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Longitudinal analysis of antibody responses to trachoma antigens before and after mass drug administration.

Goodhew EB, Morgan SM, Switzer AJ, Munoz B, Dize L, Gaydos C, Mkocha H, West SK, Wiegand RE, Lammie PJ, Martin DL - BMC Infect. Dis. (2014)

Bottom Line: By age 6, the percentage positive for IgG (96.0%) was much higher than for IgA (74.2%).The percentage decrease in IgA response was much greater than for IgG.However, no instances of seroreversion were observed.

View Article: PubMed Central - HTML - PubMed

Affiliation: Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, USA. hzx3@cdc.gov.

ABSTRACT

Background: Blinding trachoma, caused by the bacteria Chlamydia trachomatis, is a neglected tropical disease targeted for elimination by 2020. A major component of the elimination strategy is mass drug administration (MDA) with azithromycin. Currently, program decisions are made based on clinical signs of ocular infection, but we have been investigating the use of antibody responses for post-MDA surveillance. In a previous study, IgG responses were detected in children lacking clinical evidence of trachoma, suggesting that IgG responses represented historical infection. To explore the utility of serology for program evaluation, we compared IgG and IgA responses to trachoma antigens and examined changes in IgG and IgA post-drug treatment.

Methods: Dried blood spots and ocular swabs were collected with parental consent from 264 1-6 year olds in a single village of Kongwa District, central Tanzania. Each child also received an ocular exam for detection of clinical signs of trachoma. MDA was given, and six months later an additional blood spot was taken from these same children. Ocular swabs were analyzed for C. trachomatis DNA and antibody responses for IgA and total IgG were measured in dried bloods spots.

Results: Baseline antibody responses showed an increase in antibody levels with age. By age 6, the percentage positive for IgG (96.0%) was much higher than for IgA (74.2%). Antibody responses to trachoma antigens declined significantly six months after drug treatment for most age groups. The percentage decrease in IgA response was much greater than for IgG. However, no instances of seroreversion were observed.

Conclusions: Data presented here suggest that focusing on concordant antibody responses in children will provide the best serological surveillance strategy for evaluation of trachoma control programs.

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Related in: MedlinePlus

Age prevalence curve of IgG and IgA responses at baseline. DBS were collected from participants and analyzed for IgG and IgA levels by Luminex multiplex assay. Seroprevalence (% antibody positive/total) was plotted against age. Blue closed circles show% positive to both pgp3 and CT694 antigens; green open circles show% positive to pgp3 but not CT694; purple open circles show% positive to CT694 but not pgp3; and red closed circles show% positive to any antigen.
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Figure 2: Age prevalence curve of IgG and IgA responses at baseline. DBS were collected from participants and analyzed for IgG and IgA levels by Luminex multiplex assay. Seroprevalence (% antibody positive/total) was plotted against age. Blue closed circles show% positive to both pgp3 and CT694 antigens; green open circles show% positive to pgp3 but not CT694; purple open circles show% positive to CT694 but not pgp3; and red closed circles show% positive to any antigen.

Mentions: Of DBS collected from 264 total participants, 208 samples were tested for IgG antibodies at baseline. The remainder were excluded if samples were collected at only a single time point from a given individual or if that individual was <1 year of age, since antibody responses in this age range may reflect transfer of maternal IgG. From the subset of 208 samples, clinical prevalence of TF/TI was 47%, infection prevalence by PCR was 25%, and IgG seroprevalence was 64%. In accordance with previous studies, serology showed high sensitivity, as 49/51 (96%) of PCR-positive individuals tested positive for IgG antibodies against pgp3 and CT694 (Figure 1). By age 4, IgG seroprevalence was 81% and by age 6, 97% of participants had IgG responses against CT694 or pgp3 (Figure 2). The concordance between pgp3 and CT694 IgG responses was 95.4%(OR = 696.83; 95% CI = 149.02-6691 [12]).


Longitudinal analysis of antibody responses to trachoma antigens before and after mass drug administration.

Goodhew EB, Morgan SM, Switzer AJ, Munoz B, Dize L, Gaydos C, Mkocha H, West SK, Wiegand RE, Lammie PJ, Martin DL - BMC Infect. Dis. (2014)

Age prevalence curve of IgG and IgA responses at baseline. DBS were collected from participants and analyzed for IgG and IgA levels by Luminex multiplex assay. Seroprevalence (% antibody positive/total) was plotted against age. Blue closed circles show% positive to both pgp3 and CT694 antigens; green open circles show% positive to pgp3 but not CT694; purple open circles show% positive to CT694 but not pgp3; and red closed circles show% positive to any antigen.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4016634&req=5

Figure 2: Age prevalence curve of IgG and IgA responses at baseline. DBS were collected from participants and analyzed for IgG and IgA levels by Luminex multiplex assay. Seroprevalence (% antibody positive/total) was plotted against age. Blue closed circles show% positive to both pgp3 and CT694 antigens; green open circles show% positive to pgp3 but not CT694; purple open circles show% positive to CT694 but not pgp3; and red closed circles show% positive to any antigen.
Mentions: Of DBS collected from 264 total participants, 208 samples were tested for IgG antibodies at baseline. The remainder were excluded if samples were collected at only a single time point from a given individual or if that individual was <1 year of age, since antibody responses in this age range may reflect transfer of maternal IgG. From the subset of 208 samples, clinical prevalence of TF/TI was 47%, infection prevalence by PCR was 25%, and IgG seroprevalence was 64%. In accordance with previous studies, serology showed high sensitivity, as 49/51 (96%) of PCR-positive individuals tested positive for IgG antibodies against pgp3 and CT694 (Figure 1). By age 4, IgG seroprevalence was 81% and by age 6, 97% of participants had IgG responses against CT694 or pgp3 (Figure 2). The concordance between pgp3 and CT694 IgG responses was 95.4%(OR = 696.83; 95% CI = 149.02-6691 [12]).

Bottom Line: By age 6, the percentage positive for IgG (96.0%) was much higher than for IgA (74.2%).The percentage decrease in IgA response was much greater than for IgG.However, no instances of seroreversion were observed.

View Article: PubMed Central - HTML - PubMed

Affiliation: Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, USA. hzx3@cdc.gov.

ABSTRACT

Background: Blinding trachoma, caused by the bacteria Chlamydia trachomatis, is a neglected tropical disease targeted for elimination by 2020. A major component of the elimination strategy is mass drug administration (MDA) with azithromycin. Currently, program decisions are made based on clinical signs of ocular infection, but we have been investigating the use of antibody responses for post-MDA surveillance. In a previous study, IgG responses were detected in children lacking clinical evidence of trachoma, suggesting that IgG responses represented historical infection. To explore the utility of serology for program evaluation, we compared IgG and IgA responses to trachoma antigens and examined changes in IgG and IgA post-drug treatment.

Methods: Dried blood spots and ocular swabs were collected with parental consent from 264 1-6 year olds in a single village of Kongwa District, central Tanzania. Each child also received an ocular exam for detection of clinical signs of trachoma. MDA was given, and six months later an additional blood spot was taken from these same children. Ocular swabs were analyzed for C. trachomatis DNA and antibody responses for IgA and total IgG were measured in dried bloods spots.

Results: Baseline antibody responses showed an increase in antibody levels with age. By age 6, the percentage positive for IgG (96.0%) was much higher than for IgA (74.2%). Antibody responses to trachoma antigens declined significantly six months after drug treatment for most age groups. The percentage decrease in IgA response was much greater than for IgG. However, no instances of seroreversion were observed.

Conclusions: Data presented here suggest that focusing on concordant antibody responses in children will provide the best serological surveillance strategy for evaluation of trachoma control programs.

Show MeSH
Related in: MedlinePlus