ABSTRACT
BACKGROUND: Two doses of measles, mumps, and rubella (MMR) vaccine are 97% effective against measles, but waning antibody immunity to measles and failure of the 2-dose vaccine occur. We administered a third MMR dose (MMR3) to young adults and assessed immunogenicity over 1 year. METHODS: Measles virus (MeV) neutralizing antibody concentrations, cell-mediated immunity (CMI), and immunoglobulin G (IgG) antibody avidity were assessed at baseline and 1 month and 1 year after MMR3 receipt. RESULTS: Of 662 subjects at baseline, 1 (0.2%) was seronegative for MeV-neutralizing antibodies (level, <8 mIU/mL), and 23 (3.5%) had low antibody levels (8-120 mIU/mL). One month after MMR3 receipt, 1 subject (0.2%) was seronegative, and 6 (0.9%) had low neutralizing antibodies, with only 21 of 662 (3.2%) showing a ≥ 4-fold rise in neutralizing antibodies. One year after MMR3 receipt, no subject was seronegative, and 10 of 617 (1.6%) had low neutralizing antibody levels. CMI analyses showed low levels of spot-forming cells after stimulation, suggesting the presence of T-cell memory, but the response was minimal after MMR3 receipt. MeV IgG avidity did not correlate with findings of neutralization analyses. CONCLUSIONS: Most subjects were seropositive before MMR3 receipt, and very few had a secondary immune response after MMR3 receipt. Similarly, CMI and avidity analyses showed minimal qualitative improvements in immune response after MMR3 receipt. We did not find compelling data to support a routine third dose of MMR vaccine.
Subject(s)
Antibodies, Neutralizing/blood , Antibodies, Viral/blood , Immunity, Cellular/physiology , Immunoglobulin G/blood , Measles virus/immunology , Measles-Mumps-Rubella Vaccine/immunology , Adolescent , Adult , Antibody Affinity , Cohort Studies , Female , Humans , Immunization Schedule , Longitudinal Studies , Male , Measles-Mumps-Rubella Vaccine/administration & dosage , Neutralization Tests , Odds Ratio , Young AdultABSTRACT
BACKGROUND: Given the high infant measles mortality rate, there is interest in whether a measles immunization regimen beginning at <12 months of age provides lasting immunity. METHODS: Measles-specific immune responses were evaluated in 70 children aged 5-10 years after primary measles vaccine administered at 6, 9, or 12 months. RESULTS: At 5-10 years of age, the stimulation index for measles T-cell proliferation was 11.4 (SE, 1.3), 10.9 (SE, 1.5), and 14.4 (SE 2.1) when the first measles dose was given at 6, 9, or 12 months, respectively. Neutralizing antibody concentration (geometric mean titer [GMT]) in those immunized at 6 months of age was 125 mIU/mL (95% confidence interval [CI], 42-377) in the presence of passive antibodies (PAs) and 335 mIU/mL (95% CI, 211-531) in those without PAs; in those immunized at 9 months, GMTs were 186 mIU/mL (95% CI, 103-335) and 1080 mIU/mL (95% CI, 642-1827) in the presence and absence of PAs, respectively. The GMT was 707 mIU/mL (95% CI, 456-1095) when vaccine was administered at 12 months (P ≤ .04). CONCLUSIONS: Measles-specific T-cell responses were sustained at 5-10 years of age regardless of age at time of primary measles immunization. Neutralizing antibody concentrations were lower in cohorts given the first vaccine dose at 6 months of age and in the presence of PAs; however, responses could be boosted by subsequent doses. Starting measles vaccination at <12 months of age may be beneficial during measles outbreaks or in endemic areas.
Subject(s)
Antibodies, Viral/blood , Measles Vaccine/administration & dosage , Measles Vaccine/immunology , Measles virus/immunology , Measles/immunology , T-Lymphocytes/immunology , Antibodies, Neutralizing/blood , Child , Child, Preschool , Female , Humans , Immunity, Cellular , Immunization Schedule , Lymphocyte Activation , Male , Measles/prevention & control , VaccinationABSTRACT
BACKGROUND: Few studies have used quantitative polymerase chain reaction (qPCR) as an approach to measure virus neutralization assay endpoints. Its lack of use may not be surprising considering that sample nucleic acid extraction and purification can be expensive, labor-intensive, and rate-limiting. METHODS: Virus/antibody mixtures were incubated for one hour at 37°C and then transferred to Vero cell monolayers in a 96-well plate format. At 24 (or 48) hours post-infection, we used a commercially available reagent to prepare cell lysates amenable to direct analysis by one-step SYBR Green quantitative reverse transcription PCR using primers specific for the RSV-N gene, thereby obviating the need for cumbersome RNA extraction and purification. The neutralization titer was defined as the reciprocal of the highest dilution needed to inhibit the PCR signal by 90% when compared with the mean value observed in virus control wells in the absence of neutralizing antibodies. RESULTS: We have developed a qPCR-based neutralization assay for human respiratory syncytial virus. Due to the sensitivity of qPCR in detecting virus replication, endpoints may be assessed as early as 24 hours post-infection. In addition, the dynamic range of qPCR provides a basis for the assay to be relatively robust to perturbations in input virus dose (i.e., the assay is in compliance with the Percentage Law). CONCLUSIONS: This qPCR-based neutralization assay is suitable for automated high-throughput applications. In addition, our experimental approach may be generalizable for the rapid development of neutralization assays for other virus families.
Subject(s)
Antibodies, Neutralizing/blood , Antibodies, Viral/blood , Neutralization Tests/methods , Real-Time Polymerase Chain Reaction/methods , Respiratory Syncytial Virus, Human/immunology , Viral Load/methods , Animals , Humans , RabbitsABSTRACT
BACKGROUND: Response rates and immunologic memory following measles vaccination are reduced in human immunodeficiency virus (HIV)-infected children in the absence of highly active antiretroviral therapy (HAART). METHODS: HIV-infected children 2 to <19 years old receiving HAART and with HIV loads <30,000 copies/mL, CD4% ≥15, and ≥1 prior measles-mumps-rubella vaccination (MMR) were given another MMR. Measles antibody concentrations before and 8, 32, and 80 weeks postvaccination were determined by plaque reduction neutralization (PRN). A subset was given another MMR 4-5 years later, and PRN antibody was measured before and 7 and 28 days later. RESULTS: At entry, 52% of 193 subjects were seroprotected (PRN ≥120 mIU/mL). Seroprotection increased to 89% 8 weeks postvaccination, and remained at 80% 80 weeks postvaccination. Of 65 subjects revaccinated 4-5 years later, 85% demonstrated memory based on seroprotection before or 7 days after vaccination. HIV load ≤400 copies/mL at initial study vaccination was associated with higher seroprotection rates, greater antibody concentrations, and memory. Grade 3 fever or fatigue occurred in 2% of subjects. CONCLUSIONS: Measles revaccination induced high rates of seroprotection and memory in children receiving HAART. Both endpoints were associated with HIV viral load suppression. CLINICAL TRIALS REGISTRATION: NCT00013871 (www.clinicaltrials.gov).
Subject(s)
Antiretroviral Therapy, Highly Active/methods , HIV Infections/drug therapy , HIV Infections/immunology , Immunization, Secondary/methods , Immunologic Memory , Measles Vaccine/adverse effects , Measles Vaccine/immunology , Adolescent , Antibodies, Neutralizing/blood , Antibodies, Viral/blood , CD4 Lymphocyte Count , Child , Child, Preschool , Female , HIV-1/isolation & purification , Humans , Infant , Male , Measles Vaccine/administration & dosage , Neutralization Tests , Viral Load , Viral Plaque AssayABSTRACT
UNLABELLED: BACKGROUND.: ACTG (Pediatric AIDS Clinical Trials Group) 225, a multicenter, randomized, open-label trial in the United States evaluated reactogenicity and immunogenicity of 2 vaccination regimens: monovalent measles vaccine (Attenuvax) at 6 months of age and measles, mumps, and rubella, live attenuated (MMRII) vaccine at 12 months of age (2D), or only MMRII at 12 months of age (1D) in human immunodeficiency virus-infected (HIV-infected) (POS) and uninfected (NEG) children in the pre-highly active antiretroviral therapy (pre-HAART) period. METHODS: Plaque-reduction neutralization (PRN) of measles-neutralizing antibody titers were evaluated at study weeks 0, 6, 26, 32, 52, and 130 (â¼3 years of age). RESULTS: The 110 subjects included: 65 2DNEG; 30 1DNEG; 7 2DPOS and 8 1DPOS. Vaccinations (n=175) were associated with no adverse experiences >Grade 2 except for Grade 3 fever (n=2, 1 1DPOS and 1 1DNEG). Six weeks after Attenuvax, all 2DPOS subjects (7/7) seroresponded (PRN titers ≥120 mIU/mL) with median titers significantly exceeding 2DNEG titers (2115 vs 628 mIU/mL, respectively; P=.023). At â¼3 years of age, 67% 1DPOS (4/6) and 83% 2DPOS (4/5) subjects maintained titers ≥120 mIU/mL. Prevaccination titers ≥25 mIU/mL among 2DNEG subjects correlated inversely with the likelihood of achieving titers ≥120 mIU/mL (56% vs 90%; P=.004). CONCLUSIONS: Among HIV-infected children pre-HAART, Attenuvax at 6 months was well tolerated and immunogenic. These data support the current World Health Organization (WHO) recommendation to administer a first dose of measles vaccine at 6 months of age to HIV-infected children.
Subject(s)
Antibodies, Neutralizing/blood , HIV Infections/complications , Measles Vaccine/adverse effects , Measles Vaccine/immunology , Measles/prevention & control , Antibodies, Viral/blood , CD4 Lymphocyte Count , Child, Preschool , Female , HIV Infections/epidemiology , HIV Infections/transmission , Humans , Immunization Schedule , Infectious Disease Transmission, Vertical , Male , Measles/complications , Measles-Mumps-Rubella Vaccine/administration & dosage , Measles-Mumps-Rubella Vaccine/immunology , Pregnancy , United States/epidemiology , Vaccines, Attenuated/adverse effects , Vaccines, Attenuated/immunology , Viral Matrix Proteins/immunologyABSTRACT
BACKGROUND: Previously, we demonstrated that measles antibody prevalence was lower at age 12 months among children infected with human immunodeficiency virus (HIV) than uninfected children following measles vaccination (MV) at ages 6 and 9 months. Among HIV-uninfected children, measles antibody prevalence was lower among 1- than 2-dose MV recipients. Here, we report results through age 24 months. METHODS: Children born to HIV-infected mothers received MV at 6 and 9 months, and children of HIV-uninfected mothers were randomized to MV at 6 and 9 months or MV at 9 months. We followed children through age 24 months. The child's HIV status was determined and measles immunoglobulin G (IgG) level was measured by enzyme immunoassay (EIA) and by plaque reduction neutralization (PRN) on a subset. RESULTS: Among HIV-uninfected children, the difference in measles antibody prevalence at age 12 months between one- and two-dose recipients reported previously by EIA was shown to be smaller by PRN. By age 24 months, 84% and 87% of HIV-uninfected children receiving 1 or 2 doses, respectively, were seroprotected. Only 41% of 22 HIV-infected children were measles seroprotected at age 20 months. DISCUSSION: Measles seroprotection persisted through age 24 months among HIV-uninfected children who received 1 or 2 doses of MV. HIV-infected children demonstrated seroprotection through age 12 months, but this was not sustained.
Subject(s)
Antibodies, Viral/blood , HIV Infections/immunology , Measles Vaccine/administration & dosage , Measles Vaccine/immunology , Measles/prevention & control , Dose-Response Relationship, Immunologic , Drug Administration Schedule , Female , HIV Infections/complications , HIV Infections/epidemiology , Humans , Immunocompromised Host , Immunoenzyme Techniques , Infant , Malawi/epidemiology , Male , Measles virus/immunology , Neutralization TestsABSTRACT
Waning immunity or secondary vaccine failure (SVF) has been anticipated by some as a challenge to global measles elimination efforts. Although such cases are infrequent, measles virus (MeV) infection can occur in vaccinated individuals following intense and/or prolonged exposure to an infected individual and may present as a modified illness that is unrecognizable as measles outside of the context of a measles outbreak. The immunoglobulin M response in previously vaccinated individuals may be nominal or fleeting, and viral replication may be limited. As global elimination proceeds, additional methods for confirming modified measles cases may be needed to understand whether SVF cases contribute to continued measles virus (MeV) transmission. In this report, we describe clinical symptoms and laboratory results for unvaccinated individuals with acute measles and individuals with SVF identified during MeV outbreaks. SVF cases were characterized by the serological parameters of high-avidity antibodies and distinctively high levels of neutralizing antibody. These parameters may represent useful biomarkers for classification of SVF cases that previously could not be confirmed as such using routine laboratory diagnostic techniques.
Subject(s)
Measles Vaccine/administration & dosage , Measles Vaccine/immunology , Measles virus/classification , Measles/immunology , Adolescent , Age Distribution , Antibodies, Neutralizing , Antibodies, Viral/blood , Antibody Affinity , Biomarkers , Child , Child, Preschool , Humans , Immunoglobulin M/blood , Immunoprecipitation , Infant , Measles/diagnosis , Measles/epidemiology , Measles/prevention & control , Measles virus/immunology , United States/epidemiology , Young AdultABSTRACT
BACKGROUND: A 30-second aerosol measles vaccination successfully primes children 12 months of age and older but is poorly immunogenic when given to 9-month-old children. We examined the immune responses when increasing the duration to aerosol exposure in 9-month-olds. METHODS: One hundred and thirteen healthy 9-month-old children from Mexico City were enrolled; 58 received aerosol EZ measles vaccine for 2.5 minutes and 55 subcutaneously. Measles-specific neutralizing antibodies and cellular responses were measured before and at 3 and 6 months postimmunization. RESULTS: Adaptive immunity was induced in 97% after aerosol and 98% after subcutaneous administration. Seroconversion rates and GMCs were 95% and 373 mIU/mL (95% confidence interval [CI], 441-843) following aerosol vaccination and 91% and 306 mIU/mL (95% CI, 367-597) after subcutaneous administration at 3 months. The percentage of children with a measles-specific stimulation index ≥3 was 45% and 60% in the aerosol versus 55% and 59% in the subcutaneous group at 3 and 6 months, respectively. CD8 memory cell frequencies were higher in the aerosol group at 3 months compared with the subcutaneous group. Adverse reactions were comparable in both groups. CONCLUSIONS: Increasing exposure time to aerosol measles vaccine elicits immune responses that are comparable to those seen when an equivalent dose is administered by the subcutaneous route in 9-month-old infants.
Subject(s)
Antibodies, Viral/blood , Measles Vaccine/administration & dosage , Vaccination , Adaptive Immunity , Aerosols , Female , Humans , Infant , Interferon-gamma/biosynthesis , Lymphocyte Activation , Male , Measles Vaccine/immunology , Mexico , T-Lymphocytes/immunology , Time FactorsABSTRACT
In this study, we illustrate, for the first time, that preexisting low-avidity neutralizing measles maternal antibodies do not interfere with the development of high concentrations of high-avidity measles antibodies in children immunized at age 12 months. This suggests that the quality of measles maternal antibodies, rather than the quantity, impacts immunogenicity of primary measles immunization.
Subject(s)
Measles , Mumps , Antibodies, Viral , Antibody Formation , Child , Humans , Infant , Measles/prevention & control , Measles Vaccine , Measles-Mumps-Rubella VaccineABSTRACT
INTRODUCTION: Japanese encephalitis (JE) virus is the leading cause of viral encephalitis across temperate and tropical zones of Asia. The live attenuated SA 14-14-2 JE vaccine (CD-JEV) is one of three vaccines prequalified by the World Health Organization (WHO) to prevent JE. When incorporating a new vaccine into a country's Expanded Program on Immunization (EPI), it is important to show that the new vaccine can be administered concurrently with other routine pediatric vaccines without impairing the immune responses or changing the safety profiles of the co-administered vaccines. This Phase 4 open-label study evaluated the safety and immunogenicity of measles-mumps-rubella (MMR) vaccine co-administered with CD-JEV. METHODS: The study randomized 628 healthy Filipino children aged between 9 and 10 months to receive MMR and CD-JEV concurrently or separately. MMR immunogenicity was measured 56 days after MMR vaccination using a measles plaque reduction neutralization test (PRNT), anti-mumps immunoglobulin G (IgG) enzyme-linked immunosorbent assay (ELISA), and anti-rubella IgG ELISA, respectively. Neutralizing antibody against JE virus was measured 28 days after CD-JEV vaccination using PRNT. Safety was assessed through solicitation of immediate reactions, adverse events (AEs) within 14 days of vaccination, unsolicited AEs occurring within 28 days, and serious adverse events (SAEs) during participation in the study. RESULTS/CONCLUSIONS: During the study, no post-vaccinal encephalitis cases or related SAEs were reported in either group. Concurrent immunization with CD-JEV and MMR vaccines was not associated with any unusual safety signals when compared with sequential immunization. No significant differences between the regimens were seen in seropositivity or serology titer/concentration results for any of the antigens. Co-administration of CD-JEV and MMR was non-inferior to single administration of either vaccine.
ABSTRACT
Measles virus is highly infectious and remains a leading cause of vaccine preventable deaths in children. Neutralizing antibody responses elicited by measles virus infection or immunization are a serological correlate of protection. We describe a high-throughput neutralization assay to improve surveillance for measles immunity. Measles virus-antibody mixtures were incubated on Vero cell monolayers and 24 hours later cell-lysates harvested and subjected to one-step SYBR green RT-qPCR to amplify a target sequence within the measles virus nucleoprotein gene. Neutralization endpoint titers were interpolated to determine the dilution that inhibited the relative amplicon copy number by at least 90% compared to the mean signal obtained in virus control wells in the absence of serum. Anti-measles virus and anti-measles hemagglutinin antisera specifically neutralized measles virus in the microneutralization RT-qPCR assay while pre-immune sera and sera raised against other viruses did not. The microneutralization RT-qPCR assay obeyed the Percentage Law for measles virus inputs ranging from 100-5000 TCID50/well. The linear range of the assay corresponds to measles antibody concentrations of 30 to 3000 mIU/mL. Bland-Altman analysis and two-way analysis of variance demonstrated that results obtained using the microneutralization RT-qPCR assay were comparable to those obtained using a plaque reduction neutralization test and correctly identified human serum samples that were seropositive (95% and 100%, sensitivity and specificity, respectively). Furthermore, these comparisons suggest that a concentration of 300 mIU/mL may be a conservative cut-point to use to identify individuals likely to be protected against severe measles disease when the endpoint is based on 90% inhibition of virus replication. Measles virus microneutralization RT-qPCR is a rapid, sensitive, specific, and robust assay for detecting measles neutralizing antibodies that may help to improve immunization strategies nationally and achieve measles elimination globally.
Subject(s)
Antibodies, Neutralizing/analysis , Enzyme-Linked Immunosorbent Assay , Measles virus/immunology , Measles/prevention & control , Animals , Chlorocebus aethiops , Humans , Measles/diagnosis , Measles/immunology , Neutralization Tests/methods , Population Surveillance , Sensitivity and Specificity , Vero CellsABSTRACT
Respiratory syncytial virus (RSV) causes severe lower respiratory tract disease in infants and the elderly. Although there is no licensed vaccine, RSV-F and -G glycoproteins are targets for vaccine development and therapeutics. We developed an assay that can detect anti-RSV-G IgG antibodies, either as a biomarker of natural exposure or immunization. RSV genes encoding native and mutated G (mG) proteins from subgroups A and B strains were cloned, expressed as luciferase-tagged proteins, and tested individually to detect anti-RSV-G specific IgG antibodies using a high-throughput luciferase immunoprecipitation system (LIPS-G). RSV monoclonal antibodies and polyclonal antisera specifically bound in the LIPS-GA and/or -GB assays; whereas anti-RSV-F and -N, and antisera against measles virus or human metapneumovirus did not bind. Anti-RSV-GA and -GB IgG responses detected in mice infected intranasally with RSV-A or -B strains were subtype specific. Subtype specific anti-RSV-GA or -GB IgG responses were also detected using paired serum samples from infants while human adolescent serum samples reacted in both LIPS-GA and -GB assays, reflecting a broader experience.
ABSTRACT
BACKGROUND: The age at which passively acquired antibodies are lost is critical to determining the optimal age for measles vaccination. Little is known about the influence of human immunodeficiency virus type 1 (HIV-1) infection on levels of prevaccination antibodies to measles virus. METHODS: Antibodies to measles virus were measured by plaque reduction neutralization assay in HIV-1-infected, HIV-seropositive but uninfected, and HIV-seronegative Zambian infants aged 6 weeks to 9 months. Regression models were used to estimate age-specific antibody concentrations. RESULTS: Neutralizing antibodies to measles virus were measured in 652 plasma samples collected from 448 infants, of whom 61 (13.6%) were HIV-1 infected, 239 (53.4%) were HIV seropositive but uninfected, and 148 (33%) were HIV seronegative. The best fitting model suggests that HIV-1-infected infants have lower levels of passively acquired antibodies to measles virus at birth than do HIV-seronegative infants, but their antibody levels decrease more slowly. By 6 months of age, 91% (95% confidence interval, 83%-99%) of HIV-1-infected infants, 83% (95% confidence interval, 77%-89%) of HIV-seropositive but uninfected infants, and 58% (95% confidence interval, 51%-64%) of HIV-seronegative infants were estimated to have antibody levels that were unlikely to affect immune responses to measles vaccine (cutoff value for immune response, <50 mIU/mL). By 9 months of age, 99% of all infants had antibody levels <50 mIU/mL. CONCLUSIONS: Infants born to HIV-1-infected women are less likely to have passively acquired antibodies that would neutralize measles vaccine virus and, thus, have an increased risk of measles prior to the age of routine vaccination. Protection could be achieved by administration of the first dose of measles vaccine prior to 9 months of age.
Subject(s)
HIV Infections/complications , HIV Infections/transmission , Measles virus/immunology , Adult , Antibodies, Viral/blood , Female , Humans , Immunity, Maternally-Acquired , Infant , Infectious Disease Transmission, Vertical , Male , Pregnancy , Pregnancy Complications, Infectious , Zambia/epidemiologyABSTRACT
OBJECTIVE: To evaluate the persistence of measles antibodies after 2 doses of measles vaccine in a setting where exposure to wild-type measles was unlikely. Measles was declared eliminated from the United States in 2000, an achievement attributed to effective implementation of a routine 2-dose vaccination policy. Some have questioned whether measles transmission could resume if immunity wanes in the absence of boosting from wild-type measles. DESIGN: Prospective, observational, volunteer cohort study. SETTING: Rural Wisconsin health maintenance organization. PARTICIPANTS: Children who received the second measles vaccine dose at kindergarten (aged 4-6 years) or middle school (aged 10-12 years) in 1994 or 1995. Serum samples were collected periodically during a 10-year period for the kindergarten group and a 5-year period for the middle school group. INTERVENTION: Second dose of measles vaccine. MAIN OUTCOME MEASURE: Measles antibody levels were assessed by plaque-reduction neutralization: titers less than 8 mIU/mL were considered seronegative and suggestive of susceptibility to measles, and titers of 120 mIU/mL or less were considered low and suggestive of potential susceptibility. RESULTS: During the study period, no measles was reported in the study area. Voluntary attrition reduced the study population from 621 at enrollment to 364 (58.6%) by study end. Before the second dose, 3.1% (19/621) had low titers, of whom 74% (14/19) were antibody-negative, with geometric mean titers being significantly higher in kindergarteners (1559 mIU/mL) than in middle schoolers (757 mIU/mL) and rates of negativity significantly lower (1.0% [3/312] vs 3.6% [11/309]). One month after the second dose, 0.2% (1/612) had low titers and none was seronegative, with geometric mean titers being significantly higher in kindergarteners (2814 mIU/mL) than in middle schoolers (1672 mIU/mL). By study end, 4.9% (18/364) had low titers and none was seronegative, with no significant difference in geometric mean titers between kindergarteners (641 mIU/mL) and middle schoolers (737 mIU/mL) when both groups were aged 15 years. Projections suggest that the proportion of persons with low antibody levels may increase over time. CONCLUSIONS: Measles antibody persisted in all vaccinees available for follow-up 10 years after a second dose of vaccine, with no seronegative results detected. Declining titers suggest the need for vigilance in ensuring disease protection for the vaccinated population.
Subject(s)
Antibodies, Viral/immunology , Measles Vaccine/administration & dosage , Measles virus/immunology , Measles/prevention & control , Adolescent , Child , Child, Preschool , Humans , Prospective StudiesABSTRACT
BACKGROUND: The long-term antibody response to measles vaccine (MV) administered at age 6 months with or without subsequent doses is not well documented. METHODS: Measles serum antibody responses were evaluated after a supplemental dose of measles vaccine (sMV) administered at a median age of 20 months among Malawian children who had previously received 2 doses of measles vaccine (MV) at ages 6 and 9 months (HIV-infected and random sample of HIV-uninfected) or 1 dose at age 9 months (random sample of HIV-uninfected). We compared measles antibody seropositivity between groups by enzyme linked immunoassay and seroprotection by plaque reduction neutralization geometric mean concentrations. RESULTS: Of 1756 children enrolled, 887 (50.5%) received a sMV dose following MV at 9 months of age and had specimens available after sMV receipt, including 401 HIV-uninfected children who received one MV dose at 9 months, 464 HIV-uninfected and 22 HIV-infected children who received two doses of MV at ages 6 and 9 months. Among HIV-uninfected children, protective levels of antibody were found post sMV in 90-99% through ages 24-36 months and were not affected by MV schedule. Geometric mean concentration levels of measles antibody were significantly increased post-sMV among those HIV-uninfected children previously non-responsive to vaccination. Among HIV-infected children, the proportion seroprotected increased initially but by 9 months post-sMV was no higher than pre-sMV. CONCLUSIONS: Our findings support early 2-dose MV to provide measles immunity for young infants without risk of interference with antibody responses to subsequent MV doses administered as part of SIAs.
Subject(s)
HIV Infections , Immunity, Humoral , Immunization, Secondary , Measles Vaccine/therapeutic use , Antibodies, Viral/blood , Antibody Formation , Female , Humans , Immunization Schedule , Infant , Malawi , Male , Measles/prevention & control , Measles Vaccine/administration & dosageABSTRACT
The nucleoprotein of respiratory syncytial virus (RSV-N) is immunogenic and elicits an IgG response following infection. The RSV-N gene was cloned into a mammalian expression vector, pREN2, and the expressed luciferase-tagged protein (Ruc-N) detected anti-RSV-N-specific IgG antibodies using a high-throughput immunoprecipitation method (the luciferase immunoprecipitation system [LIPS]-N(RSV) assay). The specificity of the assay was evaluated using monoclonal antibodies (MAbs) and monospecific pre- and postimmunization rabbit antisera. Blood serum samples from chimpanzees and humans with proven/probable RSV infection were also tested. The pre- and postimmunization serum samples from rabbits given human metapneumovirus (HMPV) or measles virus were negative when tested by the LIPS-N(RSV) assay, while antisera obtained after immunization with either the RSV-A or RSV-B strain gave positive signals in a dose-dependent manner. RSV-N MAb 858-3 gave a positive signal in the LIPS-N(RSV) assay, while MAbs against other paramyxovirus nucleoproteins or RSV-F or RSV-G did not. Serum samples from chimpanzees simultaneously immunized with vaccinia-RSV-F and vaccinia-RSV-G recombinant viruses were negative in the LIPS-N(RSV) assay; however, anti-RSV-N IgG responses were detected following subsequent RSV challenge. Seven of the 12 infants who were seronegative at 9 months of age had detectable anti-RSV-N antibodies when they were retested at 15 to 18 months of age. The LIPS-N(RSV) assay detects specific anti-RSV-N IgG responses that may be used as a biomarker of RSV infection.
Subject(s)
Antibodies, Viral/blood , Immunoglobulin G/blood , Immunoprecipitation/methods , Luciferases/analysis , Nucleoproteins/immunology , Respiratory Syncytial Virus Infections/diagnosis , Respiratory Syncytial Virus, Human/immunology , Animals , Antigens, Viral/immunology , Humans , Infant , Pan troglodytes , Rabbits , Sensitivity and Specificity , Viral Proteins/immunologyABSTRACT
The prevalence of antibodies to measles, mumps, and rubella in US military recruits is of importance to public health leaders. We performed ELISA testing using a commercially available product on samples from 537 recruits obtained in 1998, of which 437 were positive (81%). We then performed a validation study in a subsample of the population using plaque reduction neutralization (PRN) to assess misclassification error. This resulted in a corrected estimate of the prevalence of immunity to measles of 96% (95% CI: 92-100%). The military vaccinates a percentage of recruits who are likely to be immune if more sensitive testing, such as PRN, was used.
Subject(s)
Antibodies, Viral/blood , Enzyme-Linked Immunosorbent Assay , Measles/diagnosis , Measles/immunology , Military Personnel , Enzyme-Linked Immunosorbent Assay/standards , Humans , Measles/epidemiology , Measles virus/immunology , Seroepidemiologic Studies , United States/epidemiology , VaccinationABSTRACT
Recent mumps outbreaks in older vaccinated populations were caused primarily by genotype G viruses, which are phylogenetically distinct from the genotype A vaccine strains used in the countries affected by the outbreaks. This finding suggests that genotype A vaccine strains could have reduced efficacy against heterologous mumps viruses. The remote history of vaccination also suggests that waning immunity could have contributed to susceptibility. To examine these issues, we obtained consecutive serum samples from children at different intervals after vaccination and assayed the ability of these samples to neutralize the genotype A Jeryl Lynn mumps virus vaccine strain and a genotype G wild-type virus obtained during the mumps outbreak that occurred in the United States in 2006. Although the geometric mean neutralizing antibody titers against the genotype G virus were approximately one-half the titers measured against the vaccine strain, and although titers to both viruses decreased with time after vaccination, antibody induced by immunization with the Jeryl Lynn mumps vaccine strain effectively neutralized the outbreak-associated virus at all time points tested.
Subject(s)
Antibodies, Viral/immunology , Mumps Vaccine/administration & dosage , Mumps Vaccine/immunology , Mumps virus/immunology , Mumps/virology , Antibody Formation , Child , Child, Preschool , Disease Outbreaks/prevention & control , Humans , Immunization , Measles-Mumps-Rubella Vaccine/administration & dosage , Measles-Mumps-Rubella Vaccine/immunology , Measles-Mumps-Rubella Vaccine/standards , Mumps/epidemiology , Mumps/immunology , Mumps Vaccine/standards , Mumps virus/classification , Neutralization Tests , Treatment Outcome , Vaccines, Combined/immunology , Vaccines, Combined/standardsABSTRACT
BACKGROUND: Clinical trials of measles vaccination administered as aerosol are planned with the aim of obtaining licensure. Measles antibody levels will be measured using the plaque reduction neutralization test (PRNT) to assess antibody responses as a surrogate marker of efficacy. METHODS: A working group examined laboratory protocols for measles PRNT in use at three reference centres and agreed to a standardised procedure, which was subsequently validated. RESULTS: Assay validation showed quantitative results varied approximately threefold both within and between assays. The lower limit of detection was approximately 20milliInternational Units/mL. CONCLUSIONS: A standardised laboratory protocol for measles PRNT was established and validated for use in clinical trials of aerosolized measles vaccines.
Subject(s)
Antibodies, Viral/immunology , Measles Vaccine/immunology , Neutralization Tests/standards , Aerosols , Animals , Chlorocebus aethiops , Statistics as Topic , Vaccination , Vero Cells , Viral Plaque AssayABSTRACT
It has been shown previously that the fusion glycoprotein of human respiratory syncytial virus (RSV-F) interacts with cellular heparan sulfate. Synthetic overlapping peptides derived from the F-protein sequence of RSV subtype A (strain A2) were tested for their ability to bind heparin using heparin-agarose affinity chromatography (HAAC). This evaluation identified 15 peptides representing eight linear heparin-binding domains (HBDs) located within F1 and F2 and spanning the protease cleavage activation site. All peptides bound to Vero and A549 cells, and binding was inhibited by soluble heparins and diminished by either enzymatic treatment to remove cell surface glycosaminoglycans or by treatment with sodium chlorate to decrease cellular sulfation. RSV-F HBD peptides were less likely to bind to glycosaminoglycan-deficient CHO-745 cells than parental CHO-K1 cells that express these molecules. Three RSV-F HBD peptides (F16, F26, and F55) inhibited virus infectivity; two of these peptides (F16 and F55) inhibited binding of virus to Vero cells, while the third (F26) did not. These studies provided evidence that two of the linear HBDs mapped by peptides F16 and F55 may mediate one of the first steps in the attachment of virus to cells while the third, F26, inhibited infectivity at a postattachment step, suggesting that interactions with cell surface glycosaminoglycans may play a role in infectivity of some RSV strains.