Infection in a rat model reactivates attenuated virulence after long-term axenic culture of Acanthamoeba spp

Abstract

Prolonged culturing of many microorganisms leads to the loss of virulence and a reduction of their infective capacity. However, little is known about the changes in the pathogenic strains of Acanthamoeba after long culture periods. Our study evaluated the effect of prolonged culturing on the invasiveness of different isolates of Acanthamoeba in an in vivo rat model. ATCC strains of Acanthamoeba, isolates from the environment and clinical cases were evaluated. The in vivo model was effective in establishing the infection and differentiating the pathogenicity of the isolates and re-isolates. The amoebae cultured in the laboratory for long periods were less virulent than those that were recently isolated, confirming the importance of passing Acanthamoeba strains in animal models.

Neoparamoeba perurans loses virulence during clonal culture

“…Furthermore, loss of virulence in an Acanthamoeba sp. correlated with a reduced proteolytic profile of the attenuated amoebae (Verissimo et al, 2013). The in vitro CPE identified here and its relevance to AGD is unclear given that extensive histological studies on AGD-affected salmon revealed no evidence of cytolytic activity (Adams and Nowak, 2001).…”

Distinct immunomodulatory properties of extracellular vesicles released by different strains of Acanthamoeba

“…On the other hand, AR15 (genotype T11) is an environmental strain considered non‐pathogenic by some phenotypic parameters (Duarte et al, 2013). AP4 (genotype T2), in turn, is a freshwater isolate with milder pathogenic potential, since it exhibited features of low pathogenicity in a study (Da Rocha‐Azevedo & Costa e Silva‐Filho, 2007), but it could experimentally induce pulmonary disease in rats (Veríssimo et al, 2013). Considering these aspects, the higher proteases activities in ALX and R2P5 indicated that EVs may in part affect the pathogenicity expression of Acanthamoeba .…”

“… Note : Genotypic and physiological characterization described in (a) Duarte et al (2013), (b) Cirelli et al (2020), (c) Possamai et al (2018), and (d) Da Rocha‐Azevedo and Costa e Silva‐Filho (2007), (e) Verissimo et al (2013). …”

Comparative proteomic profiling of newly acquired, virulent and attenuated Neoparamoeba perurans proteins associated with amoebic gill disease

“…Attenuation of parasitic virulence has been attributed to long term cultivation in vitro that negatively impacts the organisms capacity to establish infection in the host model [35][36][37] . A complete loss of virulence has been previously reported during experimental in vivo trials using a clonal culture of N. perurans that was maintained in vitro for 3 years 19,38 .…”