Recurrence is a hallmark of ocular toxoplasmosis (OT), and conditions that influence its occurrence remain a challenge. Natural killer cells (NK) are effectors cells whose primary is cytotoxic function against many parasites, including Toxoplasma gondii. Among the NK cell receptors, immunoglobulin-like receptors (KIR) deserve attention due to their high polymorphism. This study aimed to analyse the influence of KIR gene polymorphism in the course of OT infection and its association with recurrences after an active episode. Ninety-six patients from the Ophthalmologic Clinic of the National Institute of Infectology Evandro Chagas were followed for up to five years. After DNA extraction, genotyping of the patients was performed by polymerase chain reaction sequence-specific oligonucleotide (PCR-SSO) utilising Luminex equipment for reading. During follow-up, 60.4% had a recurrence. We identified 25 KIR genotypes and found a higher frequency of genotype 1 (31.7%) with worldwide distribution. We note that the KIR2DL2 inhibitor gene and the gene activator KIR2DS2 were more frequent in patients without recurrence. Additionally, we observed that individuals who carry these genes progressed recurrence episodes slowly compared to individuals who do not carry these genes. The KIR2DL2 and KIR2DS2 are associated as possible protection markers against ocular toxoplasmosis recurrence (OTR).

Neurodegenerative diseases (NDs) are increasingly common, especially in populations with higher life expectancies. They are associated mainly with protein metabolism and structure changes, leading to neuronal cell death. Viral infections affect these cellular processes and may be involved in the etiology of several neurological illnesses, particularly NDs. Enteroviruses (EVs) frequently infect the central nervous system (CNS), causing neurological disease. Inflammation, disruption of the host autophagy machinery, and deregulation and accumulation/misfolding of proteins are the main alterations observed after infection by an EV. In this perspective, we discuss the most recent findings on the subject, examining the possible role of EVs in the development of NDs, and shedding light on the putative role played by these viruses in developing NDs.

Innate immunity refers to the mechanisms responsible for the first line of defense against pathogens, cancer cells and toxins. The innate immune system is also responsible for the initial activation of the body's specific immune response (adaptive immunity). Innate immunity was studied and further developed in parallel with adaptive immunity beginning in the first half of the 19th century and has been gaining increasing importance to our understanding of health and disease. In the present overview, we describe the main findings and ideas that contributed to the development of innate immunity as a continually expanding branch of modern immunology. We start with the toxicological studies by Von Haller and Magendie, in the late 18th and early 19th centuries, and continue with the discoveries in invertebrate immunity that supported the discovery and characterization of lipopolysaccharide (LPS) and pattern recognition receptors that led to the development of the pattern recognition and danger theory.

Dengue is a disease caused by dengue virus (DENV-1 through -4). Among the four serotypes, DENV-4 remains the least studied. Acute kidney injury is a potential complication of dengue generally associated with severe dengue infection.The goal of this study was to investigate the alterations caused by experimental dengue infection in the kidney of adult BALB/c mice.In this study, BALB/c mice were infected through the intravenous route with a DENV-4 strain, isolated from a human patient. The kidneys of the mice were procured and subject to histopathological and ultrastructural analysis.The presence of the viral antigen was confirmed through immunohistochemistry. Analysis of tissue sections revealed the presence of inflammatory cell infiltrate throughout the parenchyma. Glomerular enlargement was a common find. Necrosis of tubular cells and haemorrhage were also observed. Analysis of the kidney on a transmission electron microscope allowed a closer look into the necrotic tubular cells, which presented nuclei with condensed chromatin, and loss of cytoplasm.Even though the kidney is probably not a primary target of dengue infection in mice, the inoculation of the virus in the blood appears to damage the renal tissue through local inflammation.

The World Health Organization (WHO) roadmap and recommendations for elimination of schistosomiasis were recently updated. With significant reductions in the prevalence and intensity of schistosomiasis infections worldwide, there is a need for more sensitive diagnostic methods. There are a few remaining transmission hotspots in Brazil, although low endemicity settings comprise most of the endemic localities. For the latter, serology may represent a tool for population screening which could help eliminate transmission of schistosomiasis. Here, we review serology tests currently available in Brazil from both public health and private laboratories: immunofluorescent antibody tests (IFATs) on adult worm sections and enzyme-linked immunosorbent assays (ELISAs) with soluble egg and adult worm antigens. Both in-house and commercially available tests have received less than adequate performance evaluations. Our review of immediate basic and operational research goals may help identify local adjustments that can be made to improve control interventions aimed at elimination of schistosomiasis as a public health problem.

The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants can infect common mice inducing significant pathological lung lesions and inflammatory responses. This substantially mimics coronavirus disease 19 (COVID-19) infection and pathogenesis in humans. To characterise the effects of recombinant SARS-CoV-2 S1 receptor-binding domain (RBD) peptide in murine macrophage and microglial cells' immune activation compared with classical PAMPs in vitro. Murine RAW 264.7 macrophages and BV2 microglial cells were exposed to increasing concentrations of the RBD peptide (0.01, 0.05, and 0.1 µg/mL), Lipopolysaccharide (LPS) and Poly(I:C) and evaluated after two and 24 h for significant markers of macrophage activation. We determined the effects of RBD peptide on cell viability, cleaved caspase 3 expressions, and nuclear morphometry analysis. In RAW cells, RBD peptide was cytotoxic, but not for BV2 cells. RAW cells presented increased arginase activity and IL-10 production; however, BV2 cells expressed iNOS and IL-6 after RBD peptide exposure. In addition, RAW cells increased cleaved-caspase-3, apoptosis, and mitotic catastrophe after RBD peptide stimulation but not BV2 cells. RBD peptide exposure has different effects depending on the cell line, exposure time, and concentration. This study brings new evidence about the immunogenic profile of RBD in macrophage and microglial cells, advancing the understanding of SARS-Cov2 immuno- and neuropathology.

Epidemiological data related to leishmaniases or Leishmania infection in horses are scarce. However, studies carried out in different regions in the world showed equids parasitised by Leishmania braziliensis, L. infantum and L. martiniquensis.Identify the Leishmania species causing cutaneous leishmaniasis in a mare, living in Rio de Janeiro State (Brazil), and search the presence of Leishmania viruses in the isolated parasite.Isoenzymes and polymerase chain reaction (PCR) targeting ITSrDNA region followed by sequencing were conducted for typing the isolated parasite. A search for Leishmania virus infection was also performed.The mare presented skin nodules and ulcers in the left pinna caused by Leishmania spp. that was detected by culture and PCR. The parasite was identified as Leishmania (Mundinia) martiniquensis, infected by Leishbunyavirus (LBV), representing the first description of this species in South America. The animal travelled to different Brazilian regions, but not to outside the country.The worldwide distribution of L. martiniquensis and its infection by LBV were confirmed in this study, indicating the autochthonous transmission cycle in Brazil. The clinical profile of the disease in the mare, showing fast spontaneous healing of cutaneous lesions, may indicate that skin lesions related to L. martiniquensis infection in horses might be underdiagnosed.

Dendritic cells (DCs) specific intercellular adhesion molecule (ICAM)-3-grabbing non integrin receptor (DC-SIGN) binds to subgenera Leishmania promastigotes mediating its interaction with DC and neutrophils, potentially influencing the infection outcome. In this work, we investigated whether DC-SIGN receptor is expressed in cells from cutaneous leishmaniasis (CL) lesions as well as the in vitro binding pattern of Leishmania (Viannia) braziliensis (Lb) and L. (L.) amazonensis (La) promastigotes. DC-SIGN receptor was labeled by immunohistochemistry in cryopreserved CL tissue fragments. In vitro binding assay with CFSE-labeled Lb or La promastigotes and RAJI-transfecting cells expressing DC-SIGN (DC-SIGNPOS) or mock-transfected (DC-SIGNNEG) were monitored by flow cytometry at 2 h, 24 h and 48 h in co-culture. In CL lesion infiltrate, DC-SIGNPOS cells were present in the dermis and near the epidermis. Both Lb and La bind to DC-SIGNPOS cells, while binding to DC-SIGNNEG was low. La showed precocious and higher affinity to DC-SIGNhi population than to DC-SIGNlow, while Lb binding was similar in these populations. Our results demonstrate that DC-SIGN receptor is present in L. braziliensis CL lesions and interact with Lb promastigotes. Moreover, the differences in the binding pattern to Lb and La suggest DC-SIGN can influence in a difference way the intake of the parasites at the first hours after Leishmania infection. These results raise the hypothesis that DC-SIGN receptor could participate in the immunopathogenesis of American tegumentary leishmaniasis accounting for the differences in the outcome of the Leishmania spp. infection.