Assessment of Human SARS CoV-2-Specific T-Cell Responses Elicited In Vitro by New Computationally Designed mRNA Immunogens (COVARNA)

The COVID-19 pandemic has brought significant changes and advances in the field of vaccination, including the implementation and widespread use of encapsidated mRNA vaccines in general healthcare practice. Here, we present two new mRNAs expressing antigenic parts of the SARS-CoV-2 spike protein and provide data supporting their functionality. The first mRNA, called RBD-mRNA, encodes a trimeric form of the virus spike protein receptor binding domain (RBD). The other mRNA, termed T-mRNA, codes for the relevant HLA I and II spike epitopes. The two mRNAs (COVARNA mRNAs) were designed to be used for delivery to cells in combination, with the RBD-mRNA being the primary source of antigen and the T-mRNA working as an enhancer of immunogenicity by supporting CD4 and CD8 T-cell activation. This innovative approach substantially differs from other available mRNA vaccines, which are largely directed to antibody production by the entire spike protein. In this study, we first show that both mRNAs are functionally transfected into human antigen-presenting cells (APCs). We obtained peripheral blood mononuclear cell (PBMC) samples from three groups of voluntary donors differing in their immunity against SARS-CoV-2: non-infected (naïve), infected-recovered (convalescent), and vaccinated. Using an established method of co-culturing autologous human dendritic cells (hDCs) with T-cells, we detected proliferation and cytokine secretion, thus demonstrating the ability of the COVARNA mRNAs to activate T-cells in an antigen-specific way. Interestingly, important differences in the intensity of the response between the infected-recovered (convalescent) and vaccinated donors were observed, with the levels of T-cell proliferation and cytokine secretion (IFNγ, IL-2R, and IL-13) being higher in the vaccinated group. In summary, our data support the further study of these mRNAs as a combined approach for future use as a vaccine.

MicroRNA signature from extracellular vesicles of HCV/HIV co-infected individuals differs from HCV mono-infected

Hepatitis C virus (HCV) coinfection with human immunodeficiency virus (HIV) has a detrimental impact on disease progression. Increasing evidence points to extracellular vesicles (EVs) as important players of the host-viral cross-talk. The microRNAs (miRNAs), as essential components of EVs cargo, are key regulators of normal cellular processes and also promote viral replication, viral pathogenesis, and disease progression. We aimed to characterize the plasma-derived EVs miRNA signature of chronic HCV infected and HIV coinfected patients to unravel the molecular mechanisms of coinfection. EVs were purified and characterized from 50 plasma samples (21 HCV mono- and 29 HCV/HIV co-infected). EV-derived small RNAs were isolated and analyzed by massive sequencing. Known and de novo miRNAs were identified with miRDeep2. Significant differentially expressed (SDE) miRNA identification was performed with generalized linear models and their putative dysregulated biological pathways were evaluated. Study groups were similar for most clinical and epidemiological characteristics. No differences were observed in EVs size or concentration between groups. Therefore, HCV/HIV co-infection condition did not affect the concentration or size of EVs but produced a disturbance in plasma-derived EVs miRNA cargo. Thus, a total of 149 miRNAs were identified (143 known and 6 de novo) leading to 37 SDE miRNAs of which 15 were upregulated and 22 downregulated in HCV/HIV co-infected patients. SDE miRNAs regulate genes involved in inflammation, fibrosis, and cancer, modulating different biological pathways related to HCV and HIV pathogenesis. These findings may help to develop new generation biomarkers and treatment strategies, in addition to elucidate the mechanisms underlying virus-host interaction. KEY MESSAGES: HCV and HCV/HIV displayed similar plasma-EV size and concentration. EVs- derived miRNA profile was characterized by NGS. 37 SDE miRNAs between HCV and HCV/HIV were observed. SDE miRNAs regulate genes involved in inflammation, fibrosis and cancer.

Dynamics of HIV Reservoir and HIV-1 Viral Splicing in HCV-Exposed Individuals after Elimination with DAAs or Spontaneous Clearance

Background: Although human immunodeficiency virus type 1 (HIV-1) reservoir size is very stable under antiretroviral therapy (ART), individuals exposed to the Hepatitis C virus (HCV) (chronically coinfected and spontaneous clarifiers) show an increase in HIV reservoir size and in spliced viral RNA, which could indicate that the viral protein regulator Tat is being more actively synthesized and, thus, could lead to a higher yield of new HIV. However, it is still unknown whether the effect of HCV elimination with direct-acting antivirals (DAAs) could modify the HIV reservoir and splicing. Methods: This longitudinal study (48 weeks’ follow-up after sustained virological response) involves 22 HIV+-monoinfected individuals, 17 HIV+/HCV- spontaneous clarifiers, and 24 HIV+/HCV+ chronically infected subjects who eliminated HCV with DAAs (all of them aviremic, viral load < 50). Viral-spliced RNA transcripts and proviral DNA copies were quantified by qPCR. Paired samples were analyzed using a mixed generalized linear model. Results: A decrease in HIV proviral DNA was observed in HIV+/HCV- subjects, but no significant differences were found for the other study groups. An increased production of multiple spliced transcripts was found in HIV+ and HIV+/HCV+ individuals. Conclusions: We conclude that elimination of HCV by DAAs was unable to revert the consequences derived from chronic HCV infection for the reservoir size and viral splicing, which could indicate an increased risk of rapid HIV-reservoir reactivation. Moreover, spontaneous clarifiers showed a significant decrease in the HIV reservoir, likely due to an enhanced immune response in these individuals.

Persistence of hepatitis E virus in the liver of non-viremic naturally infected wild boar

Hepatitis E virus (HEV) is an emerging zoonotic pathogen with pigs and wild boar serving as reservoirs for human infection through direct contact with infected animals or the consumption of raw or undercooked pork products. The liver is considered the main target site of HEV replication in swine and an important organ in the pathogenesis of the disease. The aim of this study was to characterize the target liver cells for HEV entry in naturally infected wild boar and to evaluate the type and severity of the pathological changes in order to reach a better understanding of the hepatic pathogenic mechanisms involved in hepatitis E. In total, 58 livers from hunted wild boar were histopathologically evaluated. The presence of specific HEV antibodies in serum was determined by indirect ELISA. Immunohistochemistry was used for the detection of HEV antigen and Real time RT-PCR to detect HEV RNA in liver and serum. HEV seroprevalence in these animals was of 5.197% (CI_95%: 1.77–14.14). By Real time RT-PCR, HEV was detected in the liver tissue of four wild boar (6.8%; CI_95%: 2.7–16.4) and only one animal was also positive in serum (1.7%; CI_95%: 0.3–9.1). The non-viremic animals naturally infected with HEV presented evidence of liver infection, mainly in Kupffer cells and liver sinusoidal endothelial cells, without apparent associated hepatitis lesions. This study supports the hypothesis that low viral titers may persist in the liver of non-viremic individuals, giving thus the possibility of consumption of contaminated liver of animals diagnosed as HEV-negative in serum. Further immunopathogenic studies are necessary to elucidate the mechanisms responsible for this process and to evaluate the protocols of HEV diagnosis in animals destined for human consumption.