Alcalá Belen, Salcedo Celia, Arreaza Luisa, Abad Raquel, Enríquez Rocio, De La Fuente Laura, Uría Maria Jose, Vázquez Julio A
Reference Laboratory for Neisseria, National Center of Microbiology, Institute of Health Carlos III, Ctra. Majadahonda-Pozuelo Km2, 28220 Majadahonda, Madrid, Spain.
J Med Microbiol. 2004 Jun;53(Pt 6):515-518. doi: 10.1099/jmm.0.05517-0.
The PorA protein is a potential candidate as a vaccine component against meningococcal disease. However, this protein experiences antigenic variation and is subject to phase variations to evade immune selective pressure. In this study, the mechanisms responsible for altered expression of the PorA protein were analysed in 50 non-subtypable strains isolated from patients with meningococcal disease in Spain. The porA gene was amplified from 47 of the 50 strains. The majority of isolates were not recognized by the subtyping panel, as a result of non-synonymous base changes in the variable regions of the porA gene. Two of these strains revealed a premature stop codon before the variable region VR1 of PorA due to a single base-pair substitution at position 109 of the porA coding region. Another two presented a homopolymeric tract of eight adenine residues in the coding region, producing a DNA strand-slippage mechanism and PorA phase variation.
PorA蛋白是作为抗脑膜炎球菌病疫苗成分的潜在候选物。然而，这种蛋白会发生抗原变异，并会经历相变以逃避免疫选择压力。在本研究中，对从西班牙脑膜炎球菌病患者中分离出的50株不可分型菌株中负责PorA蛋白表达改变的机制进行了分析。从50株菌株中的47株扩增出了porA基因。由于porA基因可变区的非同义碱基变化，大多数分离株未被分型专家组识别。其中两株菌株由于porA编码区第109位的单碱基对替换，在PorA的可变区VR1之前出现了提前终止密码子。另外两株在编码区呈现出八个腺嘌呤残基的同聚物序列，产生了DNA链滑动机制和PorA相变。
