An insight into the body louse, Pediculus humanus (Frisco strain), salivary gland contents.

Human body lice, Pediculus humanushumanus, are blood-feeding parasites that live in human clothing and feed several times per day.Saliva from louse bites induces local inflammation in the skin, pruiritis,and, if untreated, chronic Pediculosis has systemic negative health effects.Despite the well-established medical importance of body lice and their longstanding coevolution with humans, characterization of their saliva has been very limited.To address this, we extracted RNA and protein from two of the body louse’s morphologically distinct, sets of salivary glands (Bean-shaped and U-shaped) and generated transcript and protein profiles for each.Additionally, we performed fluorescent staining and confocal microscopy on each gland type to enhance descriptions of their morphology and detail their gross cellular architecture and arrangement.Analysis of the body louse salivary gene products and proteins revealed that the overwhelming majority were not closely related to biomolecules of known function; highlighting the organism’s unique and understudied saliva composition.Unexpectedly, and despite the contrasting morphology of the 2 gland types, there was ahigh degree of overlap in the salivary products produced.This finding suggests a strongDarwinian selection pressure to maintain both salivary glands types, given that it would seemingly be simpler to have a single morphologically homogeneous set of salivary glands.Here, we present the first next-generation sequencing and proteomic characterization of the human body louse sialome, discuss the potential physiological importance of louse salivary proteins, and present possible explanations for why lice have such a complex salivary gland organization despite ahigh degree of redundancy in protein repertoires between Bean and U-shaped salivary glands.

人体虱（Pediculus humanus humanus）是一类吸血性寄生虫，寄生于人体衣物之上，每日可多次吸血。虱叮咬时分泌的唾液会引发皮肤局部炎症与瘙痒，若未及时治疗，慢性虱病可引发全身性健康损害。尽管人体虱的医学重要性已得到广泛证实，且其与人类有着漫长的协同演化历程，但目前针对其唾液的研究仍极为有限。
为填补这一研究空白，我们从人体虱的两种形态学特征显著不同的唾液腺——豆形腺与U形腺——中提取了RNA与蛋白质，并分别构建了转录组与蛋白质组谱。此外，我们对两种腺体分别开展荧光染色与共聚焦显微镜成像，以完善其形态学描述，并详细阐明其整体细胞结构与排布方式。
对人体虱唾液基因产物与蛋白质的分析显示，绝大多数产物与已知功能的生物分子亲缘关系较远，凸显出该物种唾液组成的独特性与研究空白。令人意外的是，尽管两种腺体的形态差异显著，但其分泌的唾液产物却存在高度重叠。这一发现表明，维持两种唾液腺形态存在极强的达尔文选择压力——因为仅保留单一均一形态的唾液腺在演化路径上似乎更为简洁。
本研究首次完成了人体虱唾液组（sialome）的下一代测序与蛋白质组学表征，探讨了虱类唾液蛋白的潜在生理功能，并针对豆形与U形唾液腺间蛋白质组存在高度冗余的情况下，虱类为何演化出如此复杂的唾液腺组织结构这一问题，给出了可能的解释。