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1.6 BIOLOGICAL SCIENCES
Candida species (spp.) are a part of the normal human microbiota. Candida dubliniensis mostly colonizes the oral cavity and/or respiratory tract (Mahelová and Růžička 2017), especially in HIV-infected individuals (Coleman et al.1997; Sullivan et al.2004; Wahab et al.2014), while Candida albicans is a common inhabitant of the gastrointestinal tract, urogenital tract and oral cavity (Sardi et al.2013; Höfs, Mogavero and Hube 2016). Candidiasis is the most common global fungal infection (Sardi et al.2013). Candida albicans has been isolated in more than 50% of candidiasis; however, the number of non-albicans spp. able to cause serious candidiasis has increased in recent years (Yapar 2014; Pu et al.2015; Sandhu et al.2017). Although C. dubliniensis is phylogenetically very similar to C. albicans, it differs in some genes, especially those coding for virulence-associated proteins. Candida dubliniensis lacks more than 168 genes characteristic of its ‘yeast-cousin’ C. albicans (Jackson et al.2009), the majority of them encoding proteins related to the yeast-to-hyphae transition, tissue invasion or biofilm development (Moran et al.2004; Jackson et al.2009; Moran, Coleman and Sullivan 2012). Moreover, C. dubliniensis manifests a higher predisposition to develop resistance to fluconazole (Sullivan et al.1995; Moran, Coleman and Sullivan 2012; Jordan et al.2014). On the other hand, both C. albincans and C. dubliniensis are able to form a biofilm (Sullivan et al.2004; Borghi et al.2014). Adherence is the first and most crucial step in biofilm development, and various surface antigens participate in this process (Chaffin 2008; Gow and Hube 2012; Hebecker et al.2014). CR3-RP (complement receptor 3-related protein) is one of the cell surface antigens of Candida spp. with functional and structural similarity to the human complement receptor 3 (CR3) expressed on neutrophils, macrophages and monocytes. CR3-RP has been demonstrated to bind human complement fragment iC3b and to mediate leukocyte diapedesis (Heidenreich and Dierich 1985; Bujdáková et al.1997). Additionally, CR3-RP seems to be an important immunogenic mannoprotein participating in adhesion and biofilm development (Bujdáková et al.2008, 2010). A fragment of CR3-RP was sequenced (DINGGGATLPQ), and according to this sequence, CR3-RP was categorized into the DING protein family (named after DINGGG N termini) (Bujdáková et al.2008; Bernier 2013). Some other surface proteins contributing to biofilm development have been described, such as Eap protein, the Als protein family, the Hwp1 or MP65 proteins (Gomez et al.1996; Nailis et al.2010; Finkel and Mitchell 2011; Araújo, Henriques and Silva 2017). Additionally, antibodies generated after the immunization of animals with some of the above proteins seems to be promising in tools focused on fighting yeast infections (Fujibayashi et al.2009; Mishra, Ali and Shukla 2015; Torosantucci et al.2017). Recent studies showed that antibodies targeting Als3 (Coleman et al.2009), MP65 (De Bernardis et al.2007) or another 42.7 kDa unnamed surface antigen in the Candida cell wall (Mishra, Ali and Shukla 2015) decreased adhesion and biofilm formation.
Chupáčová, J., Borghi, E. & Morace, G. (2018). Anti-biofilm Activity of Antibody Directed Against Surface Antigen Complement Receptor 3-Related Protein-Comparison of Candida Albicans and Candida Dubliniensis. Pathogens and Disease, vol. 76, no. 1, doi:10.1093/femspd/ftx127