Neuropathological lesions in intravenous BCG-stimulated K18-hACE2 mice challenged with SARS-CoV-2.

In the wake of the COVID-19 pandemic caused by SARS-CoV-2, questions emerged about the potential effects of Bacillus Calmette-Guérin (BCG) vaccine on the immune response to SARS-CoV-2 infection, including the neurodegenerative diseases it may contribute to. To explore this, an experimental study was carried out in BCG-stimulated and non-stimulated k18-hACE2 mice challenged with SARS-CoV-2. Viral loads in tissues determined by RT-qPCR, histopathology in brain and lungs, immunohistochemical study in brain (IHC) as well as mortality rates, clinical signs and plasma inflammatory and coagulation biomarkers were assessed. Our results showed BCG-SARS-CoV-2 challenged mice presented higher viral loads in the brain and an increased frequency of neuroinvasion, with the greatest differences observed between groups at 3-4 days post-infection (dpi). Histopathological examination showed a higher severity of brain lesions in BCG-SARS-CoV-2 challenged mice, mainly consisting of neuroinflammation, increased glial cell population and neuronal degeneration, from 5 dpi onwards. This group also presented higher interstitial pneumonia and vascular thrombosis in lungs (3-4 dpi), BCG-SARS-CoV-2 mice showed higher values for TNF-α and D-dimer values, while iNOS values were higher in SARS-CoV-2 mice at 3-4 dpi. Results presented in this study indicate that BCG stimulation could have intensified the inflammatory and neurodegenerative lesions promoting virus neuroinvasion and dissemination in this experimental model. Although k18-hACE2 mice show higher hACE2 expression and neurodissemination, this study suggests that, although the benefits of BCG on enhancing heterologous protection against pathogens and tumour cells have been broadly demonstrated, potential adverse outcomes due to the non-specific effects of BCG should be considered.

Protist enteroparasites in wild boar (Sus scrofa ferus) and black Iberian pig (Sus scrofa domesticus) in southern Spain: a protective effect on hepatitis E acquisition?

BACKGROUND: Several studies have independently evaluated the occurrence of hepatitis E virus (HEV) and enteroparasites in swine, but no surveys have been conducted to jointly assess the prevalence and genetic diversity of enteroparasites in pigs and wild boars, their sympatric transmission between hosts, and their potential interaction with HEV. METHODS: We prospectively collected serum and faecal samples from black Iberian domestic pigs and wild boars from southern Spain between 2015‒2016. We evaluated for HEV in serum and faeces, and for the presence of enteroparasites (Giardia duodenalis, Cryptosporidium spp., Blastocystis sp., Neobalantidium coli and Strongyloides spp.) in the same faecal samples. The prevalence of each intestinal parasite species was calculated. RESULTS: A total of 328 animals (56.7% black Iberian pigs and 43.3% wild boars) were included in the study. The overall global prevalence of HEV in serum was 16.8%. The overall global prevalence of each enteroparasite species was 19.5% for G. duodenalis, 8.2% for Cryptosporidium spp., 41.8% for Blastocystis sp., 31.4% for N. coli, and 8.8% for Strongyloides spp. HEV-infected animals showed a significantly lower prevalence of G. duodenalis (3.2 vs 20%; P = 0.002) and Blastocystis sp. (38.7 vs 80%; P < 0.001) than those uninfected by HEV. Animals carrying G. duodenalis and Blastocystis sp. infections showed a significantly lower rate of HEV infection than those not harbouring these enteroparasites (P < 0.001). CONCLUSIONS: Our study found a high prevalence of enteroparasites in black Iberian pigs and wild boars in southern Spain, suggesting a sympatric co-transmission of some of the species investigated. It is suggested that extracellular G. duodenalis and Blastocystis sp. might have a protective effect on HEV acquisition in swine.

Mutations in the Progesterone Receptor (PROGINS) May Reduce the Symptoms of Acute Hepatitis E and Protect Against Infection.

BACKGROUND: Mutations in the progesterone receptor (PR) gene, PROGINS, have been studied in relation to hepatitis E virus (HEV) infection. Patients with the PROGINS gene may develop a worse clinical course of hepatitis E. The aim of our study was to evaluate the influence of PROGINS on the susceptibility to and the clinical course of HEV infection in HIV patients. METHODS: This study included patients with HIV who were evaluated in previous prospective studies for the prevalence and incidence of HEV. The following three groups of patients were studied: (i) never infected, (ii) past infections, and (iii) recently infected. We determined the PR genotype to evaluate the proportion of patients who were homozygous for PROGINS according to HEV infection. We also compared the proportion of PROGINS carriers with a recent HEV infection according to their symptomatology. RESULTS: In this study, 311 patients infected with HIV were included. Of those patients, 198 were homozygous wild type (63.7%), 91 were heterozygous (29.3%), and 22 were homozygous PROGINS (7.1%). We found that the homozygous PROGINS genotype in women was associated with a lower HEV seroprevalence. In addition, in patients with a recent HEV infection, none of those homozygous for PROGINS presented symptoms. CONCLUSION: The PROGINS mutation plays a protective role against HEV infection and is associated with subclinical infection in HIV-infected patients, particularly women.

Risk factors associated with hepatitis E virus in pigs from different production systems.

Pigs are considered important reservoirs of HEV and so constitute a major risk of transmission to humans, either via direct contact or by consuming raw or undercooked contaminated pork products. Once the scale of this disease on European pig farms has been estimated, the identification of risk factors associated with HEV infection in these species could help determine contingency strategies to minimize the risk of transmission to humans. Our objective was to evaluate risk factors associated with HEV in pigs under different production systems. We included 1040 pigs from 26 farms. The prevalence of HEV infection in the study population, evaluated by RT-qPCR, was calculated, then studied according to animal and farm characteristics. Factors associated with HEV infection were analyzed by multivariate analysis. One hundred and seventy-two pigs were infected by HEV, which gave an individual prevalence of 16.5% (95% CI: 14.4%-18.9%). Factors associated with higher prevalence of HEV infection were: extensive farming [23.9%; OR = 2.239 (1.036-4.837)], absence of sanitary ford [33.8%; OR = 3.597 (1.649-7.850)], no quarantine period [20.8%; OR = 2.723 (1.450-5.112)], and contact with domestic species [24.5%; OR = 3.893 (1.453-10.431)]. Our evidence showed that pigs reared on extensive farms are at a higher risk of HEV infection than those reared intensively. The use of control measures could reduce the risk of HEV infection in pigs and minimize the risk of zoonotic transmission.

Proteomic characterisation of bovine and avian purified protein derivatives and identification of specific antigens for serodiagnosis of bovine tuberculosis.

BACKGROUND: Bovine purified protein derivative (bPPD) and avian purified protein derivative (aPPD) are widely used for bovine tuberculosis diagnosis. However, little is known about their qualitative and quantitative characteristics, which makes their standardisation difficult. In addition, bPPD can give false-positive tuberculosis results because of sequence homology between Mycobacterium bovis (M. bovis) and M. avium proteins. Thus, the objective of this study was to carry out a proteomic characterisation of bPPD, aPPD and an immunopurified subcomplex from bPPD called P22 in order to identify proteins contributing to cross-reactivity among these three products in tuberculosis diagnosis. METHODS: Trypsin digests of bPPD, aPPD and P22 were analysed by nanoscale liquid chromatography-electrospray ionization tandem mass spectrometry. Mice were immunised with bPPD or aPPD, and their serum was tested by indirect ELISA for reactivity against these preparations as well as against P22. RESULTS: A total of 456 proteins were identified in bPPD, 1019 in aPPD and 118 in P22; 146 of these proteins were shared by bPPD and aPPD, and 43 were present in all three preparations. Candidate proteins that may cause cross-reactivity between bPPD and aPPD were identified based on protein abundance and antigenic propensity. Serum reactivity experiments indicated that P22 may provide greater specificity than bPPD with similar sensitivity for ELISA-type detection of antibodies against M. tuberculosis complex. CONCLUSION: The subpreparation from bPPD called P22 may be an alternative to bPPD for serodiagnosis of bovine tuberculosis, since it shares fewer proteins with aPPD than bPPD does, reducing risk of cross-reactivity with anti-M. avium antibodies.

Immunohistochemical approach to study cylindrospermopsin distribution in tilapia (Oreochromis niloticus) under different exposure conditions.

Cylindrospermopsin (CYN) is a cytotoxic cyanotoxin produced by several species of freshwater cyanobacteria (i.e., Aphanizomenon ovalisporum). CYN is a tricyclic alkaloid combined with a guanidine moiety. It is well known that CYN inhibits both protein and glutathione synthesis, and also induces genotoxicity and the alteration of different oxidative stress biomarkers. Although the liver and kidney appear to be the main target organs for this toxin based on previous studies, CYN also affects other organs. In the present study, we studied the distribution of CYN in fish (Oreochromis niloticus) under two different exposure scenarios using immunohistochemical (IHC) techniques. In the first method, fish were exposed acutely by intraperitoneal injection or by gavage to 200 µg pure CYN/Kg body weight (bw), and euthanized after 24 h or five days of exposure. In the second method, fish were exposed by immersion to lyophilized A. ovalisporum CYN-producing cells using two concentration levels (10 or 100 µg/L) for two different exposure times (7 or 14 days). The IHC was carried out in liver, kidney, intestine, and gills of fish. Results demonstrated a similar pattern of CYN distribution in both experimental methods. The organ that presented the most immunopositive results was the liver, followed by the kidney, intestine, and gills. Moreover, the immunolabeling signal intensified with increasing time in both assays, confirming the delayed toxicity of CYN, and also with the increment of the dose, as it is shown in the sub-chronic assay. Thus, IHC is shown to be a valuable technique to study CYN distribution in these organisms.