Recombinant proteins can be produced economically and in large quantities in culture, but crude antigens must be extracted from treponemes grown within the rabbit animal model. human and rabbit infections and a promising marker for the screening of syphilis. D159687 INTRODUCTION Syphilis is usually a chronic multistage disease caused by the spirochete subsp. and usually transmitted by sexual contact or congenitally (1). Syphilis has been a public health problem in the past 2 decades, with an estimated 12 million new cases occurring per year worldwide (2). Furthermore, syphilis has been considered one of factors that facilitates HIV contamination and transmission, and congenital syphilis causes more than half a million stillbirths or neonatal deaths annually (3). In China, syphilis has become one of the top five most reported infectious diseases and the most frequently reported sexually transmitted disease (STD), the incidence of which increased from 7.12 cases per 100,000 people in 2004 to 22 cases per 100,000 people in 2008 (4, 5). While the direct visualization of can be performed by dark-field microscopy (DFM), direct detection of is difficult due to the fact that cannot be cultured (MHA-TP), and the particle agglutination (TPPA) assay. Serum samples are first tested using a nontreponemal test and positive samples are analyzed with a treponema-specific Rabbit Polyclonal to PITX1 test (7, 8). The RPR and VDRL assessments show median sensitivities of 86% and 78%, respectively, for primary syphilis and 73% and 71%, respectively, for late syphilis (9). Furthermore, these nontreponemal D159687 assessments may result in false-positive detection in many situations, such as in patients with advanced age, pregnancy, and other bacterial infection (10). Enzyme-linked immunosorbent assays (ELISAs) that use nonspecific lipoprotein, purified whole extracts from proteins have been tested, including TpN15 (Tp0171), TpN17 (Tp0435), TpN44.5 (TmpA, Tp0768), TpN47 (Tp0574), Tp0453, Tp92 (Tp0326), and Tp0965 (13C17). Although these recombinant antigens are sometimes used in combination in commercial assessments and exhibit high sensitivity, not all of these antigens can be used for the detection of the early stage of syphilis. It is imperative to evaluate more specific and sensitive recombinant antigens for the serodiagnosis of syphilis. In a previous study, the researchers used isoelectric focusing (IEF) and nonequilibrium pH gel electrophoresis (NEPHGE) forms D159687 of two-dimensional gel electrophoresis (2DGE) to analyze the whole lysates of purified subsp. (Nichols strain) and identified a set of antigens specifically reactive with infected human serum (18). The bacterioferritin protein TpF1 (Tp1038) is usually one of these antigens, which exhibited high antibody responses with D159687 primary and other different stages of syphilis, suggesting that TpF1 might be useful in early diagnostic studies. The aim of this study was to further investigate the diagnostic potential of the recombinant protein TpF1 by expressing it in and purifying it from as a His-tagged fusion protein. Subsequently, the sensitivity of recombinant protein TpF1 was screened by using sera collected from individuals with syphilis. Since other spirochetal diseases such as Lyme disease and leptospirosis were expected to have antigens most similar to those of infections. Thus, TpF1 is usually a promising candidate for automated commercial ELISAs for screening of syphilis. MATERIALS AND METHODS Bacterial strains, plasmids, and DNA. The Nichols strain was supplied by Weiming Gu (Skin Diseases and Sexual Transmitted Diseases Hospital, Shanghai, China). The clinical isolates nhgz-01 and nhgz-02 were obtained from Diqing Luo (The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China). The Nichols strain and clinical isolates were propagated by intratesticular inoculation of adult New Zealand White rabbits.