Antibody Responses In Infants Research Articles

Effect of Vaccination on Serotype-Specific Antibody Responses in Infants Administered WC3 Bovine Rotavirus before or after a Natural Rotavirus Infection

In an evaluation of WC3 bovine rotavirus (serotype 6) vaccine in infants, some subjects experienced a natural serotype 1 rotavirus infection before vaccination and others after. Therefore, the effects of both WC3 and natural rotavirus strains as either primary or boosting immunogens on serotype-specific neutralizing antibody responses could be determined. After primary natural infection (symptomatic or asymptomatic), neutralizing antibody titers were highest to serotype 1 but were consistently high to serotype 3, and low titers (greater than or equal to 20) to serotypes 2 and 4 were often detected. Previous vaccination with WC3 had little effect on the magnitude of these responses. In contrast, subjects infected with serotype 1 strains before vaccination experienced large (average, 12-fold) rises in neutralizing antibody to human serotypes 1-4 when vaccinated with WC3. Thus, although WC3 and the natural strains are distinct serotypes, their epitopes were sufficiently similar that reinfection with WC3 could boost neutralizing antibody titers to human serotypes in subjects primed by a previous natural infection.

Immunogenicity of a Haemophilus influenzae polysaccharide-Neisseria meningitidis outer membrane protein complex conjugate vaccine.

Polysaccharide-protein conjugate vaccines made with different carriers vary in their ability to elicit antipolysaccharide IgG antibody responses in young infants and an adult mouse model, suggesting that the carrier proteins used in the conjugate vaccines differ in their ability to act as carriers, or that additional mechanisms of immunogenicity play a role. A conjugate vaccine of Haemophilus influenzae PRP coupled to the outer membrane protein complex (OMPC) of Neisseria meningitidis serogroup B is immunogenic in children as young as 2 mo of age and is immunogenic in infant rhesus monkeys, an animal model for infant humans. In the present study, PRP-OMPC was found to induce efficient IgM to IgG switching of anti-PRP serum antibody in adult mice, whereas PRP conjugated to two other protein carriers did not. Thus the PRP-OMPC conjugate was examined in order to determine why PRP coupled to OMPC was so immunogenic, even more immunogenic than conjugates made with other carrier proteins. The OMPC carrier differs from the other protein carriers in that the proteins are present in a liposomal form containing lipids (including LPS) derived from the outer membrane of N. meningitidis. We studied the OMPC to see whether the different components or the nature of the OMPC carrier could contribute to its enhanced immunogenicity. Specifically we evaluated the OMPC for both classic Th cell carrier activity and adjuvanticity, and the LPS component of OMPC for systemic polyclonal B cell activation. Carrier recognition of the OMPC moiety of PRP-OMPC was demonstrated. In addition the PRP-OMPC conjugate vaccine was observed to have adjuvant properties for both T cell-dependent and T cell-independent Ag in the absence of LPS-induced systemic polyclonal B cell activation. These observations suggest that in addition to functioning as a classic protein carrier whereby the proteins in OMPC provide Th cell epitopes, the OMPC also has adjuvant activity that distinguishes it from other protein carriers and may contribute to the increased immunogenicity of PRP-OMPC conjugates in animal models.

Serotype 1 reassortant of bovine rotavirus WC3, strain WI79-9, induces a polytypic antibody response in infants

A reassortant rotavirus, strain W179-9, was constructed bearing gene 9 of serotype 1 rotavirus strain WI79 and all other genes derived from bovine (serotype 6) rotavirus strain WC3. The antigenic phenotype of WI79-9 is bivalent: serotype 1 and serotype 6. WI79-9 administered orally at a dose of 10(7.5) p.f.u. induced no adverse effects in 48 infants of age 2-11 months. Serotype 1- and serotype 6-specific serum neutralizing antibody titres were induced with approximately equal frequency in these infants. Serotype 1-specific antibody responses were inhibited in infants previously seropositive to type 1. The immune response rate was enhanced by administration of a second, 'booster dose'.

Local and systemic antibody response in infants after oral administration of inactivated enteropathogenicE. coli serotype O111 and O55

In ten infants divided into two groups (up to one month of age and at 2-7 months of age) the dynamics and formation of different antibody isotypes produced locally in the intestine and in serum after orally administered inactivated enteropathogenic E. coli strains O111 and O55 was followed during 30 d after the first and booster dose by using an indirect immunofluorescence method. Infants up to one month of age produced antibodies of IgM isotype in stool together with the IgA isotype after the first and booster dose of the vaccine against both antigens. Serum IgG antibody increased after 2 d following the first and second dose of antigens and remained higher during 5 d. The infants aged 2-7 months expressed predominantly the IgA isotype response in stool after the first and booster dose of antigens. The serum immunoglobulin levels did not change after oral antigen administration.

Viremia and neutralizing antibody response in infants with exanthem subitum

Mononuclear cell-associated viremia caused by human herpesvirus type 6 was detected in 39 (66%) of 59 blood samples from 38 children with exanthem subitum between day 0 and day 7 of the disease. The rate of virus isolation from mononuclear cells was 100% (26/26) on days 0 to 2 (just before appearance of skin rash), 82% (9/11) on day 3, 20% (2/10) on day 4, 7% (2/12) on days 5 to 7, and 0% (0/37) on day 8 and thereafter. The cell-free virus was detected in blood in 10 (21%) of 47 blood samples during the same period. The antibody activity to the virus, evaluated by a newly developed neutralization assay, was first detected on day 3 of the disease with a positive rate of 18% (2/11). It became 60% (6/10) on day 4, 75% (9/12) on days 5 to 7, and 100% on day 8 and thereafter. Thus the disappearance of the virus from blood was associated with the induction of specific immunity to the virus.

Effect of oligosaccharide chain length, exposed terminal group, and hapten loading on the antibody response of human adults and infants to vaccines consisting of Haemophilus influenzae type b capsular antigen unterminally coupled to the diphtheria protein CRM197.

Vaccines consisting of oligosaccharide (OS) derived from Haemophilus influenzae type b capsular polysaccharide and conjugated to carrier proteins had been shown capable of eliciting memory-type capsular polysaccharide of H. influenza type b antibody responses in human infants, but the structural variables governing immunogenicity were not defined. Here a series of conjugates were made with the diphtheria protein CRM197 and with uniterminally coupled OS haptens that varied in chain length, exposed terminal residue, or multiplicity of loading as defined by ribose/protein ratio. Adults were given a single injection, 1-yr-old infants were given a two-injection sequence, and capsular polysaccharide of H. influenzae type b antibody responses were assessed by radioantigen binding. Vaccines C-4r, C-6r, and C-12r, in which ribitol-ended OS of mean length 4, 6, or 12 repeat units were coupled at low hapten loading, were about equally immunogenic (geometric means 2 to 5 micrograms/ml in infants, 5 to 9 micrograms/ml in adults). Vaccine C7p was made with a higher loading of OS having mean length 7 repeat units and having mainly phosphate monoester at the exposed termini Vaccine C-7R was made from a portion of C-7p by enzymatic removal of most of the terminal phosphates. Compared to the C-4r, C-6r, and C-12r series, vaccines C-7p and C-7R induced geometric means about 10-fold higher in adults and 20-fold higher in infants. Thus OS chain length (in the range studied) and exposed terminus are less critical variables in this system than the extent of hapten loading.

Passive transfer of respiratory syncytial virus (RSV) antiserum suppresses the immune response to the RSV fusion (F) and large (G) glycoproteins expressed by recombinant vaccinia viruses.

In young infants who possess maternally derived respiratory syncytial virus (RSV) antibodies, the antibody response to RSV glycoproteins is relatively poor, despite extensive replication of RSV. In the present study, it was found that cotton rat RSV hyperimmune antiserum suppressed the antibody response to the RSV glycoproteins but not the response to vaccinia virus antigens when the antiserum was passively transferred to cotton rats prior to infection with vaccinia recombinant viruses expressing the RSV envelope glycoproteins. The cotton rats which had their immune responses suppressed by passively transferred antibodies were more susceptible to infection with RSV than were animals inoculated with control serum lacking RSV antibodies. Furthermore, many of the immunosuppressed animals infected with the vaccinia recombinant viruses developed RSV glycoprotein antibodies which had abnormally low neutralizing activities. Thus, preexisting serum RSV antibodies had dramatic quantitative and qualitative effects on the immune response to RSV glycoproteins, which may explain, in part, the poor RSV antibody response of young human infants to infection with RSV. Our observations also suggest that immunosuppression by preexisting, passively acquired RSV antibodies may constitute a major obstacle to RSV immunoprophylaxis during early infancy, when immunization is most needed.

Strain-specific serum antibody responses in infants undergoing primary infection with respiratory syncytial virus.

We sought to characterize the human respiratory syncytial virus (RSV) subgroup-specific antibody response to primary infection with RSV. RSV isolates from 43 infants and young children were typed as either subgroup A (Long strain-like) or B (18537 strain-like) based on reactivity with monoclonal antibodies. Acute-phase or preinfection and convalescent-phase sera were collected from the 43 subjects and tested in an enzyme-linked immunosorbent assay using purified F and G glycoproteins from RSV subgroups A and B and by neutralization assay against both subgroups of RSV. Twenty-six individuals had rises in titer of antibody to F glycoprotein, 27 to G glycoprotein, and 28 had rises in titer of neutralizing antibody. The antibody responses to homologous and heterologous F glycoproteins were not significantly different. In contrast, homologous vs. heterologous antibody responses to G glycoprotein were significantly different, with 7.3% relatedness between the G glycoproteins of subgroups A and B. Analysis of neutralizing antibody responses revealed 31% relatedness.

IMMUNOLOGIC PRIMING OF INFANTS WITH A SINGLE DOSE OF H. INFLUENZAE TYPE B (Hib) POLYSACCHARIDE-N. MENINGITIDIS OUTER MEMBRANE PROTEIN (PS-OMP) CONJUGATE VACCINE

In a trial of its immunogenicity, 13 children from 2-6 months of age received a single dose of PS-OMF conjugate vaccine. Titers of antibody against Hib capsular PS(PRP) one month after immunization were determined at Merck Laboratories by radioimmunoassay with the use of 125I extrinsic labelled antigen. All 13 children had <0.4μg of antibody/ml before receiving PS-OMP vaccine and 6/13 (46%) had ≥1.0μg/ml after a single dose (geometric mean: 5.2μg/ml).Because additional PS-OMP vaccine was not available and previous work suggested that the conjugate vaccine may prime infants to respond to plain PRP we administered PRP vaccine to all 7 children with <0.1μg of antibody/ml after PS-OMP vaccine and to 4 children with >1.0μg of antibody/ml after PS-OMP vaccine. Of the 7 children with <1.0μg of antibody/ml (geometric mean: 0.4μg/ml), 4 (57%) developed ≥1.0μg of antibody/ml (geometric mean: 5.2μg/ml) one month after “boosting” with PRP vaccine. Of the four children with >1.0μg of antibody/ml after PS-OMP vaccine, the titers of antibody one month after “boosting” with PRP vaccine increased in one child (from 19.6 to 31.2μg/ml), changed little in one child (from 1.0 to 1.1μg/ml) and decreased in two children (from 1.3 to 0.4μg/ml and from 1.5 to 0.4μg/ml, respectively). We conclude that the antibody responses of young infants to a single dose of PS-OMP conjugate vaccine vary: titers of antibody ≥1.0μg/ml develop in some infants, others are primed to achieve ≥1.0ug/ml after subsequent “boosting” with PRP vaccine, while others fail to have a substantial response.

Effect of age and preexisting antibody on serum antibody response of infants and children to the F and G glycoproteins during respiratory syncytial virus infection.

The serum antibody response of 50 infants and children infected with respiratory syncytial virus (RSV) was determined by a glycoprotein-specific enzyme-linked immunosorbent assay, and the effects of age and preexisting antibody titer at the time of RSV infection on response to the G and F glycoproteins of RSV were examined. The immune response to the G and F glycoproteins was assessed with anti-human immunoglobulin A to permit measurement of the response of young infants in the presence of maternally derived immunoglobulin G. The findings suggested that age primarily affects the response to the F glycoprotein and that preexisting antibody titer affects the response to the G glycoprotein.

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.

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.

The antibody response of seronegative infants to inactivated poliovirus vaccine of enhanced potency

The immunogenic efficacy of inactivated poliovirus vaccine of enhanced potency (IPV-E), containing 40, 8 and 32 D-antigen units of types 1, 2 and 3, respectively, was evaluated in tritypic seronegative infants. Eighty infants aged six to 45 weeks, with no antibody detectable at a 1 : 4 dilution, were given two doses of a quadruple vaccine containing diphtheria-pertussistetanus (DPT) vaccine and IPV-E at intervals of four weeks (37 infants, group 1) or eight weeks (43 infants, group 2) between doses. All infants of group 2 responded with antibody to the three types of polioviruses. In group 1, all responded to types 1 and 3 antigens but only 36 responded to type 2. Antibody titres were higher in infants immunized at eight week than at four week intervals. Thus, two doses of IPV-E, especially when given eight weeks apart, are sufficient for primary immunization against poliomyelitis. If DPT vaccine of enhanced potency is combined with IPV-E, two doses of such a quadruple vaccine may be sufficient for primary immunization against four diseases; this possibility deserves evaluation.

Antibody response of infants to two doses of inactivated poliovirus vaccine of enhanced potency.

The conventional formulation of injectable poliovirus vaccine (inactivated) contains 20, 2, and 4 D-antigen units of types 1, 2, and 3 polioviruses. Primary immunization requires three doses given at intervals of at least four weeks. A new formulation with 40, 8, and 32 D-antigen units of the three poliovirus types has been prepared to reduce primary immunization to two doses. We evaluated the immunogenic efficacy of this new formulation supplied to us as a liquid vaccine containing diphtheria-pertussis-tetanus vaccines and inactivated poliovirus vaccine. Two doses were administered four weeks apart to 100 infants and eight weeks apart to 114 infants. Antibody titers were determined against the three types of polioviruses before and after immunization. The effects of age, presence of maternal antibody, and interval between doses of the frequency and titers of antibody response were assessed. Irrespective of age or interval between doses, the seroconversion rates to types 1 and 3 antigens were 90% to 100%. To type 2 antigen the rate was below 84% in the 6- to 7-week-old infants, 88% to 95% in 8- to 12-week-old infants, and 90% to 100% in 13- to 45-week-old infants. The seroconversion rates and geometric mean titers of antibody were lower in those infants with maternal antibody than in those without maternal antibody at the time of receiving the first dose. The best results were in infants 8 weeks of age or older, in whom the two doses were given eight weeks apart. We recommend this schedule.

Response of preterm infants to diphtheria-tetanus-pertussis immunizations

To establish guidelines for the routine use of diphtheria, tetanus, and pertussis (DTP) vaccine in preterm infants, we quantitated antibody responses of preterm infants to DTP and determined the nature and extent of side effects. Twenty-five preterm infants were immunized with 0.5 ml DTP vaccine at routine intervals. Term infants served as controls. Immediately before each immunization and 2 months after the third, DTP-specific antibodies were quantitated. Clinical side effects were determined by parental report. After the second immunization, 100% of preterm infants had evidence of specific antibody production against diphtheria, tetanus, and pertussis. The incidence of side effects was low, but irritability was significantly more common in preterm infants after the second immunization. These observations suggest that the initiation of primary immunization with DTP in preterm infants need not be delayed beyond 2 months of age.

1134 STUDIES OF SAFETY AND IMMUNOGENICITY OF HAEMOPHILUS INFLUENZAE TYPE B POLYSACCHARIDE DIPHTHERIA TOXOID CONJUGATE VACCINE (PRP-D) IN CHILDREN 7–14 MONTHS OF AGE

In a multicenter study, 502 normal infants ages 7-14 months were randomized to receive either 2 doses of PRP-D intramuscularly containing 20 ug PRP (80%) or placebo (20%) 6-10 weeks apart. Serum samples were obtained from 25% prior to each injection and 1 month post second dose and tested by Farr-type radioimmunoassay for anti-PRP antibody. Reaction data are available from 400 subjects. The incidence of local erythema at the injection site was 2.4% and irritability 3% in both groups. Two PRP-D recipients had temperatures greater than 1022(R). Among 120 children tested for antibody, 99% of PRP-D recipients demonstrated a two fold or greater rise in anti-PRP compared with 5% of placebo recipients. Median anti-PRP levels in the two groups were 7.0 and 0.012 ug/ml respectively. After 2 doses of PRP-D, 95% had ≥ 0.15 ug/ml antibody protein/ml and 90% had > 1 ug/ml. This study confirms prior observations in 9-14 month olds that PRP-D can induce primary and booster antibody responses in infants over 7 months compatible with protection against H. influenzae b disease.

IgG and IgM pneumococcal polysaccharide antibody responses in infants.

The ontogeny of human antibody responses to pneumococcal polysaccharide antigens was studied by determining whether the age at immunization affects the level and/or immunoglobulin isotype of antibody produced. Twenty-nine healthy infants between 2 and 18 months of age and 13 normal adults were studied. Responses were found to vary markedly with the age at the time of immunization and with the pneumococcal serotype tested. Three general patterns of isotype-specific antibody response were observed in the infants: a high response in IgG antibody occurred as early as 2 months of age following immunization with type 3 pneumococcal polysaccharide; little or no response was noted in either IgG or IgM antibody with types 6, 18, and 19; and intermediate responses with IgM antibody increases greater than IgG increases were found for type 23. These data suggest that different factors control the immunologic response of infants to various pneumococcal polysaccharide serotypes following immunization at various ages.

Development of respiratory mucosal tolerance during Haemophilus influenzae type B infection in infancy.

Abstract Groups of patients with different forms of infection with Haemophilus influenzae type B (Hib), namely meningitis, epiglottitis, arthritis, and periorbital cellulitis, were evaluated for the appearance of serum IgG, IgA, IgM, and nasopharyngeal secretory (NPS) IgA (SIgA) antibody response to Hib capsular antigen at various intervals after the onset of clinical illness, by using an indirect enzyme-linked immunosorbent assay. The serum immune response was characterized by its predictable absence in infants under 23 mo of age, and in those with meningitis who, regardless of age, had high levels of circulating antigen. On the other hand, antibody response was frequently detected in the serum of older infants. Significantly, however, the appearance of SIgA antibody was demonstrated in virtually all patients with Hib infections under 23 mo of age. In addition, a positive correlation was observed between the concentration of antigen NPS, the level of SIgA activity in the NPS, and the absence of antibody response in the serum. These observations are strikingly similar to the development of systemic hyporesponsiveness (oral tolerance) observed after oral administration of certain infectious or nonreplicating antigens in experimental animals. It is suggested that similar mechanisms may underlie the immunologic abnormalities observed in the serum antibody response in infants with Hib meningitis.

Antibody response to oral polio vaccine in premature infants

APPROXIMATELY 50% OF TERM INFANTS will obtain protection to all three Serotypes of orally administered polio vaccine after a single dose at 2 months of age; multiple vaccine doses will increase the protection to 83% to 96% of children, v9 However, the optimal time to administer OPV to a child born prematurely has not been determined. The American Academy of Pediatrics recommends giving the first dose of OPV to a premature infant at 2 months of chronologic age if the child has been discharged from the hospital and is otherwise healthyJ ~ The Academy notes, however, that this recommendation is not based on adequate data. This study was undertaken to determine whether the antibody response in preterm infants to OPV given at 2 and 4 months of age is comparable to that in term infants.

Evaluation of the protective efficacy of Haemophilus influenzae type b vaccines in an animal model

The infant rat model for Haemophilus influenzae type b (Hib) disease was modified to test the protective efficacy of candidate vaccines. The administration of 0.4 micrograms of polyribosylribitol phosphate (PRP) combined with pertussis vaccine or with diphtheria toxoid-tetanus toxoid-pertussis vaccine (DTP) to infant rats at 5, 10, and 15 days of age resulted in significant (P less than 0.001) protection against Hib bacteremia after challenge at 20 days of age. A dose-response effect was demonstrated, and suppression of the protective effect was noted with high doses of PRP. The administration of pertussis vaccine alone or DTP alone did not protect against Hib bacteremia. The degree of protection against Hib bacteremia correlated (P less than 0.005) with the serum anti-PRP antibody response measured before bacterial challenge. High-molecular-weight PRP preparations administered alone or in combination with pertussis vaccine were less effective than standard PRP combined with pertussis vaccine. These data compare favorably with the antibody response in human infants receiving the same vaccines. The observations in this animal model should facilitate the development and testing of other vaccine preparations for human infants.