Wei Junfei, Damania Ashish, Gao Xin, Liu Zhuyun, Mejia Rojelio, Mitreva Makedonka, Strych Ulrich, Bottazzi Maria Elena, Hotez Peter J, Zhan Bin
Sabin Vaccine Institute and Texas Children's Hospital Center for Vaccine Development, National School of Tropical Medicine, Baylor College of Medicine, Houston, TX, 77030, USA.
McDonnell Genome Institute, Washington University School of Medicine, St. Louis, MO, 63108, USA.
Parasit Vectors. 2016 Sep 27;9(1):518. doi: 10.1186/s13071-016-1795-8.
The intestine of hookworms contains enzymes and proteins involved in the blood-feeding process of the parasite and is therefore a promising source of possible vaccine antigens. One such antigen, the hemoglobin-digesting intestinal aspartic protease known as Na-APR-1 from the human hookworm Necator americanus, is currently a lead candidate antigen in clinical trials, as is Na-GST-1 a heme-detoxifying glutathione S-transferase.
In order to discover additional hookworm vaccine antigens, messenger RNA was obtained from the intestine of male hookworms, Ancylostoma ceylanicum, maintained in hamsters. RNA-seq was performed using Illumina high-throughput sequencing technology. The genes expressed in the hookworm intestine were compared with those expressed in the whole worm and those genes overexpressed in the parasite intestine transcriptome were further analyzed.
Among the lead transcripts identified were genes encoding for proteolytic enzymes including an A. ceylanicum APR-1, but the most common proteases were cysteine-, serine-, and metallo-proteases. Also in abundance were specific transporters of key breakdown metabolites, including amino acids, glucose, lipids, ions and water; detoxifying and heme-binding glutathione S-transferases; a family of cysteine-rich/antigen 5/pathogenesis-related 1 proteins (CAP) previously found in high abundance in parasitic nematodes; C-type lectins; and heat shock proteins. These candidates will be ranked for downstream antigen target selection based on key criteria including abundance, uniqueness in the parasite versus the vertebrate host, as well as solubility and yield of expression.
The intestinal transcriptome of A. ceylanicum provides useful information for the identification of proteins involved in the blood-feeding process, representing a first step towards a reverse vaccinology approach to a human hookworm vaccine.
钩虫的肠道含有参与寄生虫吸血过程的酶和蛋白质，因此是潜在疫苗抗原的一个有前景的来源。一种这样的抗原，即来自人钩虫美洲板口线虫的血红蛋白消化性肠道天冬氨酸蛋白酶Na-APR-1，目前是临床试验中的主要候选抗原，同样，Na-GST-1（一种血红素解毒谷胱甘肽S-转移酶）也是。
为了发现更多的钩虫疫苗抗原，从感染仓鼠的锡兰钩虫雄虫肠道中获取信使核糖核酸。使用Illumina高通量测序技术进行RNA测序。将钩虫肠道中表达的基因与整个虫体中表达的基因进行比较，并对在寄生虫肠道转录组中过表达的那些基因进行进一步分析。
在鉴定出的主要转录本中，有编码蛋白水解酶的基因，包括一种锡兰钩虫APR-1，但最常见的蛋白酶是半胱氨酸蛋白酶、丝氨酸蛋白酶和金属蛋白酶。同样大量存在的还有关键分解代谢产物的特定转运蛋白，包括氨基酸、葡萄糖、脂质、离子和水；解毒和血红素结合谷胱甘肽S-转移酶；先前在寄生线虫中大量发现的富含半胱氨酸/抗原5/病程相关蛋白1家族（CAP）；C型凝集素；以及热休克蛋白。这些候选物将根据丰度、在寄生虫与脊椎动物宿主中的独特性以及表达的溶解度和产量等关键标准进行排序，以用于下游抗原靶点选择。
锡兰钩虫的肠道转录组为鉴定参与吸血过程的蛋白质提供了有用信息，代表了朝着人类钩虫疫苗的反向疫苗学方法迈出的第一步。
