Development and application of a multiplex assay for the simultaneous measurement of antibody responses elicited by common childhood vaccines

Antibody Persistence Following Administration of a Hexavalent DTwP-IPV-HB-PRP~T Vaccine Versus Separate DTwP-HB-PRP~T and IPV Vaccines and Safety and Immunogenicity of a Booster Dose of DTwP-IPV-HB-PRP~T Administered With an MMR Vaccine in Healthy Infants in India

BACKGROUND

Antibody persistence of a whole-cell pertussis-containing hexavalent vaccine (DTwP-IPV-HB-PRP~T) and its co- or sequential administration with measles, mumps, rubella (MMR) vaccine were evaluated.

METHODS

Phase III, open-label, randomized, multicenter study in India. Healthy toddlers 12-24 months of age who had received DTwP-IPV-HB-PRP~T or separate DTwP-HB-PRP~T+IPV primary vaccination at 6-8, 10-12 and 14-16 weeks of age received a DTwP-IPV-HB-PRP~T booster concomitantly with MMR (N = 336) or 28 days before MMR (N = 340). Participants had received a first dose of measles vaccine. Immunogenicity assessment used validated assays and safety was by parental reports. All analyses were descriptive.

RESULTS

All participants had prebooster anti-T ≥0.01 IU/mL and anti-polio 1 and 3 ≥8 1/dil, and ≥96.5% had anti-D ≥0.01 IU/mL, anti-HBs ≥10 mIU/mL, anti-polio 2 ≥8 1/dil and anti-PRP ≥0.15 µg/mL; for pertussis, antibody persistence was similar in each group. Postbooster immunogenicity for DTwP-IPV-HB-PRP~T was similar for each antigen in each group: ≥99.5% of participants had anti-D ≥0.01 IU/mL, anti-T ≥0.01 IU/mL, anti-polio 1, 2 and 3 >8 1/dil, anti-HBs ≥10 mIU/mL and anti-PRP ≥1 µg/mL; for pertussis, vaccine response was similar in each group [72.0%-75.9% (anti-PT), 80.8%-81.4% (anti-FIM), 77.6%-79.5% (anti-PRN), 78.2%-80.8% (anti-FHA)]. There was no difference in MMR immunogenicity between groups, and no difference in DTwP-IPV-HB-PRP~T booster immunogenicity based on the primary series. There were no safety concerns.

CONCLUSIONS

DTwP-IPV-HB-PRP~T antibody persistence was similar to licensed comparators. Booster immunogenicity was robust after DTwP-IPV-HB-PRP~T with or without MMR, and MMR immunogenicity was not affected by coadministration with DTwP-IPV-HB-PRP~T.

CLINICAL TRIALS REGISTRY INDIA NUMBER

CTRI/2020/04/024843.

Immunogenicity and Safety of a Hexavalent DTwP-IPV-HB-PRP~T Vaccine Versus Separate DTwP-HB-PRP~T, bOPV, and IPV Vaccines Administered at 2, 4, 6 Months of Age Concomitantly With Rotavirus and Pneumococcal Conjugate Vaccines in Healthy Infants in Thailand

BACKGROUND

This study investigated the immunogenicity and safety of a fully liquid, hexavalent, diphtheria (D)-tetanus (T)-whole-cell pertussis (wP)-inactivated poliovirus (IPV)-hepatitis B (HB)-Haemophilus influenzae b (PRP-T) vaccine compared to licensed DTwP-HB-PRP~T, IPV, and bivalent oral poliovirus (bOPV) vaccines following co-administration with other pediatric vaccines [pneumococcal conjugate vaccine (PCV13) and rotavirus vaccine].

METHODS

Phase III, randomized, open-label study in Thailand. Healthy infants received DTwP-IPV-HB-PRP~T at 2, 4 and 6 months of age (N = 228), or DTwP-HB-PRP~T and bOPV (2, 4 and 6 months of age) and IPV (4 months of age) (N = 231). All participants received PCV13 (2, 4 and 6 months of age) and rotavirus vaccine (2 and 4 months of age). Immunogenicity for all antigens was assessed using validated assays, and noninferiority post-third dose was evaluated for anti-D, anti-T, anti-pertussis [anti-pertussis toxin (anti-PT) and anti-fimbriae 2/3 (anti-FIM)], anti-polio 1, 2, 3, anti-HB, and anti-PRP~T. Safety was assessed using parental reports.

RESULTS

Noninferiority was demonstrated for each antigen, and overall noninferiority of DTwP-IPV-HB-PRP~T versus DTwP-HB-PRP~T+bOPV+IPV was concluded. Similarity in each group was observed for the GMC ratio for antirotavirus antibodies (20.9 and 17.3, respectively) and anti-PCV13 antibodies (range: 8.46-32.6 and 7.53-33.1, respectively). Two serious adverse events were related to DTwP-IPV-HB-PRP~T (febrile convulsion and acute febrile illness) and 1 was related to DTwP-HB-PRP~T+bOPV+IPV (febrile seizure), but overall there were no safety concerns with similar rates of participants experiencing solicited (99.1% and 98.3%) and unsolicited (19.3% and 19.5%) adverse events in each group.

CONCLUSIONS

This study confirmed the suitability of DTwP-IPV-HB-PRP~T primary series vaccination in combination with rotavirus and PCV13 vaccines.

Immunogenicity of a liquid hexavalent DTaP-IPV-HB-PRP∼T vaccine after primary and booster vaccination of term and preterm infants born to women vaccinated with Tdap during pregnancy

BACKGROUND

Vaccination during pregnancy with tetanus, diphtheria, acellular pertussis (aP) (Tdap) antigens is important for early protection of newborn infants against pertussis, particularly for preterm infants. This study evaluated the effect of Tdap vaccination during pregnancy on the immunogenicity of a diphtheria (D), tetanus (T), aP, inactivated poliovirus (IPV), hepatitis B (HB), and Haemophilus influenzae type b (PRP ∼ T) vaccine in term and preterm populations.

METHODS

A prospective, observational study (NCT02511327) recruited women and their infants based on delivery (term or preterm) and vaccination status (vaccinated with a Tdap vaccine [Boostrix™, GlaxoSmithKline] during pregnancy or not vaccinated in the last 5 years). All infants received licensed DTaP-IPV-HB-PRP ∼ T (Hexyon™, Sanofi) (8, 12, 16 week primary series and booster at 13 months of age [preterm infants] or 15 months of age [term infants]). Immunogenicity was evaluated using validated assays. Data were pooled into term (N = 127) and preterm infants (N = 105), and infants of women who received a Tdap vaccine during pregnancy (N = 199) or not (N = 33).

RESULTS

Before primary vaccination, antibody levels were higher for term than preterm infants for anti-D, anti-polio 1, 2, 3, anti-PT, anti-FHA, and anti-PRP, and similar for anti-HBs and anti-T. At this time, infants of Tdap-vaccinated women had higher anti-D, anti-T, anti-PT, anti-FHA, and anti-PRP antibody levels than infants of Tdap-unvaccinated women; anti-HBs and anti-polio antibody levels were similar in both groups. Post-primary, pre-booster, and post-booster, there were only small differences in seroprotection rates (anti-D, anti-T, anti-polio 1, 2, 3, anti-HBs, anti-PRP) and seroconversion rates (anti-PT, anti-FHA), except for anti-HBs ≥ 10 mIU/mL and anti-PRP ≥ 0.15 µg/mL post-primary vaccination (higher for term [98.31 % and 90.91 %, respectively] versus preterm infants [89.80 % and 79.41 %, respectively]).

CONCLUSIONS

These data support the use of DTaP-IPV-HB-PRP ∼ T vaccine for primary and booster vaccination in term and preterm born infants and in infants born to Tdap-vaccinated or Tdap-unvaccinated women.

Effects of concurrent administration of modified live viral vaccines with RB51 on immune responses to RB51

Brucella abortus is a gram negative, zoonotic pathogen that can cause abortions and stillbirths in the cattle industry and has contributed to significant economic losses to cow-calf producers. Cell mediated immunity (CMI) is an important component of the immune response associated with protection against Brucella abortus and other intracellular pathogens. Brucellosis and viral modified live vaccines (vMLV) are licensed individually but may be used concurrently under field conditions. Peripheral blood mononuclear cells (PBMC) from non-vaccinated cattle and cattle vaccinated with either Brucella abortus strain RB51, a vMLV or both RB51 and a vMLV vaccine were isolated. The frequency of CD4⁺, CD8⁺ and γδ⁺ T cell populations within PBMC, and the frequency of interferon gamma (IFN-γ) production within these cell types was characterized via flow-cytometry. The goal of this study was to characterize immune responses to RB51 vaccination and determine the effect of concurrent vaccine administration. Although immune responses were greatest in PBMC from cattle vaccinated with only RB51, cattle vaccinated with both RB51 and vMLV demonstrated measurable T cell responses associated with protective immunity. Data suggests a lack of significant biological differences between the groups in protective immune responses. Collectively, our data demonstrated a lack of vaccine interference following concurrent administration of vMLV and RB51. Although concurrent administration of individually licensed vaccines may influence immune responses and contribute to vaccine interference, potential vaccine combinations should be evaluated for biological effects.

Cellular assays to evaluate B-cell function

Inborn errors of immunity (IEI) that present with recurrent infections are largely due to antibody (Ab) deficiencies. Therefore, assessment of the B-cell and Ab compartment is a major part of immunologic evaluation. Here we provide an overview about cellular assays used to study B-cell function and focus on lymphocyte proliferation assay (LPA), opsonophagocytic assay (OPA), and the Enzyme-linked Immunosorbent Spot Assay (ELISPOT) including clinical applications and limitations of these techniques. LPAs assess ex-vivo cell proliferation in response to various stimuli. Clinically available LPAs utilize peripheral blood mononuclear cells and mostly assess T-cell proliferation with pokeweed mitogen considered the most B-cell specific stimulus. In the research setting, isolating B cells or using more B-cell specific stimuli such as CD40L with IL-4/IL-21 or the TLR9 ligand CpG can more specifically capture the proliferative ability of B cells. OPAs are functional in-vitro killing assays used to evaluate the ability of IgG Ab to induce phagocytosis applied when assessing the potency of vaccine candidates or along with avidity assays to evaluate the quality of secreted IgG. The B-cell ELISPOT assesses Ab production at a cellular level and can characterize the Ab response of particular B-cell subtypes. It can be used in patients on IgG therapy by capturing specific Abs produced by individual B cells, which is not affected by exogenous IgG from plasma donors, and when assessing the vaccine response in patients on immunomodulatory drugs that can affect memory B-cell function. Emerging approaches that are only available in research settings are also briefly introduced.

Safety and immunogenicity of an indigenously developed tetanus toxoid, diphtheria toxoid, and acellular pertussis vaccine (Tdap) in adults, adolescents, and children in India

BACKGROUND

This study assessed safety and immunogenicity of Serum Institute of India Pvt Ltd (SIIPL)'s tetanus toxoid (TT), diphtheria toxoid (DT), and acellular pertussis booster vaccine (Tdap).

RESEARCH DESIGN AND METHODS

In this Phase II/III, multicenter, randomized, active-controlled, open-label study, 1500 healthy individuals, aged 4-65 years, were randomized to receive a single dose of SIIPL Tdap or comparator Tdap vaccine (Boostrix®; GlaxoSmithKlines, India). Adverse events (AEs) during initial 30 minutes, 7-day, 30-day post-vaccination were assessed. Blood samples were taken before and 30 days post-vaccination for immunogenicity assessment.

RESULTS

No significant differences in incidence of local and systemic solicited AEs were observed between the two groups; no vaccine-related serious AEs were reported. SIIPL Tdap was non-inferior to comparator Tdap in achieving booster responses to TT and DT in 75.2% and 70.8% of the participants, respectively, and to pertussis toxoid (PT), pertactin (PRN), and filamentous hemagglutinin (FHA) in 94.3%, 92.6%, and 95.0% of the participants, respectively. Anti-PT, anti-PRN, and anti-FHA antibody geometric mean titers in both the groups, were significantly higher post-vaccination compared to pre-vaccination.

CONCLUSIONS

Booster vaccination with SIIPL Tdap was non-inferior to comparator Tdap with respect to immunogenicity against tetanus, diphtheria, and pertussis and was well tolerated.

Development of a bead-based multiplex immunoassay for simultaneous quantitative detection of IgG serum antibodies against seven vaccine-preventable diseases

Serosurveillance and seroprevalence studies should be carried out to monitor vaccine-preventable diseases. Multiplex immunoassay (MIA) systems are useful tools for this purpose, allowing the simultaneous quantitative detection of antibodies in one small serum sample, which presents an advantage over conventional methods, such as enzyme-linked immunosorbent assays (ELISAs). Therefore, we developed a multiplex immunoassay for the measurement of antibodies against seven vaccine-preventable infections (measles, rubella, mumps, tetanus, diphtheria, pertussis and Haemophilus influenza type b (Hib) infection). In our multiplex system, heterologous inhibition generally did not exceed 10%, while homologous inhibition varied between 90 and 98%. The intra- and inter-assay variability was ≤11%. The results of in-house MIA showed satisfactory correlation with commercial ELISAs, with Spearman correlation coefficients from 0.90 to 0.98. At the cut-off values defined for our MIA the serostatus can be determined with high sensitivity (89-100%) and specificity (92-98%). Thus, the developed in-house MIA represents a feasible alternative to conventional ELISAs and could be used for large-scale serosurveillance/seroprevalence studies of vaccine-preventable diseases.

Congenital Human Cytomegalovirus Infection Is Associated With Decreased Transplacental IgG Transfer Efficiency Due to Maternal Hypergammaglobulinemia

BACKGROUND

Placentally transferred maternal immunoglobulin G (IgG) protects against pathogens in early life, yet vertically transmitted infections can interfere with transplacental IgG transfer. Although human cytomegalovirus (HCMV) is the most common placentally-transmitted viral infection worldwide, the impact of congenital HCMV (cCMV) infection on transplacental IgG transfer has been underexplored.

METHODS

We evaluated total and antigen-specific maternal and cord blood IgG levels and transplacental IgG transfer efficiency in a US-based cohort of 93 mother-infant pairs including 27 cCMV-infected and 66 cCMV-uninfected pairs, of which 29 infants were born to HCMV-seropositive nontransmitting mothers and 37 to HCMV-seronegative mothers. Controls were matched on sex, race/ethnicity, maternal age, and delivery year.

RESULTS

Transplacental IgG transfer efficiency was decreased by 23% (95% confidence interval [CI] 10-36%, P = .0079) in cCMV-infected pairs and 75% of this effect (95% CI 28-174%, P = .0085) was mediated by elevated maternal IgG levels (ie, hypergammaglobulinemia) in HCMV-transmitting women. Despite reduced transfer efficiency, IgG levels were similar in cord blood from infants with and without cCMV infection.

CONCLUSIONS

Our results indicate that cCMV infection moderately reduces transplacental IgG transfer efficiency due to maternal hypergammaglobulinemia; however, infants with and without cCMV infection had similar antigen-specific IgG levels, suggesting comparable protection from maternal IgG acquired via transplacental transfer.

Safety and immunogenicity of a hexavalent DTwP-IPV-HB-PRP∼T vaccine versus separate DTwP-HB-PRP∼T and IPV vaccines in healthy infants in India

Background

Multivalent vaccines containing whole-cell pertussis (wP) antigens combined with established diphtheria (D), tetanus (T), hepatitis B (HB), Haemophilus influenzae type b (Hib), and inactivated poliomyelitis (IPV) antigens allow the provision of a high-quality, affordable DTwP-IPV-HB-PRP∼T vaccine.

Methods

Phase I/II, randomized, active-controlled, open-label study in healthy toddlers (Cohort I) and infants (Cohort II). Toddlers in Cohort I who had completed primary series D, T, P, HB, Hib, and polio vaccination received a booster dose of DTwP-IPV-HB-PRP∼T (N = 30) or DTwP-HB-PRP∼T + IPV (N = 15) vaccines at 15–18 months of age. After satisfactory review of safety data in Cohort I, infants in Cohort II received DTwP-IPV-HB-PRP∼T (N = 100) or DTwP-HB-PRP∼T + IPV (N = 50) at 6–8, 10–12, and 14–16 weeks of age. All infants in Cohort II had received previous oral polio and HB vaccines per country recommendations.

Results

Booster and primary series vaccinations were well tolerated with no clinically significant differences between vaccine groups. Most adverse events were mild and resolved spontaneously; there were no vaccine-related serious adverse events and no deaths. In both vaccine groups, anti-D, anti-T, anti-HB, anti-Hib, and anti-polio 1, 2, and 3 seroprotection was 100% post-booster and post-primary series. For the pertussis antigens, booster response rate was > 86% in both groups. For the primary series, vaccine response rate was slightly higher for DTwP-IPV-HB-PRP∼T than DTwP-HB-PRP∼T + IPV for anti-PT (80.2% and 70.8%) and anti-FHA (81.3% and 68.8%), slightly lower for anti-PRN (72.5% and 81.3%), and similar in each group for anti-FIM (95.6% and 97.9%).

Conclusions

This study demonstrated a good safety and immunogenicity profile of the hexavalent DTwP-IPV-HB-PRP∼T vaccine for infant primary series vaccination at 6–8, 10–12, and 14–16 weeks of age and booster vaccination at 15–18 months of age and supported progression to the next development phase.

HIV envelope antigen valency on peptide nanofibers modulates antibody magnitude and binding breadth

A major challenge in developing an effective vaccine against HIV-1 is the genetic diversity of its viral envelope. Because of the broad range of sequences exhibited by HIV-1 strains, protective antibodies must be able to bind and neutralize a widely mutated viral envelope protein. No vaccine has yet been designed which induces broadly neutralizing or protective immune responses against HIV in humans. Nanomaterial-based vaccines have shown the ability to generate antibody and cellular immune responses of increased breadth and neutralization potency. Thus, we have developed supramolecular nanofiber-based immunogens bearing the HIV gp120 envelope glycoprotein. These immunogens generated antibody responses that had increased magnitude and binding breadth compared to soluble gp120. By varying gp120 density on nanofibers, we determined that increased antigen valency was associated with increased antibody magnitude and germinal center responses. This study presents a proof-of-concept for a nanofiber vaccine platform generating broad, high binding antibody responses against the HIV-1 envelope glycoprotein.

Pediatric Vaccine Hesitancy and the Utilization of Antibody Measurements: A Novel Strategy with Implications for COVID 19

Vaccine hesitancy is a well researched area with implications for both public health and the health of children and their families The factors leading to vaccine hesitancy are often complex and involve fear of the healthcare system and the process of vaccine development, cultural viewpoints and experiences. Pediatric patients often rely on parental guidance and decision making, and this may result in a lack of immunization for some children. The availability of the COVID 19 vaccine has been widely anticipated, yet not all individuals will seek the vaccine. Once vaccines are available for children under the age of 16 years, this long-standing pediatric management issue may again emerge and impact public health. The clinical trial efficacy and safety data for children and adolescents less than 16 years of age are not yet available. A traditional approach is to discuss the concerns of the parent in relationship to presentation and review of American Association of Pediatrics (AAP) and CDC guidelines in the framework of medical and scientific explanations. This includes the presentation of efficacy and safety data. Therefore, the use of lab-based antibody testing adds scientific evidence and emphasizes the need for vaccination against SARS CoV-2 and other pathogens. The purpose of this commentary is to propose lab-based testing as a potential adjunctive strategy in addressing this public health concern. Further study of a pediatric population is required to assess the impact of the selective use of lab-based testing in improving vaccination rates among a pediatric population.

Immunogenicity and safety of a hexavalent pediatric vaccine in HIV-exposed infected and uninfected infants in Republic of South Africa

Human immunodeficiency virus (HIV)-exposed infants may be at increased risk of vaccine-preventable disease. This study was conducted as a post-licensure commitment in this population to evaluate the primary series, antibody persistence, and booster response to a licensed fully liquid hexavalent vaccine containing diphtheria (D), tetanus (T), acellular pertussis (aP), inactivated poliovirus (IPV), hepatitis B (HB), and Haemophilus influenzae type b antigens (PRP~T). This was a Phase III, open-label, randomized study conducted at a single center in the Republic of South Africa. The DTaP-IPV-HB-PRP~T vaccine was administered to HIV-exposed infected (Group A: N = 14) and HIV-exposed uninfected (Group B: N = 50) infants as a 6, 10, 14 week primary series with a toddler booster at 15–18 months of age. Immunogenicity of each antigen was measured using validated assays and vaccine reactogenicity was recorded using diary cards. The low number of HIV-exposed infected participants, due to widespread pre- and peri-natal retroviral treatment, meant that between-group comparisons should be treated with caution. In each group, primary series and booster immune seroprotection rates were strong, and pre-booster antibody persistence was good, although anti-HBs ≥10 mIU/mL in Group A was 78.6% post-primary series, 58.3% pre-booster, and 75.0% post-booster. There were no safety concerns. In conclusion, primary series and booster vaccination of the DTaP-IPV-HB-PRP~T vaccine were immunogenic and safe in HIV-exposed infected and uninfected infants. These results were comparable to historical data in healthy infants and toddlers.

How much does it cost to measure immunity? A costing analysis of a measles and rubella serosurvey in southern Zambia

Background

Serosurveys are a valuable surveillance tool because they provide a more direct measure of population immunity to infectious diseases, such as measles and rubella, than vaccination coverage estimates. However, there is concern that serological surveys are costly. We adapted a framework to capture the costs associated with conducting a serosurvey in Zambia.

Methods

We costed a nested serosurvey in Southern Province, Zambia that collected dried blood spots from household residents in a post-campaign vaccine coverage survey. The financial costs were estimated using an ingredients-based costing approach. Inputs included personnel, transportation, field consumable items, social mobilization, laboratory supplies, and capital items, and were classified by serosurvey function (survey preparation, data collection, biospecimen collection, laboratory testing, and coordination). Inputs were stratified by whether they were applicable to surveys in general or attributable specifically to serosurveys. Finally, we calculated the average cost per cluster and participant.

Results

We estimated the total nested serosurvey cost was US $68,558 to collect dried blood spots from 658 participants in one province in Zambia. A breakdown of the cost by serosurvey phase showed data collection accounted for almost one third of the total serosurvey cost (32%), followed by survey preparation (25%) and biospecimen collection (20%). Analysis by input categories indicated personnel costs were the largest contributing input to overall serosurvey costs (51%), transportation was second (23%), and field consumables were third (9%). By combining the serosurvey with a vaccination coverage survey, there was a savings of $43,957. We estimated it cost $4,285 per average cluster and $104 per average participant sampled.

Conclusions

Adding serological specimen collection to a planned vaccination coverage survey provided a more direct measurement of population immunity among a wide age group but increased the cost by approximately one-third. Future serosurveys could consider ways to leverage existing surveys conducted for other purposes to minimize costs.

Efficiency of placental transfer of vaccine-elicited antibodies relative to prenatal Tdap vaccination status

Administration of vaccines during pregnancy provides maternal protection against infectious diseases. This protection is extended to their infants during the first months of life, as pathogen-specific antibodies formed in response to maternal vaccination are transferred across the placenta to the fetus. Notably, Tdap (tetanus-diphtheria-acellular pertussis) vaccination booster is routinely administered to pregnant women both to prevent neonatal tetanus and to ensure that infants have protective levels of pertussis antibodies until they are able to establish their own vaccine-induced levels. Whether infant protection through maternal immunization is merely due to an increase in maternal antibody levels or whether maternal immunization enhances the transfer of vaccine-specific antibodies is unclear. Moreover, the potential impact of prenatal vaccinations on the transplacental transfer of other antibodies, such as antibodies raised as a result of infections or other vaccines administered prior to pregnancy, has not been studied. The goal of this study was to define the impact of maternal vaccination on IgG transplacental transfer efficiency. We analyzed antigen-specific antibody populations and IgG subclass distribution in maternal and cord blood samples from 58 mother-infant pairs. All women received the seasonal inactivated influenza vaccine during pregnancy and 25 women received the Tdap vaccine during the second or third trimester of gestation. Prenatal Tdap vaccination did not impact the efficiency of IgG transplacental transfer; however, it was associated with higher maternal and infant vaccine-elicited Tdap-specific antibody levels, and with a higher proportion of infants with protective levels of antibodies, especially against diphtheria. There was also no difference in the IgG transplacental transfer rate of antibodies against non-Tdap vaccines between the two groups of women. Our results confirm previous reports demonstrating the benefits of prenatal Tdap immunization and indicate that this strategy does not impede the transplacental transfer of other antibodies that are also important for infant protection.

Pandemic influenza A(H1N1pdm09) vaccine induced high levels of influenza-specific IgG and IgM antibodies as analyzed by enzyme immunoassay and dual-mode multiplex microarray immunoassay methods

Influenza A viruses continue to circulate throughout the world as yearly epidemics or occasional pandemics. Influenza infections can be prevented by seasonal multivalent or monovalent pandemic vaccines. In the present study, we describe a novel multiplex microarray immunoassay (MAIA) for simultaneous measurement of virus-specific IgG and IgM antibodies using Pandemrix-vaccinated adult sera collected at day 0 and 28 and 180 days after vaccination as the study material. MAIA showed excellent correlation with a conventional enzyme immunoassay (EIA) in both IgG and IgM anti-influenza A antibodies and good correlation with hemagglutination inhibition (HI) test. Pandemrix vaccine induced 5-30 fold increases in anti-H1N1pdm09 influenza antibodies as measured by HI, EIA or MAIA. A clear increase in virus-specific IgG antibodies was found in 93-97% of vaccinees by MAIA and EIA. Virus-specific IgM antibodies were found in 90-92% of vaccinees by MAIA and EIA, respectively and IgM antibodies persisted for up to 6 months after vaccination in 55-62% of the vaccinees. Pandemic influenza vaccine induced strong anti-influenza A IgG and IgM responses that persisted several months after vaccination. MAIA was demonstrated to be an excellent method for simultaneous measurement of antiviral IgG and IgM antibodies against multiple virus antigens. Thus the method is well suitable for large scale epidemiological and vaccine immunity studies.

Efficient transplacental IgG transfer in women infected with Zika virus during pregnancy

Zika virus (ZIKV) is a newly-identified infectious cause of congenital disease. Transplacental transfer of maternal IgG to the fetus plays an important role in preventing many neonatal infections. However, antibody transfer may also have negative consequences, such as mediating enhancement of flavivirus infections in early life, or trafficking of virus immune complexes to the fetal compartment. ZIKV infection produces placental pathology which could lead to impaired IgG transfer efficiency as occurs in other maternal infections, such as HIV-1 and malaria. In this study, we asked whether ZIKV infection during pregnancy impairs transplacental transfer of IgG. We enrolled pregnant women with fever or rash in a prospective cohort in Vitoria, Brazil during the recent ZIKV epidemic. ZIKV and dengue virus (DENV)-specific IgG, ZIKV and DENV neutralizing antibodies, and routine vaccine antigen-specific IgG were measured in maternal samples collected around delivery and 20 paired cord blood samples. We concluded that 8 of these mothers were infected with ZIKV during pregnancy and 12 were ZIKV-uninfected. The magnitude of flavivirus-specific IgG, neutralizing antibody, and vaccine-elicited IgG were highly correlated between maternal plasma and infant cord blood in both ZIKV-infected and -uninfected mother-infant pairs. Moreover, there was no difference in the magnitude of plasma flavivirus-specific IgG levels between mothers and infants regardless of ZIKV infection status. Our data suggests that maternal ZIKV infection during pregnancy does not impair the efficiency of placental transfer of flavivirus-specific, functional, and vaccine-elicited IgG. These findings have implications for the neonatal outomes of maternal ZIKV infection and optimal administration of antibody-based ZIKV vaccines and therapeutics.

Mercury Exposure and Poor Nutritional Status Reduce Response to Six Expanded Program on Immunization Vaccines in Children: An Observational Cohort Study of Communities Affected by Gold Mining in the Peruvian Amazon

Background: Poor nutritional status combined with mercury exposure can generate adverse child health outcomes. Diet is a mediator of mercury exposure and evidence suggests that nutritional status modifies aspects of mercury toxicity. However, health impacts beyond the nervous system are poorly understood. This study evaluates antibody responses to six vaccines from the expanded program on immunization (EPI), including hepatitis B, Haemophilus influenzae type B, measles, pertussis, tetanus, and diphtheria in children with variable hair mercury and malnutrition indicators. Methods: An observational cohort study (n = 98) was conducted in native and non-native communities in Madre de Dios, Peru, a region with elevated mercury exposure from artisanal and small-scale gold mining. Adaptive immune responses in young (3–48 months) and older children (4–8 year olds) were evaluated by vaccine type (live attenuated, protein subunits, toxoids) to account for differences in response by antigen, and measured by total IgG concentration and antibody (IgG) concentrations of each EPI vaccine. Mercury was measured from hair samples and malnutrition determined using anthropometry and hemoglobin levels in blood. Generalized linear mixed models were used to evaluate associations with each antibody type. Results: Changes in child antibodies and protection levels were associated with malnutrition indicators, mercury exposure, and their interaction. Malnutrition was associated with decreased measles and diphtheria-specific IgG. A one-unit decrease in hemoglobin was associated with a 0.17 IU/mL (95% CI: 0.04–0.30) decline in measles-specific IgG in younger children and 2.56 (95% CI: 1.01–6.25) higher odds of being unprotected against diphtheria in older children. Associations between mercury exposure and immune responses were also dependent on child age. In younger children, one-unit increase in log₁₀ child hair mercury content was associated with 0.68 IU/mL (95% CI: 0.18–1.17) higher pertussis and 0.79 IU/mL (95% CI: 0.18–1.70) higher diphtheria-specific IgG levels. In older children, child hair mercury content exceeding 1.2 µg/g was associated with 73.7 higher odds (95% CI: 2.7–1984.3) of being a non-responder against measles and hair mercury content exceeding 2.0 µg/g with 0.32 IU/mL (95% CI: 0.10–0.69) lower measles-specific antibodies. Log₁₀ hair mercury significantly interacted with weight-for-height z-score, indicating a multiplicative effect of higher mercury and lower nutrition on measles response. Specifically, among older children with poor nutrition (WHZ = −1), log₁₀ measles antibody is reduced from 1.40 to 0.43 for low (<1.2 µg/g) vs. high mercury exposure, whereas for children with good nutritional status (WHZ = 1), log₁₀ measles antibody is minimally changed for low vs. high mercury exposure (0.72 vs. 0.81, respectively). Conclusions: Child immune response to EPI vaccines may be attenuated in regions with elevated mercury exposure risk and exacerbated by concurrent malnutrition.

Validation of monoplex assays detecting antibodies against Corynebacterium diphtheriae and Clostridium tetani toxins, rubella virus and parvovirus B19 for incorporation into Multiplex Serology

Serological assays detecting antibodies in serum or plasma samples are useful and versatile instruments to investigate an individual's infection and vaccination history, e.g. for clinical diagnosis, personal risk evaluation, and seroepidemiological studies. Multiplex Serology is a suspension bead array-based high-throughput methodology for simultaneous measurement of antibodies against multiple pathogens in a single reaction vessel, thus economizing sample volume, measurement time, and costs. We developed and validated bead-based pathogen-specific Monoplex Serology assays, i.e. assays including only antigens for the respective pathogen, to detect antibodies against Corynebacterium diphtheriae and Clostridium tetani toxins, rubella virus and parvovirus B19. The developed assays expand the portfolio of existing pathogen-specific bead-based serology assays and can be efficiently incorporated into larger Multiplex Serology panels. The newly developed Monoplex Serology assays consist of only one antigen per infectious agent, expressed as Glutathione S-transferase-fusion proteins in E. coli. Specificity, sensitivity and Cohen's kappa statistics in comparison with routine clinical diagnostic assays were calculated for serum dilutions 1:100 and 1:1000. All pathogen-specific assays were successfully validated at both serum dilutions with the exception of rubella Monoplex Serology which showed impaired sensitivity (57.6%) at dilution 1:1000. Specificities of successfully validated Monoplex Serology assays ranged from 85.6% to 100.0% (median: 91.7%), and sensitivities from 81.3% to 95.8% (median: 90.9%); agreement with the reference assays ranged from substantial to almost perfect (kappa: 0.66-0.86, median: 0.78). Statistical performance and slim assay design enable efficient incorporation of the developed assays into Multiplex Serology.

The use of multiplexing technology in the immunodiagnosis of infectious agents

Traditionally, definitive diagnosis of infectious diseases is made by cultivation of the causative agent, while various antigens and antibodies as biomarkers of various diseases are detected by commercially available ELISA kits. PCR has emerged as a major innovation that greatly accelerated the accumulation of genomic and transcriptomic data, yet it has also revolutionized microbial diagnostics by enabling the detection of pathogen nucleic acid. Despite the advantages of and vast experience in ELISA and PCR, the next generation research and diagnostic tools have to fulfill the requirements of systems and synthetic biology era. Multiplex bead assays hold this promise by providing a more complete multi-parametric picture of the biological phenomenon of interest at a fraction of time, sample volume and cost required for conventional assay systems. To date, numerous multiplex bead assays have been described to detect multiple antigen, antibody and nucleic acid targets of both microbial pathogens and immune response. These assays have been successfully used in diagnostic, cohort screening and research setups.