Distribution of immunoglobulin classes and IgG subclasses against a culture filtrate antigen of Burkholderia pseudomallei in melioidosis patients

The class and subclass distribution of antibody response to the culture fil trate antigen (CFA) of Burkholderia pseudomallei was examined in the sera o f 45 septicaemic and 17 localised melioidosis cases and 40 cases clinically suspected of melioidosis and the results were compared with those from hig h-risk and healthy control groups. The geometric mean titre index (GMTI) va lues for all classes and subclasses of immunoglobulins examined were higher for sera from the proven and clinically suspected melioidosis cases than f or the control groups. However, the highest response in the three patient g roups was that of IgG with GMTIs ranging from 219.4 to 291.6 and the lowest was for IgM with GMTIs of 22.5, 24.3 and 28.7. The IgA response was interm ediate with GMTIs ranging from 119.2 to 170. The GMTIs were highest for IgG in septicaemic and localised infections and for IgA and IgM in localised i nfections. As regards IgG subclass distribution, IgG1 and IgG2 were the pre dominant subclasses produced against the CFA in contrast to IgG3 and IgG4, which were produced in low amounts. None of the sera from the control group s had any significant titres of antibodies.