Role of interferon gamma in SARS-CoV-2-positive patients with parasitic infections

Abstract

Background By 27 June 2020, almost half a million people had died due to COVID-19 infections. The susceptibility and severity of infection vary significantly across nations. The contribution of chronic viral and parasitic infections to immune homeostasis remains a concern. By investigating the role of interferon (IFN)-γ, we conducted this study to understand the connection between the decrease in numbers and severity of COVID-19 cases within parasitic endemic regions. Our research included 375 patients referred to hospitals for diagnosis of COVID-19 infection. Patients were subjected to full investigations, in particular severe acute respiratory syndrome coronavirus-2 nucleic acid and Toxoplasma IgM and IgG antibody detection, stool examination, and quantitative IFN-γ measurement. Results The majority of the studied cases had chest manifestation either alone (54.7%) or in association with gastrointestinal (GIT) manifestations (19.7%), whereas 25.6% had GIT symptoms. We reported parasitic infections in 72.8% of mild COVID-19 cases and 20.7% of severe cases. Toxoplasma gondii, Cryptosporidium, Blastocyst, and Giardia were the most common parasitic infections among the COVID-19 cases studied. Conclusion The remarkable adaptation of human immune response to COVID-19 infection by parasitic infections with high levels of IFN-γ was observed in moderate cases compared with low levels in extreme cases. The potential therapeutic efforts aimed at the role of parasitic infection in immune system modulation are needed if this hypothesis is confirmed.

A role for T‐cell exhaustion in Long COVID‐19 and severe outcomes for several categories of COVID‐19 patients

“…However, if one or more of these criteria are not satisfied, it is possible for a relatively recent latent pathogen infection, or a latent pathogen infection producing little inflammation or a low titer of antigens, to induce very little or no T-cell exhaustion. Furthermore, if some circumstance or treatment can block T-cell exhaustion that reduces T-cell functions, some latent pathogen infections, including some types of protozoan parasite infections, can induce CD4 T-cells and CD8 T-cells to release higher levels of antiviral interferonγ that can promote an improved response to a later infection by a virus(Abdel-Hamed et al, 2021;Bhadra et al, 2011).A recent paper summarized a clinical study of 375 COVID-19 patients in Egypt and the relationship between their SARS-CoV-2 viral infection outcomes and the presence in almost 69% of the patients of various protozoan parasite infections, including T. gondii(Abdel- Hamed et al, 2021). However, there was no indication of whether any of these patients had received early drug treatments for their protozoan parasite infections that would have blocked later T-cell exhaustion(Abdel-Hamed et al, 2021).…”

“…Furthermore, if some circumstance or treatment can block T-cell exhaustion that reduces T-cell functions, some latent pathogen infections, including some types of protozoan parasite infections, can induce CD4 T-cells and CD8 T-cells to release higher levels of antiviral interferonγ that can promote an improved response to a later infection by a virus(Abdel-Hamed et al, 2021;Bhadra et al, 2011).A recent paper summarized a clinical study of 375 COVID-19 patients in Egypt and the relationship between their SARS-CoV-2 viral infection outcomes and the presence in almost 69% of the patients of various protozoan parasite infections, including T. gondii(Abdel- Hamed et al, 2021). However, there was no indication of whether any of these patients had received early drug treatments for their protozoan parasite infections that would have blocked later T-cell exhaustion(Abdel-Hamed et al, 2021). This clinical study concluded that the protozoan parasite stimulation of T-cells significantly increased the levels of interferonγ, and that existing protozoan parasite infections with increased levels of interferonγ resulted in a large majority of cases with more moderate COVID-19 symptoms(Abdel-Hamed et al, 2021).…”

The role of polyspecific T-cell exhaustion in severe outcomes for COVID-19 patients having latent pathogen infections such as Toxoplasma gondii

“…The fundamental observations below regarding major genetic variations in virulence and early drug treatment effects could also be relevant to several other bacterial, viral and fungal pathogens, and protozoan parasites including Cryptosporidium parvum, C. hominis , Blastocyst spp., Giardia lamblia (i.e., Giardia duodenalis) , and Entamoeba histolytica, etc. [ 8 ].…”

“…Two papers have also suggested COVID-19 can reactivate latent pathogens, such as Toxoplasma gondii [ 6 , 7 ]. However, other papers claim that latent pathogen infections, including protozoan parasite infections such as T. gondii , can exert antiviral effects by increasing the production of type I or type II interferons and can reduce the severity of COVID-19 and other viral infections [ [8] , [9] , [10] ].…”

SARS-CoV-2 infection and parasitic diseases: A possible role for microbiome interaction?

“…It has even been demonstrated a decreased incidence and severity of COVID-19 in patients with parasitic infections ( Cryptosporidium, T. gondii, Blastocyst, and Giardia ) compared with those who had SARS-CoV-2 infection alone, supporting a protective role of parasitic infections against COVID-19 [ 7 ]. Furthermore, high levels of IFN-γ characterized mild cases, compared with low levels in severe cases of COVID-19 with parasitic infections.…”