Burkholderia pseudomallei antibodies in individuals living in endemic regions in Northeastern Brazil

Abstract

A seroepidemiological investigation was conducted among the population of two municipalities in Northeastern Brazil. Immunoglobulin M (IgM) and IgG antibodies to Burkholderia pseudomallei were positive in 51.27% (161 in 317 samples) and 58.49% (186), respectively. IgM titers were higher in children than in adults. On the contrary, IgG increased progressively with age. We observed a significant association between agricultural occupation and raised IgM titers (P < 0.005) and IgG titers (P < 0.001), and between construction workers and raised IgG titers (P = 0.005). Antibody IgG avidities did not correlate with age. The highest titers of antibodies (1/800) showed the highest antibody avidity indexes (P < 0.01). Most of the serum samples recognized 45-kDa and 200-kDa bands by IgG1 and IgG2 subclasses. Our study showed a high seropositivity among individuals living in endemic regions of the state of Ceará, and highlights the need for further surveillance close to water courses such as dams and rivers in Northeastern Brazil.

Figure 1.

Percentage of positive (IgG) and IgM against a crude extract of Burkholderia pseudomallei IgG and IgM in serum samples from individuals residing in Tejuçuoca and Banabuiu, Ceará state, Brazil, according to the age range.

Figure 2.

Antibody IgG avidity indexes against a crude extract of Burkholderia pseudomallei in serum samples from individuals residing in Tejuçuoca and Banabuiu, Ceará state, Brazil, according to the age range. The results were expressed by the molar concentrations of potassium sodium thiocyanate (KSCN) necessary for elution of 50% of the bound immune complexes. The traces represent the avidity index mean for each group.

Figure 3.

Antibody IgG avidity indexes against a crude extract of Burkholderia pseudomallei in serum samples from individuals residing in Tejuçuoca and Banabuiu, Ceará state, Brazil, according to the titers of the IgG antibodies. The results were expressed by the molar concentrations of potassium sodium thiocyanate (KSCN) necessary for elution of 50% of the bound immune complexes. The traces represent the avidity index mean for each group.

Figure 4.

Detection of IgG1 and IgG2 subclasses against Burkholderia pseudomallei culture filtrate antigens by the Western blot technique employing serum samples from five individuals living in Banabuiu and Tejuçuoca. Lane 1 represents a high-tittered sample in enzyme-linked immunosorbent assay.