Serological Response of Patients with Influenza A (H1N1) pdm09-Associated Pneumonia: An Observational Study

<div><p>Background</p><p>Little is known about the dynamics or magnitude of antibody response in patients with influenza A (H1N1) pdm09-associated pneumonia. We described and compared the antibody response to influenza A (H1N1) pdm09 in patients with and without pneumonia.</p> <p>Methods</p><p>We collected serum samples and determined antibody titers by the hemagglutination inhibition (HI) and microneutralization (mNT) assays from patients with RT-PCR confirmed influenza A (H1N1) pdm09 virus at baseline, 1, 2 and 6 months after onset of illness. </p> <p>Results</p><p>Fifty-nine patients were enrolled, 45 (76.3%) were between 15 and 60 years of age, 49 (83.1%) were hospitalized and 25 (42.4%) had complications with pneumonia. Ninety-four percent of patients had HI titers ≥ 1: 40 and 90% had mNT titers ≥ 1: 160 at 2 months after illness. Geometric mean titers (GMT) of HI and mNT increased significantly (<i>p</i><0.001) between baseline and months 1 or 2, then declined significantly (<i>p</i><0.001) at month 6 by the HI assay, but dropped to an insignificant level (<i>p</i>=0.24) by the mNT assay. The mNT-GMT was at least twice as high as corresponding HI antibodies over a 6 month period. The GMT of HI and mNT in those with pneumonia (1 mo) peaked earlier than that of those without pneumonia (2 mo). When adjusted by age and gender, those with pneumonia had a higher HI-GMT than those without pneumonia at 1 month (264 vs. 117, <i>p</i>=0.007), 2 months (212 vs. 159, <i>p</i>=0.013), and 6 months (160 vs. 82, <i>p</i>=0.018). </p> <p>Conclusions</p><p>The patients recovered from influenza A (H1N1) pdm09-associated pneumonia, clearly developed an earlier and more robust antibody response until 6 months after onset of illness. The results in our study are useful to determine an appropriate donor and timing to obtain convalescent plasma for adjunctive treatment of seriously ill patients with pandemic H1N1 influenza.</p> </div

Mean and standard deviation (SD) of bone mineral content of lumbar spine (BMCLS), bone area of lumbar spine (BALS), bone mineral content of total body (BMCTB), bone area of total body (BATB) and lean body mass values (LBM) in Thai children and adolescents (174 boys and 193 girls) for each age group.

<p>Mean and standard deviation (SD) of bone mineral content of lumbar spine (BMCLS), bone area of lumbar spine (BALS), bone mineral content of total body (BMCTB), bone area of total body (BATB) and lean body mass values (LBM) in Thai children and adolescents (174 boys and 193 girls) for each age group.</p

Anthropometric parameters (Height, Height Z-score, Weight, Weight Z-score and BMI) of Thai children and adolescents (174 boys and 193 girls) for each age group presented as mean±standard deviation (SD).

<p>Anthropometric parameters (Height, Height Z-score, Weight, Weight Z-score and BMI) of Thai children and adolescents (174 boys and 193 girls) for each age group presented as mean±standard deviation (SD).</p

BMD of the lumbar spine (BMDLS; grams per cm²) and total body (BMDTB; gram per cm²) at different Tanner stages among boys and girls.

<p>^*P<0.05, **P<0.01, ***P<0.001 compared with previous Tanner stage.</p

Geometric mean titers (GMT) of antibodies among different age groups.

<p>A) GMT of hemagglutination inhibition antibodies (HI-GMT) and B) GMT of neutralization antibodies (NT-GMT) among three age groups (Age < 15, 15-59 and ≥ 60) of 59 patients infected with influenza A (H1N1) pdm09 virus.</p

Geometric mean titers of hemagglutination inhibition (HI) and neutralization (NT) antibodies over 6 months.

<p>Geometric mean titers of hemagglutination inhibition (HI) and neutralization (NT) antibodies over 6 months.</p

Comparison between our current Thai vs. Indian and Chinese BMD normative data in children and adolescents among boys and girls.

<p>These figures were drawn based on data of the mean ± 2SD available from references <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0097218#pone.0097218-Xu1" target="_blank">[15]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0097218#pone.0097218-Khadilkar1" target="_blank">[17]</a>. The lines show mean ± 2SD. Thai BMDLS values are higher than those of Indian children and adolescent for both genders. Comparing to Chinese children, Thai children have higher BMDTB values for both genders.</p

Relationships between age vs. BMD of the lumbar spine (BMDLS; grams per cm²), BMAD of the lumbar spine (BMADLS; grams per cm³) and BMD of the total body (BMDTB; gram per cm²) among boys and girls.

<p>The lines show the best- fitted function with the factors age, age² and age³ (cubic function) for girls and age and age² (quadratic function) for boys.</p

CONSORT diagram shows the flow of the study participants through 6 months period.

<p>The patients who had at least one follow-up visit remained including in the study. </p

Relationships between age vs. BMC of the lumbar spine (BMCLS; grams), BMC of the total body (BMCTB; grams), BA of the lumbar spine (BALS; cm²), BA of the total body (BATB; cm²) and lean body mass (LBM; grams) among boys and girls.

<p>The lines show the best- fitted function with the factors age, age² and age³ (cubic function) for girls and age and age² (quadratic function) for boys.</p