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

本研究采用RT-PCR方法，从鹌鹑法氏囊和哈氏腺中提取总RNA，获得抗菌肽fowlicidin（f）-1、-2和-3的前体基因。结果，f-1、f-2和f-3cDNA总是从BF获得。然而，迄今为止，在HG中仅检测到f-2 cDNA。原位杂交和免疫组织化学分析表明，f-2在BF的管腔上皮和淋巴滤泡中表达。合成的f-2通过破坏细菌细胞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生长抑制活性。脂多糖（LPS）结合实验表明，f-2具有结合细菌LPS的能力，这是革兰氏阴性菌的外膜的组成部分。内毒素中和活性的f-2也证实了鲎试剂变形细胞裂解物测定。

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.