RESUMO
<p><b>BACKGROUND</b>To understand the optimal condition of single radial hemolysis (SRH) for diagnosis of avian influenza A (H5N1) virus in order that SRH could be performed in general laboratories.</p><p><b>METHODS</b>The effect of different concentration of virus and species of red blood cells, as well as kind and concentration of agarose on testing sensitivity of SRH was determined. Meanwhile the sensitivity and specificity of this method were compared with those of micro-neutralization test.</p><p><b>RESULTS</b>The optimal condition of SRH included the viral concentration of 1000 HA units per 0.1 ml packed chicken red blood cells, the agarose concentration of 1.0%, the compliment added into agarose-virus-rbc slides after diffusion of sera. The sensitivity and specificity of SRH were very similar to those of micro-neutralization test. Meanwhile, no cross reaction between antibodies, especially antibodies against N1 antigens, H5N1 and H1N1 viruses was detected.</p><p><b>CONCLUSION</b>The sensitivity and specificity of SRH were very similar to those of micro-neutralization assay. SRH could be performed in normal laboratories and be used for testing large scale serum samples.</p>