infected cells shed from the nasal epithelium (presumably cell-bound antibody to RSV). IgA attached to RSV-infected epithelial cells was almost always detected in the first available nasal sample (day 1 or 2 of hospitalization). In contrast, cell-free anti-RSV IgA first appeared an average of 3.5 days later at a time when virus antigen was disappearing from the secretion. IgG and IgM attached to RSV-infected cells appeared more irregularly. The titer of cell-free anti-RSV IgM was often higher than that of IgA early in the illness and declined as the infection resolved. Cell-free anti-RSV IgG was usually present earlier than IgA and rose during convalescence.     

北京地区正常人群血清中呼吸道合胞病毒F和G蛋白特异性IgG抗体水平的观察

以表达呼吸道合胞病毒（ＲＳＶ）Ｆ和Ｇ蛋白的重组痘苗病毒作为抗原，用间接免疫荧光法检测北京地区不同年龄组正常儿童及成人血清中ＲＳＶＦ和Ｇ蛋白特异性ＩｇＧ抗体。其结果表明：成人及产妇静脉血中有中等滴度的ＲＳＶ抗体及较低水平的Ｆ和Ｇ蛋白特异性ＩｇＧ抗体。初生婴儿脐带血中的ＲＳＶＦ和Ｇ蛋白ＩｇＧ抗体水平同母亲静脉血中的一致，表明属母传抗体。婴幼儿ＲＳＶ抗体水平在生后６个月内迅速降低，６个月以后抗体的滴度随年龄消长，７－１４岁时水平最高。Ｆ和Ｇ蛋白特异性ＩｇＧ抗体滴度在生后６个月内无明显降低，但低于大年龄组儿童。６个月后Ｆ和Ｇ蛋白抗体滴度显著升高并随年龄波动，Ｆ较Ｇ蛋白更为显著，分别在３～７岁（Ｆ蛋白）和７－１４岁（Ｇ蛋白）组中达是高滴度。从ＲＳＶ，Ｆ和Ｇ蛋白三种特异性ＩｇＧ抗体间的相关性来看：ＲＳＶ分别同Ｆ和Ｇ蛋白抗体呈现明显的相关性，但Ｆ和Ｇ蛋白特异性ＩｇＧ抗体间无明显相关性。     

Dissociation between serum neutralizing and glycoprotein antibody responses of infants and children who received inactivated respiratory syncytial virus vaccine.

The serum antibody response of infants and children immunized with Formalin-inactivated respiratory syncytial virus (RSV) vaccine 20 years ago was determined by using an enzyme-linked immunosorbent assay specific for the RSV fusion (F) and large (G) glycoproteins and a neutralization assay. Twenty-one young infants (2 to 6 months of age) developed a high titer of antibodies to the F glycoprotein but had a poor response to the G glycoprotein. Fifteen older individuals (7 to 40 months of age) developed titers of F and G antibodies comparable to those in children who were infected with RSV. However, both immunized infants and children developed a lower level of neutralizing antibodies than did individuals of comparable age with natural RSV infections. Thus, the treatment of RSV with Formalin appears to have altered the epitopes of the F or G glycoproteins or both that stimulate neutralizing antibodies, with the result that the immune response consisted largely of "nonfunctional" (i.e., nonneutralizing) antibodies. Subsequent natural infection of the vaccinees with wild-type RSV resulted in enhanced pulmonary disease. Despite this potentiation of illness, the infected vaccinees developed relatively poor G, F, and neutralizing antibody responses. Any or all of three factors may have contributed to the enhancement of disease in the RSV-infected vaccinees. First, nonfunctional antibodies induced by the inactivated RSV vaccine may have participated in a pulmonary Arthus reaction during RSV infection. Second, the poor antibody response of infants to the G glycoprotein present in the Formalin-inactivated vaccine may have been inadequate to provide effective resistance to subsequent wild-type virus infection. Third, the relatively reduced neutralizing antibody response of the infant vaccinees to wild-type RSV infection may have contributed to their enhanced disease by delaying the clearance of virus from their lungs.     

Local antibody production and respiratory syncytial virus infection in children with leukaemia

Children undergoing therapy for acute lymphoblastic leukaemia (ALL) are at increased risk of severe viral respiratory infection, and some find it difficult to terminate virus secretion. This increased severity may result from a defect in the mucosal immune response. To test this hypothesis, nasal immunoglobulin secretion and specific antiviral antibody responses to infection with respiratory syncytial (RS) virus in children with ALL have been compared with those in a normal age-matched comparison group. Children with leukaemia secreted normal levels of IgA and slightly raised IgM levels. IgG levels were depressed. Following RS virus infection, the majority of children with leukaemia secreted normal amounts of IgA and IgG nasal antibody and successfully cleared the virus. However, three of the 13 children studied made poor or undetectable nasal antibody responses, which correlated with their inability to clear the virus.     

Purification of respiratory syncytial virus F and G proteins

Respiratory syncytial virus (RSV) is the most important cause of severe lower respiratory tract infections of infants in industrial nations. In addition, the participation of RSV in the genesis of asthma is under discussion. The RSV glycoproteins F and G have key positions in the viral pathogenesis. At present no satisfactory protein purification protocols are available for these proteins. The methods published for the G protein using preparative SDS-PAGE or immunoaffinity chromatography yield only small amounts of purified G protein that has partially lost its antigenicity. We describe a three-step purification protocol for these glycoproteins. RSV-infected HEp-2 cells were lysed by a Triton X-100 containing buffer. The viral proteins were captured by QAE-Sephadex A-50 material in a batch procedure. A first elution with 100 mM NaCl led to a crude F protein fraction, and a second elution with 300 mM NaCl led to a crude G protein fraction. The F protein was further purified on a Lentil-lectin Sepharose 4B column and finally polished using a Resource Isopropyl column. Lentil-lectin Sepharose 4B was also used to purify the G protein from the crude fraction, but polishing of the G protein was carried out on a Resource Q column. Homogenous RSV-F and RSV-G proteins were obtained by this protein purification protocol. No loss of antigenicity could be observed during this procedure as the highly purified viral proteins remain detectable by a set of monoclonal antibodies and specific antisera. The G protein was isolated as a 90000 monomer, whereas the purified F protein was recovered as a functional homodimer of 140000.     

Pulmonary eosinophilic response to respiratory syncytial virus infection in mice sensitized to the major surface glycoprotein G.

To investigate the contribution of immunity to individual respiratory syncytial (RS) virus proteins to the augmentation of pulmonary pathology, mice were scarified with recombinant vaccinia viruses (rVV) expressing individual RS virus proteins. The pulmonary response to infection with RS virus was monitored by bronchoalveolar lavage (BAL). In mice vaccinated with the major surface glycoprotein (G), 14-25% of BAL cells were eosinophils; these comprised less than 3% of BAL cells from other groups of mice after RS virus challenge. Mice sensitized to the G or fusion (F) proteins developed lung haemorrhage and those sensitized to G, F or nucleoprotein (N) showed pulmonary polymorphonucleocyte efflux. To investigate the concomitant changes in local T-cell subsets, BAL cells were stained with mAbs to CD4, CD8, CD45RB, alpha beta and gamma delta T cell receptor (TCR) proteins. Three colour flow cytometry showed that most cells were CD3+CD4+ alpha beta+gamma delta+ or CD3+CD8+ alpha beta+gamma delta-, although some CD4-CD8-SIg- cells were also identified. Most of these 'null' cells lacked CD3, but CD3+ null cells from rVV-G or -F primed mice bore either alpha beta and gamma delta TCR in approximately equal numbers. The intensity of staining for CD45RB declined rapidly after infection with RS virus on both CD4 and CD8 cells. The rate of loss of CD45RB on CD4 T cells was accelerated by prior sensitization with rVV-G, consistent with conversion to helper T cell subsets producing eosinophil-promoting cytokines. The eosinophilic reaction to RS virus infection therefore specifically reflects sensitization to G protein, but sensitization to other proteins can also cause distinct pathological effects.(ABSTRACT TRUNCATED AT 250 WORDS)     

Maternal antibody and respiratory syncytial virus infection in infancy

One hundred newborn infants were studied prospectively for 1 year for evidence of infection with respiratory syncytial virus (RSV). The indirect membrane fluorescence technique was used to determine specific antibody in sera. Infection was shown in 29 cases. In 31 infants exposed to an RSV epidemic season, there was no evidence of infection. Maternal antenatal sera were also tested, and a wide range of IgG antibody to RSV was found. Mean titre of maternal IgG antibody to RSV was significantly higher (P < 0.001) in those mothers whose babies remained uninfected than in those whose babies had proved RSV infection before 6 months of age. Babies born to mothers with high levels of IgG antibody to respiratory syncytial virus were protected against infection with this virus during the first months of life when the risk of severe disease was greatest.     

婴幼儿呼吸道合胞病毒感染分子流行病学研究

目的　探讨婴幼儿呼吸道合胞病毒(RSV)感染的分子流行病学情况。方法　采用随机扩增多态DNA(RAPD)技术,对长春市儿童医院1992～1994年分离并鉴定的96株RSV和一株标准RSV进行RAPD分析。结果　所有RSV毒株都有扩增带,共有四种带型。不同疾病来源的RSV基因型不同。来源毛细支气管炎的RSV有8714%为R1型。结论　RAPD技术能从分子水平了解婴幼儿RSV感染情况;R1型RSV可能为引起婴幼儿毛细支气管炎的主要病原。