The biology of Acanthamoeba keratitis.

Acanthamoeba keratitis (AK) is a rare protozoal infection of the cornea. At least eight species of Acanthamoeba are known to cause this sight-threatening disease of the ocular surface. Acanthamoeba spp. exist in a wide array of niches ranging from thermal springs to under ice and every conceivable habitat in between. Contact lens wear is the leading risk factor for AK and is practiced by over 30 million individuals in the United States, yet the incidence of AK is less than 33 cases per one million contact lens wearers. Serological studies have reported that 90%-100% of individuals with no history of AK possess antibodies specific for Acanthamoeba antigens indicating that exposure to this organism is commonplace, yet disease is remarkably rare. Animal studies have shed light on the pathobiology and immunobiology of AK and indicate that a constellation of factors including the ocular surface microbiome and the microbiome of Acanthamoeba itself contribute to the pathogenesis of AK. Interesting, secretory antibodies produced by the adaptive immune response can prevent the initiation of corneal infection, but once Acanthamoeba trophozoites breach the corneal epithelium the adaptive immune system is helpless in altering the course of AK. It has been almost 50 years since AK was first described, yet many questions remain unanswered about this curious and enigmatic disease of the ocular surface.

Acanthamoeba spp. monoclonal antibody against a CPA2 transporter: a promising molecular tool for acanthamoebiasis diagnosis and encystment study.

Free-living amoeba of the genus Acanthamoeba are ubiquitous protozoa involved in opportunistic and non-opportunistic infection in humans, such as granulomatous amoebic encephalitis and amoebic keratitis. Both infections have challenging characteristics such as the formation of the resistant cysts in infected tissues, hampering the treatment and most usual diagnosis depending on time-consuming and/or low sensitivity techniques. The use of monoclonal antibodies presents itself as an opportunity for the development of more effective alternative diagnostic methods, as well as an important and useful tool in the search for new therapeutic targets. This study investigated the possibility of using a previously produced monoclonal antibody (mAb3), as a diagnostic tool for the detection of Acanthamoeba trophozoites by direct and indirect flow cytometry and immunofluorescence. Immunoprecipitation assay and mass spectrometry allowed the isolation of the antibody's target and suggested it is a transporter part of the CPA (cation: proton antiporter) superfamily. In vitro tests indicate an important role of this target in Acanthamoeba's encystment physiology. Our results support the importance of studying the role of CPA2 transporters in the context of acanthamoebiasis, as this may be a way to identify new therapeutic candidates.

Acanthamoeba proteases contribute to macrophage activation through PAR1 , but not PAR2.

AIM: Acanthamoeba infections are characterized by an intense localized innate immune response associated with an influx of macrophages. Acanthamoeba protease production is known to affect virulence. Herein, the ability of Acanthamoeba trophozoite proteases, of either the laboratory Neff strain or a recently isolated clinical strain, to stimulate IL-12 and IL-6 and to activate protease-activated receptors, PAR1 and PAR2 expressed on murine macrophages, was investigated. METHOD AND RESULTS: Using selected protease inhibitors, leupeptin and E64, we showed that Acanthamoeba proteases can stimulate IL-12 and IL-6 by murine macrophages. Subsequently, using specific antagonists to inhibit PAR1 , and bone marrow-derived macrophages from PAR2 gene-deficient mice, we demonstrate that PAR1 , but not PAR2 contributes to macrophage IL-12 production in response to Acanthamoeba. In contrast, Acanthamoeba-induced IL-6 production is PAR1 and PAR2 independent. CONCLUSION: This study shows for the first time the involvement of PARs, expressed on macrophages, in the response to Acanthamoeba trophozoites and might provide useful insight into Acanthamoeba infections and their future treatments.

Production of a monoclonal antibody against a mannose-binding protein of Acanthamoeba culbertsoni and its localization.

Amoebae from the genus Acanthamoeba are facultative pathogens of humans and other animals. In humans they most frequently infect the eye causing a sight threatening infection known as Acanthamoeba keratitis (AK), and also cause an often fatal encephalitis (GAE). A mannose-binding protein (MBP) has been identified as being important for Acanthamoeba infection especially in AK. This lectin has previously been characterized from Acanthamoeba castellanii as consisting of multiple 130 kDa subunits. MBP expression correlates with pathogenic potential and is expressed in a number of Acanthamoeba species. Here we report the purification of a similar lectin from Acanthamoeba culbertsoni and the production of a monoclonal antibody to it. The A. culbertsoni MBP was isolated by affinity chromatography using α-D-mannose agarose and has an apparent molecular weight of 83 kDa. The monoclonal antibody is an IgM that is useful in both western blots and immunofluorescence. We expect that this antibody will be useful in the study of the pathology of A. culbertsoni and in its identification in clinical samples.

Relationship between antioxidant defense in Acanthamoeba spp. infected lungs and host immunological status.

The role of oxidative stress in the pathogenicity of acanthamoebiasis is an important aspect of the intricate and complex host-parasite relationship. The aim of this experimental study was to determine oxidative stress through the assessment of lipid peroxidation product (LPO) levels and antioxidant defense mechanism in Acanthamoeba spp. lung infections in immunocompetent and immunosuppressed hosts. In Acanthamoeba spp. infected immunocompetent mice we noted a significant increase in lung lipid peroxidation products (LPO) at 8 days and 16 days post infection (dpi). There was a significant upregulation in lung LPO in immunocompetent and immunosuppressed mice infected by Acanthamoeba spp. at 16 dpi. The superoxide dismutase activity decreased significantly in lungs in immunosuppressed mice at 8 dpi. The catalase activity was significantly upregulated in lungs in immunocompetent vs. immunosuppressed group and in immunocompetent vs. control mice at 16 dpi. The glutathione reductase activity was significantly lower in immunosuppressed group vs. immunosuppressed control at 24 dpi. We found significant glutathione peroxidase downregulation in immunocompetent and immunosuppressed groups vs. controls at 8 dpi, and in immunosuppressed vs. immunosuppressed control at 16 dpi. The consequence of the inflammatory response in immunocompetent and immunosuppressed hosts in the course of experimental Acanthamoeba spp. infection was the reduction of the antioxidant capacity of the lungs resulting from changes in the activity of antioxidant enzymes. Therefore, the imbalance between oxidant and antioxidant processes may play a major role in pathology associated with Acanthamoeba pneumonia.

Detection of serum antibodies in children and adolescents against Balamuthia mandrillaris, Naegleria fowleri and Acanthamoeba T4.

The presence of free-living amoebae of the genera Naegleria, Acanthamoeba and Balamuthia, which contain pathogenic species for humans and animals, has been demonstrated several times and in different natural aquatic environments in the northwest of Mexico. With the aim of continuing the addition of knowledge about immunology of pathogenic free-living amoebae, 118 sera from children and adolescents, living in three villages, were studied. Humoral IgG response against B. mandrillaris, N. fowleri and Acanthamoeba sp. genotype T4, was analyzed in duplicate to titers 1: 100 and 1: 500 by enzyme-linked immunosorbent assay (ELISA). Children and adolescents ages ranged between 5 and 16 years old, with a mean of 9 years old, 55% males. All tested sera were positive for the 1: 100 dilution, and in the results obtained with the 1: 500 dilution, 116 of 118 (98.3%) were seropositive for N. fowleri, 101 of 118 (85.6%) were seropositive for Acanthamoeba sp. genotype T4, and 43 of 118 (36.4%) were seropositive for B. mandrillaris. The statistical analysis showed different distributions among the three communities and for the three species of pathogenic free-living amoebae, including age. Lysed and complete cells used as Balamuthia antigens gave differences in seropositivity.

IL-17A-mediated protection against Acanthamoeba keratitis.

Acanthamoeba keratitis (AK) is a very painful and vision-impairing infection of the cornea that is difficult to treat. Although past studies have indicated a critical role of neutrophils and macrophages in AK, the relative contribution of the proinflammatory cytokine, IL-17A, that is essential for migration, activation, and function of these cells into the cornea is poorly defined. Moreover, the role of the adaptive immune response, particularly the contribution of CD4(+) T cell subsets, Th17 and regulatory T cells , in AK is yet to be understood. In this report, using a mouse corneal intrastromal injection-induced AK model, we show that Acanthamoeba infection induces a strong CD4(+) T effector and regulatory T cell response in the cornea and local draining lymph nodes. We also demonstrate that corneal Acanthamoeba infection induces IL-17A expression and that IL-17A is critical for host protection against severe AK pathology. Accordingly, IL-17A neutralization in Acanthamoeba-infected wild-type mice or Acanthamoeba infection of mice lacking IL-17A resulted in a significantly increased corneal AK pathology, increased migration of inflammatory cells at the site of inflammation, and a significant increase in the effector CD4(+) T cell response in draining lymph nodes. Thus, in sharp contrast with other corneal infections such as herpes and Pseudomonas aeruginosa keratitis where IL-17A exacerbates corneal pathology and inflammation, the findings presented in this article suggest that IL-17A production after Acanthamoeba infection plays an important role in host protection against invading parasites.

Pathobiology and Immunobiology of Acanthamoeba Keratitis: Insights from Animal Models
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Acanthamoeba keratitis (AK) is a rare but sight-threatening disease caused by pathogenic species of Acanthamoeba. Despite its ubiquitous nature, the incidence of AK is relatively low compared to other forms of infectious keratitis. Although contact lens wear is a major risk factor, exposure to contaminated water and ocular trauma are also associated with AK. Once a patient develops AK the prognosis is very poor unless an aggressive treatment regimen is initiated early. Some of the intriguing features of AK are the lack of immunological memory, resistance of the dormant cyst form to treatment, differences between the pathogenic strains and soil isolates of Acanthamoeba and the unique role of the innate immune system in controlling this disease. Understanding the series of steps involved in the pathogenesis of the disease and the host immune response against Acanthamoeba antigens is crucial for developing effective therapeutic strategies targeting the disease.

Evaluation of allergic sensitivity to Acanthamoeba allergen in patients with chronic cough.

BACKGROUND: Acanthamoeba and their proteins can elicit severe allergic airway inflammation in experimental mice. OBJECTIVE: Although Acanthamoeba can induce severe allergic airway inflammation in mice, there is no allergenicity data for humans. METHODS: We performed a skin-prick test on 65 patients with chronic cough by using 54 previously known allergens and Acanthamoeba excretory-secretory proteins and enzyme-linked immunosorbent assay on 34 patients to evaluate Acanthamoeba-specific serum immunoglobulin (Ig) levels. To detect a novel Acanthamoeba allergen, Western blot analysis was performed on serum from patients who reacted positively to Acanthamoeba or some pollen allergens. RESULTS: After skin-prick testing, 29 patients (44.6%) showed positive reactions to one or more common aeroallergens. Acanthamoeba allergenicity was evaluated in 4 of 65 subjects (6.1%). An Acanthamoeba-positive reaction was closely related to several pollen allergens, especially willow tree, poplar, elm, oak, velvet grass, and cockroach. Average levels of Acanthamoeba-specific IgG subtypes in patient serum did not differ compared with healthy subjects; however, Acanthamoeba-specific IgE titers of patients were significantly higher than in healthy subjects. IgE antibodies of patients who tested positive in the skin-prick test reacted strongly to the 15 kDa excretory-secretory protein. Moreover, these antigens also reacted with those who tested positive in the skin-prick test to pollens. CONCLUSION: Taken together, our results indicated that some patients with allergy showed a positive response to the skin-prick test and that they also have high IgE serum levels. However, further experimental investigation is warranted because our preliminary findings indicated that Acanthamoeba might be a new allergen in humans.

Toll-like receptors in the brain of mice following infection with Acanthamoeba spp.

The Toll-like receptors (TLRs) of the innate immune system play an important role in the recognition of pathogens such as bacteria, viruses, fungi, and parasites. In this study, we examined the changes in the level of expression of TLR2 and TLR4 mRNA and protein in the brains of mice infected with Acanthamoeba spp. The Acanthamoeba strains were isolated from a patient with Acanthamoeba keratitis (AK) (Ac55) and Malta Lake (Ac43). In the brain isolated from mice at 2 days post-infection (dpi) with Acanthamoeba strains Ac55 and Ac43, mRNAs for TLR2 and TLR4 were significantly more strongly expressed in comparison with the uninfected mice. In Acanthamoeba-infected mice, TLR2 and TLR4 expression was detected in neurons, glial cells, and endothelial cells within the neocortex. These receptors showed more intense expression in ependymocytes of the choroid plexus of infected mice at 2 dpi. Increased levels of TLR2 and TLR4 mRNA expression in infected mice suggest the involvement of these TLRs in the recognition of Acanthamoeba spp. pathogen-associated molecular patterns (PAMPs).

Development of an immunochromatographic assay kit using fluorescent silica nanoparticles for rapid diagnosis of Acanthamoeba keratitis.

We developed an immunochromatographic assay kit that uses fluorescent silica nanoparticles bound to anti-Acanthamoeba antibodies (fluorescent immunochromatographic assay [FICGA]) and evaluated its efficacy for the detection of Acanthamoeba and diagnosis of Acanthamoeba keratitis (AK). The sensitivity of the FICGA kit was evaluated using samples of Acanthamoeba trophozoites and cysts diluted to various concentrations. A conventional immunochromatographic assay kit with latex labels (LICGA) was also evaluated to determine its sensitivity in detecting Acanthamoeba trophozoites. To check for cross-reactivity, the FICGA was performed by using samples of other common causative pathogens of infectious keratitis, such as Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermidis, and Candida albicans. Corneal scrapings from patients with suspected AK were tested with the FICGA kit to detect the presence of Acanthamoeba, and the results were compared with those of real-time PCR. The FICGA kit detected organisms at concentrations as low as 5 trophozoites or 40 cysts per sample. There were no cross-reactivities with other pathogens. The FICGA was approximately 20 times more sensitive than the LICGA for the detection of Acanthamoeba trophozoites. The FICGA kit yielded positive results for all 10 patients, which corresponded well with the real-time PCR results. The FICGA kit demonstrated high sensitivity for the detection of Acanthamoeba and may be useful for the diagnosis of AK.

Protein profiles and immunoreactivities of Acanthamoeba morphological groups and genotypes.

Acanthamoeba is a free-living protozoan found in a wide variety of habitats. A classification of Acanthamoeba into currently eighteen genotypes (T1-T18) has been established, however, data on differences between genotypes on the protein level are scarce. The aim of this study was to compare protein and immunoreactivity profiles of Acanthamoeba genotypes. Thirteen strains, both clinical and non-clinical, from genotypes T4, T5, T6, T7, T9, T11 and T12, representing three morphological groups, were investigated for their protein profiles and IgG, IgM and IgA immunoreactivities. It was shown that protein and immunoreactivity profiles of Acanthamoeba genotypes T4, T5, T6, T7, T9, T11 and T12 are clearly distinct from each other, but the banding patterns correlate to the morphological groups. Normal human sera revealed anti-Acanthamoeba antibodies against isolates of all investigated genotypes, interestingly, however only very weak IgM and virtually no IgA immunoreactivity with T7 and T9, both representing morphological group I. The strongest IgG, IgM and IgA immunoreactivities were observed for genotypes T4, T5 and T6. Differences of both, protein and immunological patterns, between cytopathic and non-cytopathic strains, particularly within genotype T4, were not at the level of banding patterns, but rather in expression levels.

Physiological, morphological, and immunochemical parameters used for the characterization of clinical and environmental isolates of Acanthamoeba.

The factors that characterize Acanthamoeba strains as harmless or potentially pathogenic have not been elucidated. Analysing the in vitro and in vivo parameters of Acanthamoeba samples, including heat tolerance at temperatures close to that of the human body, cytopathic effects, and their ability to cause infections in animals, has been proposed to identify their pathogenic potential. Another promising criterion for differentiating strains is the analysis of their biochemical and immunochemical properties. In this study, a comparative evaluation between clinical and environmental Acanthamoeba isolates was performed on the basis of physiological, morphological, and immunochemical criteria. Crude antigens were used to characterize the protein profiles by electrophoresis and immunize mice to produce polyclonal and monoclonal antibodies. The antibodies were characterized using ELISA, Western blotting, and immunofluorescence techniques. The results obtained with polyclonal antibodies suggest the presence of specific proteins for each studied isolate and co-reactive immunochemical profiles among conserved components. Ten monoclonal antibody clones were obtained; mAb3 recognized 3 out of 4 samples studied. The results of this study may help standardize criteria for identifying and characterizing Acanthamoeba strains. Taken together, our results support the view that a set of features may help differentiate Acanthamoeba species and isolates.

Detection of Acanthamoeba spp. using carboxylesterase antibody and its usage for diagnosing Acanthamoeba-keratitis.

Contact lens usage has contributed to increased incidence rates of Acanthamoeba keratitis (AK), a serious corneal infection that can lead to blindness. Since symptoms associated with AK closely resemble those incurred by bacterial or fungal keratitis, developing a diagnostic method enabling rapid detection with a high degree of Acanthamoeba-specificity would be beneficial. Here, we produced a polyclonal antibody targeting the carboxylesterase (CE) superfamily protein secreted by the pathogenic Acanthamoeba and evaluated its diagnostic potential. Western blot analysis revealed that the CE antibody specifically interacts with the cell lysates and conditioned media of pathogenic Acanthamoeba, which were not observed from the cell lysates and conditioned media of human corneal epithelial (HCE) cells, Fusarium solani, Staphylococcus aureus, and Pseudomonas aeruginosa. High titers of A. castellanii-specific antibody production were confirmed sera of immunized mice via ELISA, and these antibodies were capable of detecting A. castellanii from the cell lysates and their conditioned media. The specificity of the CE antibody was further confirmed on A. castellanii trophozoites and cysts co-cultured with HCE cells, F. solani, S. aureus, and P. aeruginosa using immunocytochemistry. Additionally, the CE antibody produced in this study successfully interacted with 7 different Acanthamoeba species. Our findings demonstrate that the polyclonal CE antibody specifically detects multiple species belong to the genus Acanthamoeba, thus highlighting its potential as AK diagnostic tool.

Toll-like receptor 4 signalling pathway activation in a rat model of Acanthamoeba Keratitis.

The pathogenesis of Acanthamoeba keratitis (AK) is complicated. In our previous studies, TLR4 was found involved in the process of infection by Acanthamoeba in human corneal cells. The purpose of this study was to investigate the role of Toll-like receptor 4 (TLR4) signalling pathway in Wistar rats challenged with Acanthamoeba. The rat model of AK was established. Corneas were collected and analysed by real-time PCR to assess the mRNA levels of TLR 2, 4, myeloid differentiation protein (MyD)88, nuclear factor (NF)-κB, extracellular signal-regulated kinase (ERK), interleukin (IL)-8, tumour necrosis factor (TNF)-α and interferon (IFN) -ß. Immunocytochemistry and Western blot were conducted to examine the proteins of TLR2, TLR4, p-Erk1/2 and p-IκB. Specific inhibitors PDTC and U0126 were used to pretreat the animals to determine the exact receptor and signalling pathway involved in pathogenesis. Expressions of TLR4, MyD88, all three cytokines, NF-κB, p-IκB and p-Erk1/2 were increased in Acanthamoeba-treated rat corneas. PDTC inhibited the production of IL-8 and TNF-α, while U0126 inhibited the synthesis of IFN-ß. TLR4 was involved in sensing the challenge of Acanthamoeba and inducing production of cytokines through TLR4-NF-κB and TLR4-Erk1/2 pathways in corneas of Wistar rats.

Chorismate mutase peptide antibody enables specific detection of Acanthamoeba.

Accurate and rapid diagnosis of Acanthamoeba keratitis (AK) is difficult. Although the diagnostic procedure for AK has improved, further development and effective diagnostic tool utilization for AK need to continue. Chorismate mutase is a key regulatory enzyme involved in the shikimate pathway, a metabolic pathway absent in mammals but central for amino acid biosynthesis in bacteria, fungi, algae, and plants. In this study, we describe the identification and production of a polyclonal peptide antibody targeting chorismate mutase secreted by A. castellanii, which could be used for AK diagnosis. Western blot was performed using the protein lysates and conditioned media of the human corneal epithelial (HCE) cells, non-pathogenic Acanthamoeba, pathogenic Acanthamoeba, clinical isolate of Acanthamoeba spp., and other causes of keratitis such as Fusarium solani, Pseudomonas aeruginosa, and Staphylococcus aureus. Polyclonal antibodies raised against A. castellanii chorismate mutase specifically interacted with lysates of Acanthamoeba origin and their culture media, while such interactions were not observed from other samples. Acanthamoeba-specificity of chorismate mutase was also confirmed using immunocytochemistry after co-culturing Acanthamoeba with HCE cells. Specific binding of the chorismate mutase antibody to Acanthamoeba was observed, which were absent in the case of HCE cells. These results indicate that the chorismate mutase antibody of Acanthamoeba may serve as a method for rapid and differential Acanthamoeba identification.

TLR4: the receptor bridging Acanthamoeba challenge and intracellular inflammatory responses in human corneal cell lines.

Acanthamoeba keratitis (AK) is a painful, vision-threatening infection caused by pathogenic strains of the protozoan, Acanthamoeba. Toll-like receptors (TLRs), which are important components of innate immunity, have an important role in the detection of foreign pathogens and the signaling cascades in host cells. However, no report on the interaction between Acanthamoeba and TLR has been found. In this study we analyzed the role of the TLR and its signaling pathway in human telomerase-immortalized corneal epithelial cells (HUCLs) and stromal fibroblasts (THSFs) challenged by Acanthamoeba. We show that the expressions of TLR4, myeloid differentiation protein 88 (MyD88), nuclear factor (NF)-kappaB, phospho-IkappaB, phospho-extracellular signal-regulated kinases 1/2 (p-Erk1/2) and the inflammatory cytokines interleukin (IL)-8, tumor necrosis factor (TNF)-alpha and interferon (IFN)-beta were significantly increased in Acanthamoeba-treated cells. Pretreatment with anti-TLR antibodies or the specific inhibitors pyrrolidine dithiocarbamate (PDTC) (for the NF-kappaB pathway) and U0126 (for the ERK pathway) was conducted. It was found that anti-TLR4 antibody attenuated the production of cytokines induced by Acanthamoeba infection. PDTC inhibited the production of IL-8 and TNF-alpha whereas U0126 inhibited the synthesis of IFN-beta. Thus, TLR4 is a receptor for Acanthamoeba and exerts an effect through TLR4-MyD88-NF-kappaB and TLR4-ERK1/2 pathways to induce the secretion of cytokines in human corneal cell lines challenged by Acanthamoeba.

Balamuthia and Acanthamoeba-binding antibodies in West African human sera.

Little is known about the prevalence of Balamuthia mandrillaris amoebae and Balamuthia amoebic encephalitis in Africa. As an approach, relative concentrations of amoebae-binding serum antibodies (Ab) were assessed by flow cytometry using formaldehyde-fixed B. mandrillaris, Acanthamoeba lenticulata 72-2 and Acanthamoeba castellanii 1BU amoebae for specific Ab capture (B.m.-Ab, A.l.-Ab, A.c.-Ab). One hundred and ninety-two sera from West African (Côte d'Ivoire) donors aged 11-95years (mean 38 a; 51% males), and living in villages surrounded by rainforest near the Liberian border, were tested and related to reference sera from Berlin. While B.m.-Ab tended to increase with donor age, A.l.-Ab and A.c.-Ab did not. Accordingly, B.m.-Ab correlated only weakly with A.l.-Ab or A.c.-Ab. Of the nine individuals with the highest B.m.-Ab concentrations, most were elderly (mean 58 a), male (78%), and professed intensive outdoor activity (hunting, farming). Only three of these sera also showed elevated A.l.-Ab, and none elevated A.c.-Ab.

Antioxidant defense in the eyes of immunocompetent and immunosuppressed mice infected with Acanthamoeba spp.

BACKGROUND: Acanthamoeba spp. are ubiquitous pathogens which cause granulomatous amoebic encephalitis and disseminated infection. Moreover, Acanthamoeba spp. infection of the cornea leads to Acanthamoeba keratitis. Our previous study showed that the infection of an eyeball may also take place via the migration of trophozoites through the optic nerve from the brain to the eyes. The aim of the study was to analyze the activity of enzymatic antioxidants and the concentration of non-enzymatic antioxidant in the eyes of immunocompetent and immunocompromised mice with disseminated acanthamoebiasis. RESULTS: In the immunocompetent mice infected with Acanthamoeba spp. we noted a significant decrease in catalase activity at 8 and 16 days post-infection (dpi). Glutathione reductase activity was significantly lower at 16 dpi compared to the control group and glutathione concentration was statistically higher at 24 dpi than in the control group. In the immunosuppressed mice, a statistically significant increase in glutathione concentration in the eye samples was found at 16 dpi compared to those not infected with Acanthamoeba spp. In the immunosuppressed mice infected with Acanthamoeba spp., glutathione peroxidase activity was statistically lower at 8 dpi, and glutathione concentration was statistically significantly higher at 16 dpi compared to the control group. CONCLUSIONS: The inflammatory response in the eyes of hosts with experimental acanthamoebiasis led to changes in the activity of enzymatic antioxidants and the content of non-enzymatic antioxidant. Therefore, the dysregulation of antioxidants may play a role in the pathomechanism of Acanthamoeba eye infection.

Can the Environmental Phagocyte Acanthamoeba Be a Useful Model to Study SARS-CoV-2 Pathogenicity, Infectivity, and Evasion of Cellular Immune Defenses?

Acanthamoeba and macrophages exhibit significant parallels in biochemical, physiological, cellular, and functional aspects. Given the ability of Acanthamoeba to contribute to the evolutionary gain of pathogenicity of a variety of microbial pathogens, here we propose the use of Acanthamoeba as a paradigm to study SARS-CoV-2 pathogenicity, infectivity, and evasion of cellular immune defenses.