Division of Parasitology, CSIR-Central Drug Research Institute, BS 10/1, Sector 10 Jankipuram Extension, Sitapur Road, Lucknow, UP, 226031, India.
Academy of Scientific and Innovative Research, New Delhi, India.
Parasit Vectors. 2017 Jan 24;10(1):40. doi: 10.1186/s13071-016-1963-x.
In the past, immune responses to several Brugia malayi immunodominant antigens have been characterized in filaria-infected populations; however, little is known regarding Wolbachia proteins. We earlier cloned and characterized few B. malayi (trehalose-6-phosphate phosphatase, Bm-TPP and heavy chain myosin, BmAF-Myo) and Wolbachia (translation initiation factor-1, Wol Tl IF-1 and NAD-dependent DNA ligase, wBm-LigA) proteins and investigated the immune responses, which they triggered in animal models. The current study emphasizes on immunological characteristics of these proteins in three major categories of filarial endemic zones: endemic normal (EN, asymptomatic, amicrofilaraemic; putatively immune), microfilariae carriers (MF, asymptomatic but microfilaraemic), and chronic filarial patients (CP, symptomatic and mostly amicrofilaraemic).
Immunoblotting and ELISA were carried out to measure IgG and isotype antibodies against these recombinant proteins in various clinical categories. Involvement of serum antibodies in infective larvae killing was assessed by antibody-dependent cellular adhesion and cytotoxicity assay. Cellular immune response was investigated by in vitro proliferation of peripheral blood mononuclear cells (PBMCs) and reactive oxygen species (ROS) generation in these cells after stimulation.
Immune responses of EN and CP displayed almost similar level of IgG to Wol Tl IF-1 while other three proteins had higher serum IgG in EN individuals only. Specific IgA, IgG1, IgG3 and IgM to Bm-TPP were high in EN subjects, while BmAF-Myo additionally showed elevated IgG2. Enhanced IgA and IgG3 were detected in both EN and CP individuals in response to Wol Tl IF-1 antigen, but IgG1 and IgM were high only in EN individuals. wBm-LigA and BmAF-Myo exhibited almost similar pattern of antibody responses. PBMC isolated from EN subjects exhibited higher proliferation and ROS generation when stimulated with all three proteins except for Wol Tl IF-1.
Overall, these findings display high immunogenicity of all four proteins in human subjects and revealed that the EN population was exposed to both B. malayi and Wolbachia proteins simultaneously. In addition, immune responses to Wol Tl IF-1 suggest possible role of this factor in Wolbachia-induced pathological responses while immune responses to other three proteins suggest that these can be explored further as vaccine candidates.
过去，人们已经对几种盘尾丝虫免疫优势抗原的免疫反应进行了描述，这些抗原存在于感染盘尾丝虫的人群中；然而，对于沃尔巴克氏体蛋白，人们知之甚少。我们之前已经克隆和鉴定了几种班氏丝虫（海藻糖-6-磷酸磷酸酶，Bm-TPP 和肌球蛋白重链，BmAF-Myo）和沃尔巴克氏体（翻译起始因子-1，Wol Tl IF-1 和 NAD 依赖性 DNA 连接酶，wBm-LigA）蛋白，并研究了它们在动物模型中引发的免疫反应。本研究强调了这些蛋白在三个主要的丝虫流行区类别中的免疫学特征：流行正常（EN，无症状，无微丝蚴血症；推测为免疫）、微丝蚴携带者（MF，无症状但有微丝蚴血症）和慢性丝虫病患者（CP，有症状且大多无微丝蚴血症）。
通过免疫印迹和 ELISA 法，在各种临床类别中测量针对这些重组蛋白的 IgG 和同种型抗体。通过抗体依赖性细胞黏附和细胞毒性测定评估血清抗体在杀伤感染性幼虫中的作用。通过刺激后外周血单核细胞（PBMCs）的体外增殖和这些细胞中活性氧（ROS）的产生来研究细胞免疫反应。
EN 和 CP 的免疫反应显示出对 Wol Tl IF-1 的 IgG 几乎相似的水平，而其他三种蛋白仅在 EN 个体中具有更高的血清 IgG。EN 个体中对 Bm-TPP 的特异性 IgA、IgG1、IgG3 和 IgM 较高，而 BmAF-Myo 另外还显示出 IgG2 的升高。EN 和 CP 个体对 Wol Tl IF-1 抗原的反应均显示出增强的 IgA 和 IgG3，但仅在 EN 个体中 IgE 和 IgM 较高。wBm-LigA 和 BmAF-Myo 表现出几乎相似的抗体反应模式。与 Wol Tl IF-1 不同，从 EN 个体中分离的 PBMC 在受到这三种蛋白刺激时表现出更高的增殖和 ROS 生成。
总体而言，这些发现显示了这四种蛋白在人体中的高度免疫原性，并表明 EN 人群同时接触了班氏丝虫和沃尔巴克氏体蛋白。此外，对 Wol Tl IF-1 的免疫反应表明该因子可能在沃尔巴克氏体诱导的病理反应中发挥作用，而对其他三种蛋白的免疫反应表明，这些蛋白可以进一步作为疫苗候选物进行探索。
