LACK OF REACTIVITY OF PARACOCCIDIOIDOMYCOSIS SERA IN THE DOUBLE IMMUNODIFFUSION TEST WITH THE GP43 ANTIGEN - REPORT OF 2 CASES

Sera from two patients with chronic active paracoccidioidomycosis yiel ded negative double immunodiffusion results with a culture filtrate an tigen from Paracoccidioides brasiliensis routinely used in our laborat ory. Complement fixation tests were positive for both sera using a pol ysaccharide-rich antigen. This study reports the results of a more ext ensive serological investigation of these two sera. Both a somatic ant igen and a saline extract from the fungus yielded positive results in the double immunodiffusion. However, the immunodominant 43 kDa glycopr otein antigen showed negative results, although it was recognized by b oth sera in the Western blot assay. The value of the double immunodiff usion as a single serological test in paracoccidioidomycosis diagnosis is discussed.