Fungal co-infection in COVID-19 patients: Should we be concerned?

Critically ill COVID-19 patients have higher pro-inflammatory (IL-1, IL-2, IL-6, tumor necrosis alpha) and anti-inflammatory (IL-4, IL-10) cytokine levels, less CD₄ interferon-gamma expression, and fewer CD₄ and CD₈ cells. This severe clinical situation increases the risk of serious fungal infections, such as invasive pulmonary aspergillosis, invasive candidiasis or Pneumocystis jirovecii pneumonia. However, few studies have investigated fungal coinfections in this population. We describe an update on published reports on fungal coinfections and our personal experience in three Spanish hospitals. We can conclude that despite the serious disease caused by SARS-CoV-2 in many patients, the scarcity of invasive mycoses is probably due to the few bronchoscopies and necropsies performed in these patients because of the high risk in aerosol generation. However, the presence of fungal markers in clinically relevant specimens, with the exception of bronchopulmonary colonization by Candida, should make it advisable to early implement antifungal therapy.     

Human CD8+ T cells transduced with an additional receptor bispecific for both Mycobacterium tuberculosis and HIV‐1 recognize both epitopes

Tuberculosis (TB) and human immunodeficiency virus type 1 (HIV‐1) infection are closely intertwined, with one‐quarter of TB/HIV coinfected deaths among people died of TB. Effector CD8⁺ T cells play a crucial role in the control of Mycobacterium tuberculosis (MTB) and HIV‐1 infection in coinfected patients. Adoptive transfer of a multitude of effector CD8⁺ T cells is an appealing strategy to impose improved anti‐MTB/HIV‐1 activity onto coinfected individuals. Due to extensive existence of heterologous immunity, that is, T cells cross‐reactive with peptides encoded by related or even very dissimilar pathogens, it is reasonable to find a single T cell receptor (TCR) recognizing both MTB and HIV‐1 antigenic peptides. In this study, a single TCR specific for both MTB Ag85B_199‐207 peptide and HIV‐1 Env_120‐128 peptide was screened out from peripheral blood mononuclear cells of a HLA‐A*0201⁺ healthy individual using complementarity determining region 3 spectratype analysis and transferred to primary CD8⁺ T cells using a recombinant retroviral vector. The bispecificity of the TCR gene‐modified CD8⁺ T cells was demonstrated by elevated secretion of interferon‐γ, tumour necrosis factor‐α, granzyme B and specific cytolytic activity after antigen presentation of either Ag85B_199‐207 or Env_120‐128 by autologous dendritic cells. To the best of our knowledge, this study is the first report proposing to produce responses against two dissimilar antigenic peptides of MTB and HIV‐1 simultaneously by transfecting CD8⁺ T cells with a single TCR. Taken together, T cells transduced with the additional bispecific TCR might be a useful strategy in immunotherapy for MTB/HIV‐1 coinfected individuals.     

Intraspecific conflict over host manipulation between different larval stages of an acanthocephalan parasite

Competitive interactions between coinfecting parasites are expected to be strong when they affect transmission success. When transmission is enhanced by altering host behaviour, intraspecific conflict can lead to 'coinfection exclusion' by the first-in parasite or to a 'sabotage' of behavioural manipulation by the youngest noninfective parasite. We tested these hypotheses in the acanthocephalan parasite Pomphorhynchus laevis, reversing phototaxis in its intermediate host Gammarus pulex. No evidence was found for coinfection exclusion in gammarids sequentially exposed to infection. Behavioural manipulation was slightly weakened but not cancelled in gammarids infected with mixed larval stages. Therefore, coinfecting infective and noninfective larvae both suffered competition, potentially resulting in delayed transmission and increased risk of mortality, respectively. Consequently, noninfective larva is not just a 'passive passenger' in the manipulated host, which raises interesting questions about the selective pressures at play and the mechanisms underlying manipulation.     

Multiplicity of infection does not accelerate infectivity evolution of viral parasites in laboratory microcosms

Coinfection with multiple parasite genotypes [multiplicity of infection (MOI)] creates within-host competition and opportunities for parasite recombination and is therefore predicted to be important for both parasite and host evolution. We tested for a difference in the infectivity of viral parasites (lytic phage Φ2) and resistance of their bacterial hosts (Pseudomonas fluorescens SBW25) under both high and low MOI during coevolution in laboratory microcosms. Results show that MOI has no effect on infectivity and resistance evolution during coevolution over ～80 generations of host growth, and this is true when the experiment is initiated with wild-type viruses and hosts, or with viruses and hosts that have already been coevolving for ～330 generations. This suggests that MOI does not have a net effect of accelerating parasite adaptation to hosts through recombination, or slowing adaptation to hosts through between-parasite conflict in this system.     

Decreased memory T-cell response and function in human immunodeficiency virus-infected patients with tegumentary leishmaniasis

The effects of human immunodeficiency virus (HIV) on the immune response in patients with cutaneous leishmaniasis have not yet been fully delineated. This study quantified and evaluated the function of memory T-cell subsets in response to soluble Leishmania antigens (SLA) from patients coinfected with HIV and Leishmania with tegumentary leishmaniasis (TL). Eight TL/HIV coinfected subjects and 10 HIV seronegative subjects with TL were evaluated. The proliferative response of CD4+and CD8+T-cells and naïve, central memory (CM) and effector memory (EM) CD4+T-cells in response to SLA were quantified using flow cytometry. The median cell division indices for CD4+and CD8+T-cells of coinfected patients in response to SLA were significantly lower than those in patients with Leishmania monoinfection (p < 0.05). The proportions of CM and EM CD4+T-cells in response to SLA were similar between the coinfected patients and patients with Leishmania monoinfection. However, the median CM and EM CD4+T-cell counts from coinfected patients were significantly lower (p < 0.05). The reduction in the lymphoproliferative response to Leishmania antigens coincides with the decrease in the absolute numbers of both EM and CM CD4+T-cells in response to Leishmania antigens in patients coinfected with HIV/Leishmania.     

Simultaneous Extraction of Viral and Bacterial Nucleic Acids for Molecular Diagnostic Applications

Molecular detection of microbial pathogens in clinical samples requires the application of efficient sample lysis protocols and subsequent extraction and isolation of their nucleic acids. Here, we describe a simple and time-efficient method for simultaneous extraction of genomic DNA from gram-positive and -negative bacteria, as well as RNA from viral agents present in a sample. This method compared well with existing bacterial- and viral-specialized extraction protocols, worked reliably on clinical samples, and was not pathogen specific. This method may be used to extract DNA and RNA concurrently from viral and bacterial pathogens present in a sample and effectively detect coinfections in routine clinical diagnostics.