Polysaccharide of Pneumocystis carinii cyst wall as a new target for therapy

肺孢子虫肺炎是免疫功能低下患者，特别是艾滋病患者中最常见和最严重的机会性感染。批准的治疗仅限于喷他脒和叶酸合成抑制剂，但这些药物在艾滋病患者中显示出很高的不良反应率，强调迫切需要额外的有效治疗<4-7>。然而，由于缺乏对这种寄生虫细胞特征的了解，进展受到了阻碍。该研究表明，用β-1，3-葡聚糖昆布五糖水解酶体外处理卡氏肺孢子虫包囊导致包囊壁溶解和苯胺蓝染色的损失，苯胺蓝染色是一种选择性地显示β-1，3-葡聚糖的染料。此外，在类固醇治疗的大鼠中，给予β-1，3-葡聚糖生物合成抑制剂--刺桐素A，可影响囊肿壁形成，抑制囊肿成熟，并预防严重肺炎。因此，这项研究不仅证明β-1，3-葡聚糖（酵母葡聚糖）是一种主要的囊壁成分，是寄生虫在大鼠体内生长所不可或缺的，而且还提出了一种治疗人类肺孢子虫病的新策略。

Pneumocystis pneumonia is the most common and most serious opportunistic infection in immunocompromised patients, particularly those with AIDS.Approved therapy is limited to pentamidine and inhibitors of folic acid synthesis, but these drugs show a high rate of adverse reactions in AIDS patients emphasizing the urgent need for additional effective therapies^<4-7>. Progress has, hawever, been hindered by lack of knowledge about this parasite's cellular characteristics. This study shows that in vitro treatment of P.carinii cysts with beta-1, 3-glucan laminaripentaohydrolase results in cyst wall lysis and loss of Aniline blue staining, a dye which selectively demonstrates 3-1, 3-glucan. Additionally, administration of aculeacin A, an inhibitor of beta-1, 3-glucan biosynthesis, affects cyst wall formation, inhibits cyst maturation, and prevents severe pneumonia in steroid-treated rats. Thus this study not only demonstrates that beta-1, 3-glucan (yeast glucan) is a major cyst wall component and indispensable for growth of the parasite in rats, but suggests a new therapeutic strategy for human pneumocystosis.