Identification, localization and functional analysis of antimicrobial peptides in the quail Harderian gland and bursa of Fabricius.

利用RT-PCR技术，从鹌鹑法氏囊（BF）和哈德氏腺（HG）制备的总RNA样品中获得抗菌肽fowlicidin (f)-1、-2和-3前体的编码cdna。结果，f-1、-2和-3 cdna总是从BF中获得。然而，迄今为止，HG中仅检测到f-2 cDNA。原位杂交和免疫细胞组织化学分析显示，f-2在BF的管腔上皮和淋巴滤泡中表达。合成f-2通过破坏细菌膜，对革兰氏阴性菌大肠杆菌和革兰氏阳性菌金黄色葡萄球菌具有抑制生长的活性。脂多糖（LPS）结合实验表明，f-2具有结合细菌脂多糖的能力，脂多糖是革兰氏阴性菌外膜的组成部分。f-2的内毒素中和活性也通过鲎试剂测定得到证实。

We intended to obtain cDNAs encoding precursor for antimicrobial peptide fowlicidin (f)-1, -2, and -3 from total RNA samples prepared from the quail bursa of Fabricius (BF) and Harderian gland (HG) by RT-PCR. As a result, f-1, -2, and -3 cDNAs were invariably obtained from the BF. However, only f-2 cDNA was detected in HG, so far studied. In situ hybridization and immunocytohistochemical analyses revealed that f-2 is expressed in the epithelium of lumen and the lymphoid follicles in the BF. Synthetic f-2 exerted a growth-inhibiting activity toward the gram-negative bacterium Escherichia coli and gram-positive bacterium Staphylococcus aureus through the destructing the bacterial membrane. Lipopolysaccharide (LPS)-binding assay showed that f-2 possessed an ability to bind the bacterial LPS, which is a constituent of the outer membrane of the gram-negative bacteria. The endotoxin-neutralizing activity of f-2 was also confirmed by the Lymulus amebocyte lysate assay.