Western blotting for H7 VMN positive sera and H7 seronegative sera against concentrated H7N7 virus.

<p>All H7 positive sera were positive by western blot and immunogenic peptides were visualized at 67, 56–50, and 45 kDa corresponding to viral HA, NP/NA and HA1 respectively. The molecular weights of such peptides were estimated by including a low molecular weight protein marker (M) in the same run. VMN seronegative samples were also negative by western blotting. 1–4 show examples of positive human sera, 5–6 show negative human sera. Positive and negative H7N7 rat seraresults are shown on the left.</p

Demographic and serological profile of H7 sero-positivie subjects.

<p>Antibody titers against H7 were tested using virus neutralization assay while antibodies against H1 and H3 were measured using hemagglutination inhibition assay.</p

Immunofluorescence (IF) assay for H7 VMN positive sera and H7 seronegative sera.

<p>MDCK cells were inoculated with H7N7 virus then fixed and blocked by BSA. All sera that tested positive by VMN and 2 seronegative sera were diluted in blocking solution. FITC–conjugated goat anti–human IgG was then added. Fluorescently labeled cells were examined by fluorescence microscopy. Positive and negative control rat sera were tested and immunedetection was preformed using FITC–conjugated goat anti–rat IgG. An example of negative human sera (VMN titer <80) (A and B), negative rat sera (C), positive rat antisera (D), and positive human sera (VMN titer = 80) (E-L).</p

Characteristics of A/H7sero-positive participants at study time points.

<p>Characteristics of A/H7sero-positive participants at study time points.</p

Prevalence of anti-H7 antibodies among the study groups at different time points.

<p>Prevalence of anti-H7 antibodies among the study groups at different time points.</p