Publications by authors named "Marjahan Akhtar"

14 Publications

  • Page 1 of 1

Prevalence of COVID-19 in Bangladesh, April to October 2020-a cross-sectional study.

IJID Reg 2021 Dec 14;1:92-99. Epub 2021 Oct 14.

Directorate General of Health Services (DGHS), Dhaka, Bangladesh.

The aim of this study was to estimate the proportion of symptomatic and asymptomatic laboratory-confirmed coronavirus disease 2019 (COVID-19) cases among the population of Bangladesh. A cross-sectional survey was conducted in Dhaka City and other districts of Bangladesh between April 18 and October 12, 2020. A total of 32 districts outside Dhaka were randomly selected, and one village and one mahalla was selected from each district; 25 mahallas were selected from Dhaka City. From each village or mahalla, 120 households were enrolled through systematic random sampling. A total of 44 865 individuals were interviewed from 10 907 households. The majority (70%,  = 31 488) of the individuals were <40 years of age. Almost half of the individuals (49%,  = 21 888) reported more than four members in their household. It was estimated that 12.6% ( = 160) of the households had one or more severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected individuals, among whom 0.9% ( = 404) of individuals had at least one COVID-19-like symptom, at the national level. The prevalence of COVID-19 in the general population was 6.4%. Among the SARS-CoV-2-positive individuals, 87% were asymptomatic. The substantial high number of asymptomatic cases all over Bangladesh suggests that community-level containment and mitigation measures are required to combat COVID-19. Future studies to understand the transmission capability could help to define mitigation and control measures.
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http://dx.doi.org/10.1016/j.ijregi.2021.10.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8516147PMC
December 2021

Seroprevalence of SARS-CoV-2 antibodies in Bangladesh related to novel coronavirus infection.

IJID Reg 2022 Mar 2;2:198-203. Epub 2022 Feb 2.

International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh.

Design: A cross-sectional study was conducted amongst household members in 32 districts of Bangladesh to build knowledge about disease epidemiology and seroepidemiology of coronavirus disease 2019 (COVID-19).

Objective: Antibody responses to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) were assessed in people between April and October 2020.

Results: The national seroprevalence rates of immunoglobulin G (IgG) and IgM were estimated to be 30.4% and 39.7%, respectively. In Dhaka, the seroprevalence of IgG was 35.4% in non-slum areas and 63.5% in slum areas. In areas outside of Dhaka, the seroprevalence of IgG was 37.5% in urban areas and 28.7% in rural areas. Between April and October 2020, the highest seroprevalence rate (57% for IgG and 64% for IgM) was observed in August. IgM antibody was more prevalent in younger participants, while older participants had more frequent IgG seropositivity. Follow-up specimens from patients with COVID-19 and their household members suggested that both IgG and IgM seropositivity increased significantly at day 14 and day 28 compared with day 1 after enrolment. : SARS-CoV-2 had spread extensively in Bangladesh by October 2020. This highlights the importance of monitoring seroprevalence data, particularly with the emergence of new SARS-CoV-2 variants over time.
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http://dx.doi.org/10.1016/j.ijregi.2022.01.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8809641PMC
March 2022

Covishield vaccine induces robust immune responses in Bangladeshi adults.

IJID Reg 2022 Jun 29;3:211-217. Epub 2022 Apr 29.

International Centre for Diarrhoeal Disease Research Bangladesh, Dhaka, Bangladesh.

Objective: To evaluate severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2)-specific antibody responses after Covishield vaccination for 6 months after vaccination.

Design: SARS-CoV-2-specific antibody responses were assessed by enzyme-linked immunosorbent assay of the recombinant receptor-binding domain of SARS-CoV-2 in 381 adults given the Covishield vaccine at baseline (=119), 1 month (=126) and 2 months (=75) after the first dose, 1 month after the second dose (=161), and monthly for 3 additional months.

Results: Over 51% of participants were seropositive at baseline (before vaccination with Covishield), and almost all participants (159/161) became seropositive 1 month after the second dose. Antibody levels peaked 1 month after receipt of the second dose of vaccine, and decreased by 4 months after the first dose; the lowest responses were found 6 months after the first dose, although antibody responses and responder frequencies remained significantly higher compared with baseline (<0.0001). Compared with younger participants, older participants had lower antibody responses 6 months after the first dose of vaccine (<0.05). Participants who had previous SARS-CoV-2 infection showed robust higher antibody responses after vaccination.

Conclusions: These findings help to elucidate the longevity of vaccine-specific antibody responses following vaccination with Covishield, and provide information relevant to the planning of booster doses after the initial two doses of vaccine.
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http://dx.doi.org/10.1016/j.ijregi.2022.04.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9050186PMC
June 2022

Transmission of SARS-CoV-2 in the Population Living in High- and Low-Density Gradient Areas in Dhaka, Bangladesh.

Trop Med Infect Dis 2022 Mar 25;7(4). Epub 2022 Mar 25.

Programme for Emerging Infections, Infectious Diseases Division, icddr,b, Dhaka 1212, Bangladesh.

Community transmission of SARS-CoV-2 in densely populated countries has been a topic of concern from the beginning of the pandemic. Evidence of community transmission of SARS-CoV-2 according to population density gradient and socio-economic status (SES) is limited. In June-September 2020, we conducted a descriptive longitudinal study to determine the community transmission of SARS-CoV-2 in high- and low-density areas in Dhaka city. The Secondary Attack Rate (SAR) was 10% in high-density areas compared to 20% in low-density areas. People with high SES had a significantly higher level of SARS-CoV-2-specific Immunoglobulin G (IgG) antibodies on study days 1 ( = 0.01) and 28 ( = 0.03) compared to those with low SES in high-density areas. In contrast, the levels of seropositivity of SARS-CoV-2-specific Immunoglobulin M (IgM) were comparable ( > 0.05) in people with high and low SES on both study days 1 and 28 in both high- and low-density areas. Due to the similar household size, no differences in the seropositivity rates depending on the population gradient were observed. However, people with high SES showed higher seroconversion rates compared to people with low SES. As no difference was observed based on population density, the SES might play a role in SARS-CoV-2 transmission, an issue that calls for further in-depth studies to better understand the community transmission of SARS-CoV-2.
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http://dx.doi.org/10.3390/tropicalmed7040053DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9030026PMC
March 2022

SARS-CoV-2 Seroprevalence before Delta Variant Surge, Chattogram, Bangladesh, March-June 2021.

Emerg Infect Dis 2022 02;28(2):429-431

A March-June 2021 representative serosurvey among Sitakunda subdistrict (Chattogram, Bangladesh) residents found an adjusted prevalence of severe acute respiratory syndrome coronavirus 2 antibodies of 64.1% (95% credible interval 60.0%-68.1%). Before the Delta variant surge, most residents had been infected, although cumulative confirmed coronavirus disease incidence was low.
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http://dx.doi.org/10.3201/eid2802.211689DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8798688PMC
February 2022

Disease characteristics and serological responses in patients with differing severity of COVID-19 infection: A longitudinal cohort study in Dhaka, Bangladesh.

PLoS Negl Trop Dis 2022 01 4;16(1):e0010102. Epub 2022 Jan 4.

International Centre for Diarrhoeal Disease Research Bangladesh (icddr,b), Dhaka, Bangladesh).

Background: COVID-19 caused by SARS-CoV-2 ranges from asymptomatic to severe disease and can cause fatal and devastating outcome in many cases. In this study, we have compared the clinical, biochemical and immunological parameters across the different disease spectrum of COVID-19 in Bangladeshi patients.

Methodology/principal Findings: This longitudinal study was conducted in two COVID-19 hospitals and also around the community in Dhaka city in Bangladesh between November 2020 to March 2021. A total of 100 patients with COVID-19 infection were enrolled and classified into asymptomatic, mild, moderate and severe cases (n = 25/group). In addition, thirty age and sex matched healthy participants were enrolled and 21 were analyzed as controls based on exclusion criteria. After enrollment (study day1), follow-up visits were conducted on day 7, 14 and 28 for the cases. Older age, male gender and co-morbid conditions were the risk factors for severe COVID-19 disease. Those with moderate and severe cases of infection had low lymphocyte counts, high neutrophil counts along with a higher neutrophil-lymphocyte ratio (NLR) at enrollment; this decreased to normal range within 42 days after the onset of symptom. At enrollment, D-dimer, CRP and ferritin levels were elevated among moderate and severe cases. The mild, moderate, and severe cases were seropositive for IgG antibody by day 14 after enrollment. Moderate and severe cases showed significantly higher IgM and IgG levels of antibodies to SARS-CoV-2 compared to mild and asymptomatic cases.

Conclusion/significance: We report on the clinical, biochemical, and hematological parameters associated with the different severity of COVID-19 infection. We also show different profile of antibody response against SARS-CoV-2 in relation to disease severity, especially in those with moderate and severe disease manifestations compared to the mild and asymptomatic infection.
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http://dx.doi.org/10.1371/journal.pntd.0010102DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8759637PMC
January 2022

Induction of mucosal and systemic immune responses against the common O78 antigen of an oral inactivated ETEC vaccine in Bangladeshi children and infants.

Vaccine 2022 01 10;40(2):380-389. Epub 2021 Nov 10.

PATH, Washington, DC, USA.

We tested an oral enterotoxigenic Escherichia coli (ETEC) vaccine, ETVAX, consisting of inactivated E. coli overexpressing the most prevalent ETEC colonization factors (CFs) and a toxoid (LCTBA), in Bangladeshi children for capacity to induce mucosal and plasma immune responses against O78 lipopolysaccharide (LPS) expressed on the vaccine strains. The vaccine was given ± double-mutant heat-labile toxin (dmLT) adjuvant. We evaluated the impact of dmLT on anti-O78 LPS immune responses and whether such responses can predict responses against the CFs as a marker for vaccine "take". Two fractionated doses of ETVAX ± different amounts of dmLT were administered biweekly to groups of children 24-59 (n = 125), 12-23 (n = 97) and 6-11 (n = 158) months of age. Immune responses were evaluated in antibody in lymphocyte supernatants (ALS), fecal extracts and plasma. ALS IgA responses against O78 LPS were induced in 44-49% of the children aged 12-59 months. The magnitudes of the ALS responses were significantly higher in children receiving a half-dose (5 × 10 bacteria) of ETVAX ± dmLT than in placebo recipients. <10% of the vaccinees aged 6-11 months mounted ALS responses against O78 LPS. However, 49% of the infants developed fecal secretory IgA responses which were significantly more frequent in those receiving a quarter-dose (2.5 × 10 bacteria) of vaccine + dmLT (62%) compared to a quarter-dose alone (36%). Plasma IgA antibody responses were induced in 80% of older children and 36% of infants. The frequencies of O78 LPS responses in plasma and feces were comparable or higher than against the vaccine CFs in infants. Our findings show that ETVAX induced mucosal and systemic immune responses against O78 LPS in all age groups and that dmLT improved intestinal immune responses among infants. These observations may have implications for more successful use of other oral vaccines based on O antigens in children.
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http://dx.doi.org/10.1016/j.vaccine.2021.10.056DOI Listing
January 2022

Mucosal Immune Responses Against an Oral Enterotoxigenic Escherichia coli Vaccine Evaluated in Clinical Trials.

J Infect Dis 2021 12;224(12 Suppl 2):S821-S828

Infectious Diseases Division of icddr,b, Dhaka, Bangladesh.

Enterotoxigenic Escherichia coli (ETEC) is a leading cause of mortality and morbidity in children in low-income countries. We have tested an oral ETEC vaccine, ETVAX, consisting of inactivated E coli overexpressing the most prevalent colonization factors and a toxoid, LCTBA, administered together with a mucosal adjuvant, double-mutant heat-labile toxin (dmLT), for capacity to induce mucosal immune responses and immunological memory against the primary vaccine antigens, ie, colonization factors, heat-labile toxin B-subunit and O antigen. The studies show that ETVAX could induce strong intestine-derived and/or fecal immune responses in a majority of vaccinated Swedish adults and in different age groups, including infants, in Bangladesh.
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http://dx.doi.org/10.1093/infdis/jiab475DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8687049PMC
December 2021

dmLT Adjuvant Enhances Cytokine Responses to T Cell Stimuli, Whole Cell Vaccine Antigens and Lipopolysaccharide in Both Adults and Infants.

Front Immunol 2021 14;12:654872. Epub 2021 May 14.

Department of Microbiology and Immunology, Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden.

Enhancement of mucosal immune responses in children and infants using novel adjuvants such as double mutant heat labile toxin (dmLT) is an important goal in the enteric vaccine field. dmLT has been shown to enhance mucosal IgA responses to the oral inactivated enterotoxigenic (ETEC) vaccine ETVAX. dmLT can enhance IL-17A production from adult T cells, which may increase the production and secretion of mucosal IgA antibodies. However, the adjuvant mechanism remains to be fully elucidated and might differ between infants and adults due to age-related differences in the development of the immune system. The main objective of this study was to determine how dmLT influences antigen presenting cells and T cells from infants compared to adults, and the role of IL-1β for mediating the adjuvant activity. Peripheral blood mononuclear cells (PBMCs) from Bangladeshi infants (6-11 months) and adults (18-40 years) were stimulated with the mitogen phytohaemagglutinin (PHA), the superantigen Staphylococcal enterotoxin B (SEB), ETVAX whole cell component (WCC) or lipopolysaccharide (LPS) ± dmLT, and cytokine production was measured using ELISA and electrochemiluminescence assays. The adjuvant dmLT significantly enhanced SEB- and PHA-induced IL-17A, but not IFN-γ responses, in PBMCs from both infants and adults. Blocking experiments using an IL-1 receptor antagonist demonstrated the importance of IL-1 signaling for the adjuvant effect. dmLT, ETVAX WCC and LPS induced dose-dependent IL-1β responses of comparable magnitudes in infant and adult cells. Depletion experiments suggested that IL-1β was mainly produced by monocytes. dmLT enhanced IL-1β responses to low doses of WCC and LPS, and the adjuvant effect appeared over a wider dose-range of WCC in infants. dmLT and WCC also induced IL-6, IL-23 and IL-12p70 production in both age groups and dmLT tended to particularly enhance IL-23 responses to WCC. Our results show that dmLT can induce IL-1β as well as other cytokines, which in turn may enhance IL-17A and potentially modulate other immunological responses in both infants and adults. Thus, dmLT may have an important function in promoting immune responses to the ETVAX vaccine, as well as other whole cell- or LPS-based vaccines in infants in low- and middle-income countries.
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http://dx.doi.org/10.3389/fimmu.2021.654872DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8160295PMC
September 2021

Safety and immunogenicity of the oral, inactivated, enterotoxigenic Escherichia coli vaccine ETVAX in Bangladeshi children and infants: a double-blind, randomised, placebo-controlled phase 1/2 trial.

Lancet Infect Dis 2020 02 19;20(2):208-219. Epub 2019 Nov 19.

Gothenburg University Vaccine Research Institute, Department of Microbiology and Immunology, Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden. Electronic address:

Background: Enterotoxigenic Escherichia coli causes diarrhoea, leading to substantial mortality and morbidity in children, but no specific vaccine exists. This trial tested an oral, inactivated, enterotoxigenic E coli vaccine (ETVAX), which has been previously shown to be safe and highly immuongenic in Swedish and Bangladeshi adults. We tested the safety and immunogenicity of ETVAX, consisting of four E coli strains overexpressing the most prevalent colonisation factors (CFA/I, CS3, CS5, and CS6) and a toxoid (LCTBA) administered with or without a double-mutant heat-labile enterotoxin (dmLT) as an adjuvant, in Bangladeshi children.

Methods: We did a randomised, double-blind, placebo-controlled, dose-escalation, age-descending, phase 1/2 trial in Dhaka, Bangladesh. Healthy children in one of three age groups (24-59 months, 12-23 months, and 6-11 months) were eligible. Children were randomly assigned with block randomisation to receive either ETVAX, with or without dmLT, or placebo. ETVAX (half [5·5 × 10 cells], quarter [2·5 × 10 cells], or eighth [1·25 × 10 cells] adult dose), with or without dmLT adjuvant (2·5 μg, 5·0 μg, or 10·0 μg), or placebo were administered orally in two doses 2 weeks apart. Investigators and participants were masked to treatment allocation. The primary endpoint was safety and tolerability, assessed in all children who received at least one dose of vaccine. Antibody responses to vaccine antigens, defined as at least a two-times increase in antibody levels between baseline and post-immunisation, were assessed as secondary endpoints. This trial is registered with ClinicalTrials.gov, NCT02531802.

Findings: Between Dec 7, 2015, and Jan 10, 2017, we screened 1500 children across the three age groups, of whom 430 were enrolled and randomly assigned to the different treatment groups (130 aged 24-59 months, 100 aged 12-23 months, and 200 aged 6-11 months). All participants received at least one dose of vaccine. No solicited adverse events occurred that were greater than moderate in severity, and most were mild. The most common solicited event was vomiting (ten [8%] of 130 patients aged 24-59 months, 13 [13%] of 100 aged 12-23 months, and 29 [15%] of 200 aged 6-11 months; mostly of mild severity), which appeared related to dose and age. The addition of dmLT did not modify the safety profile. Three serious adverse events occurred but they were not considered related to the study drug. Mucosal IgA antibody responses in lymphocyte secretions were detected against all primary vaccine antigens (CFA/I, CS3, CS5, CS6, and the LCTBA toxoid) in most participants in the two older age groups, whereas such responses to four of the five antigens were less frequent and of lower magnitude in infants aged 6-11 months than in older children. Faecal secretory IgA immune responses were recorded against all vaccine antigens in infants aged 6-11 months. 78 (56%) of 139 infants aged 6-11 months who were vaccinated developed mucosal responses against at least three of the vaccine antigens versus 14 (29%) of 49 of the infants given placebo. Addition of the adjuvant dmLT enhanced the magnitude, breadth, and kinetics (based on number of responders after the first dose of vaccine) of immune responses in infants.

Interpretation: The encouraging safety and immunogenicity of ETVAX and benefit of dmLT adjuvant in young children support its further assessment for protective efficacy in children in enterotoxigenic E coli-endemic areas.

Funding: PATH (Bill & Melinda Gates Foundation and the UK's Department for International Development), the Swedish Research Council, and The Swedish Foundation for Strategic Research.
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http://dx.doi.org/10.1016/S1473-3099(19)30571-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6990395PMC
February 2020

Evaluation of the safety and immunogenicity of the oral inactivated multivalent enterotoxigenic Escherichia coli vaccine ETVAX in Bangladeshi adults in a double-blind, randomized, placebo-controlled Phase I trial using electrochemiluminescence and ELISA assays for immunogenicity analyses.

Vaccine 2019 09 22;37(37):5645-5656. Epub 2018 Nov 22.

GUVAX (Gothenburg University Vaccine Research Institute), Dept. of Microbiology and Immunology, Inst. of Biomedicine, University of Gothenburg, Sweden. Electronic address:

The safety and immunogenicity of the second generation oral enterotoxigenic Escherichia coli (ETEC) vaccine ETVAX, consisting of inactivated recombinant E. coli strains over-expressing the colonization factors (CFs) CFA/I, CS3, CS5 and CS6 and the heat labile toxoid LCTBA, were evaluated in Bangladeshi volunteers. To enable analysis of antibody responses against multiple vaccine antigens for subsequent use in small sample volumes from children, a sensitive electrochemiluminescence (ECL) assay for analysis of intestine-derived antibody-secreting cell responses using the antibodies in lymphocyte secretions (ALS) assay was established using Meso Scale Discovery technology. Three groups of Bangladeshi adults (n = 15 per group) received two oral doses of ETVAX with or without double mutant LT (dmLT) adjuvant or placebo in the initial part of a randomized, double-blind, placebo-controlled, age-descending, dose-escalation trial. CF- and LTB-specific ALS and plasma IgA responses were analyzed by ECL and/or ELISA. ETVAX was safe and well tolerated in the adults. Magnitudes of IgA ALS responses determined by ECL and ELISA correlated well (r = 0.85 to 0.98 for the five primary antigens, P < 0.001) and ECL was selected as the ALS readout method. ALS IgA responses against each of the primary antigens were detected in 87-100% of vaccinees after the first and in 100% after the second vaccine dose. Plasma IgA responses against different CFs and LTB were observed in 62-93% and 100% of vaccinees, respectively. No statistically significant adjuvant effect of dmLT on antibody responses to any antigen was detected, but the overall antigenic breadth of the plasma IgA response tended to favor the adjuvanted vaccine when responses to 4 or more or 5 vaccine antigens were considered. Responses in placebo recipients were infrequent and mainly detected against single antigens. The promising results in adults supported testing ETVAX in descending age groups of children. ClinicalTrials.gov Identifier: NCT02531802.
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http://dx.doi.org/10.1016/j.vaccine.2018.11.040DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6717083PMC
September 2019

Kinetics of antibody-secreting cell and fecal IgA responses after oral cholera vaccination in different age groups in a cholera endemic country.

Vaccine 2017 01;35(2):321-328

GUVAX (Gothenburg University Vaccine Research Institute), Dept. of Microbiology and Immunology, Inst. of Biomedicine, University of Gothenburg, Sweden. Electronic address:

Immune responses to oral enteric vaccines in children and infants may be influenced by factors such as age, previous priming with related microorganisms and breast feeding. In this study, we aimed to determine optimal time points to assess immune responses to oral enteric vaccines in different clinical specimens. This was done by investigating antibody secreting cell (ASC) and fecal antibody responses on different days after vaccination using the licensed oral cholera vaccine Dukoral, containing cholera toxin B-subunit (rCTB) and inactivated Vibrio cholerae bacteria, as a model vaccine. Two vaccine doses were given 2weeks apart to infants (6-11months), young children (12-18months), toddlers (19months-5years) and adults in a cholera endemic country (Bangladesh). IgA ASC responses, as determined by the antibodies in lymphocyte supernatant (ALS) assay, plasma IgA and IgG responses and secretory IgA (SIgA) responses in extracts of fecal samples were evaluated 4/5 and 7days after each vaccination. After the first vaccine dose, anti-CTB ALS IgA responses in adults and toddlers were high and comparable on day 5 and 7, while responses were low and infrequent in young children. After the second dose, highest ALS responses were detected on day 5 among the time points studied in all age groups and the responses declined until day 7. In contrast, plasma IgA and IgG anti-CTB responses were high both on day 5 and 7 after the second dose. Fecal SIgA responses in young children and infants were highest on day 7 after the second dose. Our results suggest that ASC/ALS responses to two doses of the oral cholera vaccine Dukoral and related oral vaccines should be analyzed earlier than previously recommended (day 7) at all ages. Fecal antibody responses should preferably be analyzed later than ASC/ALS responses to detect the highest antibody responses.
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http://dx.doi.org/10.1016/j.vaccine.2016.11.055DOI Listing
January 2017

Antibody avidity in humoral immune responses in Bangladeshi children and adults following administration of an oral killed cholera vaccine.

Clin Vaccine Immunol 2013 Oct 7;20(10):1541-8. Epub 2013 Aug 7.

Centre for Vaccine Sciences, International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh.

Antibody avidity for antigens following disease or vaccination increases with affinity maturation and somatic hypermutation. In this study, we followed children and adults in Bangladesh for 1 year following oral cholera vaccination and measured the avidity of antibodies to the T cell-dependent antigen cholera toxin B subunit (CTB) and the T cell-independent antigen lipopolysaccharide (LPS) in comparison with responses in other immunological measurements. Children produced CTB-specific IgG and IgA antibodies of high avidity following vaccination, which persisted for several months; the magnitudes of responses were comparable to those seen in adult vaccinees. The avidity of LPS-specific IgG and IgA antibodies in vaccinees increased significantly shortly after the second dose of vaccine but waned rapidly to baseline levels thereafter. CTB-specific memory B cells were present for only a short time following vaccination, and we did not find significant memory B cell responses to LPS in any age group. For older children, there was a significant correlation between CTB-specific memory T cell responses after the second dose of vaccine and CTB-specific IgG antibody avidity indices over the subsequent year. These findings suggest that vaccination induces a longer-lasting increase in the avidity of antibodies to a T cell-dependent antigen than is measured by a memory B cell response to that antigen and that early memory T cell responses correlate well with the subsequent development of higher-avidity antibodies.
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http://dx.doi.org/10.1128/CVI.00341-13DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3807205PMC
October 2013
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