Department of Microbiology and Immunology, Faculty of Pharmacy, Alexandria University, Alexandria, 21521, Egypt.
Department of Biotechnology, Institute of Graduate Studies and Research (IGSR), Alexandria University, Alexandria, 21526, Egypt.
Int J Med Microbiol. 2020 Apr;310(3):151415. doi: 10.1016/j.ijmm.2020.151415. Epub 2020 Feb 29.
Pseudomonas aeruginosa is an evolving pathogen which can cause serious infections especially to immunocompromised patients. Its high resistance profile to antibiotics results in difficulty, and sometimes impossibility, in treating afflicted patients. Developing an effective vaccine against P. aeruginosa is an important approach to tackle this problem. A similar problematic situation exists for Acinetobacter baumannii. Several vaccine candidates have been investigated up till now but still there is no approved vaccine in the market. One important antigen of P. aeruginosa is the outer membrane protein F (OprF) which functions as a porin with relevant important roles in virulence. Previous studies focused mainly on the C-terminal peptidoglycan binding domain of OprF as a vaccine candidate. In the current study, we have investigated the N-terminal porin domain of OprF as a potential vaccine candidate against P. aeruginosa. Histidine-tagged recombinant N-terminal OprF (amino acid range 25-200; OprF) was overexpressed in Escherichia coli and purified using metal affinity chromatography. Swiss albino mice were immunized with OprF adjuvanted with Bacillus Calmette-Guérin (BCG) and alum and the immune response was evaluated. Immunized mice developed antigen-specific IgG1 and IgG2a and were protected against challenge by both P. aeruginosa and a clinical isolate of A. baumannii expressing OprF. Serum from OprF-immunized mice showed cross-reactivity with both pathogens using western blotting and whole cell enzyme-linked immunosorbent assay (ELISA). To our knowledge, this is the first report to demonstrate that the N-terminal domain of OprF is sufficiently immunogenic to protect against the two pathogens.
铜绿假单胞菌是一种不断进化的病原体，可导致免疫功能低下的患者发生严重感染。其对抗生素的高度耐药性导致治疗感染患者变得困难，有时甚至无法进行。开发针对铜绿假单胞菌的有效疫苗是解决这一问题的重要方法。鲍曼不动杆菌也存在类似的问题。到目前为止，已经研究了几种疫苗候选物，但市场上仍没有批准的疫苗。铜绿假单胞菌的一个重要抗原是外膜蛋白 F（OprF），它作为一种孔蛋白，在毒力方面发挥着重要作用。以前的研究主要集中在 OprF 的 C 末端肽聚糖结合结构域作为疫苗候选物。在本研究中，我们研究了 OprF 的 N 末端孔蛋白结构域作为针对铜绿假单胞菌的潜在疫苗候选物。用组氨酸标签表达并在大肠杆菌中过表达重组 N 末端 OprF（氨基酸范围 25-200；OprF），并用金属亲和层析法纯化。用卡介苗（BCG）和明矾佐剂免疫瑞士白化小鼠，并评估免疫反应。免疫小鼠产生了针对 OprF 的特异性 IgG1 和 IgG2a，并且对铜绿假单胞菌和表达 OprF 的临床分离株鲍曼不动杆菌的攻击都具有保护作用。使用 Western blot 和全细胞酶联免疫吸附试验（ELISA），来自 OprF 免疫小鼠的血清与两种病原体均发生交叉反应。据我们所知，这是首次报道证明 OprF 的 N 末端结构域具有足够的免疫原性，可预防两种病原体。
