[Antiviral and virucidal activity of sodium deoxyribonucleate and its complex with iron against viruses of different kingdoms and families]

INTRODUCTION

The urgent problem of modern medicine is the fight against acute respiratory viral infections (ARVI). To combat ARVI, drugs of wide antiviral potency are needed, as well as immunomodulating drugs. Such antiviral and immunomodulatory effects has sodium deoxyribonucleate (DNA-Na) and its complex with iron (DNA-Na-Fe) developed on the basis of double-stranded DNA of natural origin.

AIM OF THE STUDY

To assess antiviral and virucidal activity of DNA-Na and DNA-Na-Fe against viruses of different kingdoms and families.

MATERIALS AND METHODS

Antiviral and virucidal activity of DNA-Na and DNA-Na-Fe was assessed in cell cultures infected with viruses.

RESULTS AND DISCUSSION

DNA-Na and DNA-Na-Fe had antiviral activity against adenovirus at concentrations of 2501000 mcg/ml. Antiviral effect of both drugs was not detected in case of poliovirus. DNA-Na and DNA-Na-Fe had antiviral activity against coronavirus in all administration schemes. EC50 for DNA-Na ~ 2500 mcg/ml, for DNA-Na-Fe ~ 1000 mcg/ml. In cells treated with DNA-Na-Fe, secretion of following proinflammatory cytokines was detected: Interleukin (IL) 1, IL-2, IL-6, IL-18, interferon- (IFN-), IFN-, as well as anti-inflammatory cytokines: IL-4, IL-10, antagonist of IL-1 receptor. Evidently, DNA-Na and DNA-Na-Fe have antiviral effect, but mechanism of action does not seem to be associated with specific effect on viral replication. Presence of virucidal activity of drugs against representatives of Coronaviridae, Adenoviridae, Picornaviridae, Retroviridae, Herpesviridae in vitro test in range of 1.03.0 lg TCID50 was identified.

CONCLUSION

Presence of simultaneous antiviral and virucidal activity of DNA-Na and DNA-Na-Fe against adeno- and coronaviruses shows their prospects for prevention and treatment of ARVI.

ICTV Virus Taxonomy Profile: Retroviridae 2021

Viruses in the family Retroviridae are found in a wide variety of vertebrate hosts. Enveloped virions are 80-100 nm in diameter with an inner core containing the viral genome and replicative enzymes. Core morphology is often characteristic for viruses within the same genus. Replication involves reverse transcription and integration into host cell DNA, resulting in a provirus. Integration into germline cells can result in a heritable provirus known as an endogenous retrovirus. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Retroviridae, which is available at ictv.global/report/retroviridae.

Equine Infectious Anemia Virus (EIAV): Evidence of Circulation in Donkeys from the Brazilian Northeast Region

Equine infectious anemia (EIA) is listed by the World Organization for Animal Health (OIE) as one of the equine diseases that must be notified. No effective treatment or vaccine is available. EIA control is based on segregation and euthanasia of positive equids. The disease is caused by the equine infectious anemia virus (EIAV), a member of the genus Lentivirus of the Retroviridae family. Despite the importance of this disease in equids, EIA has been poorly studied in donkeys (Equus asinus). We evaluate the sanitary conditions related to EIAV in donkeys from a shelter of abandoned animals captured on the roads of the Ceará. A total of 124 donkeys were randomly selected, and three horses lived at the same shelter. The animals were clinically evaluated, and a group of the 20 animals was submitted to hematological tests. Three diagnostic tests for EIA were used, agar gel immunodiffusion (AGID), enzyme-linked immunosorbent assay (ELISA) using EIAV recombinant protein gp90 (rgp90) and recombinant protein p26 (rp26) ELISA, and polymerase chain reaction (PCR) for detection of the EIAV tat-gag gene. From the donkeys, only 1 animal was positive using AGID 0.81% (1/124), compared to 21.8% (27/124) in the rgp90 and 10.5% (13/124) in the rp26 ELISA. Proviral DNA was detected by PCR tat-gag in 8.8% (11/124), and phylogenetic analysis confirms that the EIAV sequences of donkeys from the Brazilian Northeast grouped with Pantanal Brazilian sequences. Thus, in light of the results, we conclude that donkeys are carriers of EIAV and could be sources of infection.

Influence of the amino-terminal sequence on the structure and function of HIV integrase

Background

Antiretroviral therapy (ART) can mitigate the morbidity and mortality caused by the human immunodeficiency virus (HIV). Successful development of ART can be accelerated by accurate structural and biochemical data on targets and their responses to inhibitors. One important ART target, HIV integrase (IN), has historically been studied in vitro in a modified form adapted to bacterial overexpression, with a methionine or a longer fusion protein sequence at the N-terminus. In contrast, IN present in viral particles is produced by proteolytic cleavage of the Pol polyprotein, which leaves a phenylalanine at the N-terminus (IN 1F). Inspection of available structures suggested that added residues on the N-terminus might disrupt proper protein folding and formation of multimeric complexes.

Results

We purified HIV-1 IN 1F^1–212 and solved its structure at 2.4 Å resolution, which showed extension of an N-terminal helix compared to the published structure of IN^1–212. Full-length IN 1F showed increased in vitro catalytic activity in assays of coupled joining of the two viral DNA ends compared to two IN variants containing additional N-terminal residues. IN 1F was also altered in its sensitivity to inhibitors, showing decreased sensitivity to the strand-transfer inhibitor raltegravir and increased sensitivity to allosteric integrase inhibitors. In solution, IN 1F exists as monomers and dimers, in contrast to other IN preparations which exist as higher-order oligomers.

Conclusions

The structural, biochemical, and biophysical characterization of IN 1F reveals the conformation of the native HIV-1 IN N-terminus and accompanying unique biochemical and biophysical properties. IN 1F thus represents an improved reagent for use in integration reactions in vitro and the development of antiretroviral agents.

Recent Advances in the Development of Integrase Inhibitors for HIV Treatment

PURPOSE OF THE REVIEW

The complex multistep life cycle of HIV allows it to proliferate within the host and integrate its genome in to the host chromosomal DNA. This provirus can remain dormant for an indefinite period. The process of integration, governed by integrase (IN), is highly conserved across the Retroviridae family. Hence, targeting integration is not only expected to block HIV replication but may also reveal new therapeutic strategies to treat HIV as well as other retrovirus infections.

RECENT FINDINGS

HIV integrase (IN) has gained attention as the most promising therapeutic target as there are no equivalent homologues of IN that has been discovered in humans. Although current nano-formulated long-acting IN inhibitors have demonstrated the phenomenal ability to block HIV integration and replication with extraordinary half-life, they also have certain limitations. In this review, we have summarized the current literature on clinically established IN inhibitors, their mechanism of action, the advantages and disadvantages associated with their therapeutic application, and finally current HIV cure strategies using these inhibitors.

Retrovirus-Mediated Transfection of the Tissue-type Plasminogen Activator Gene Results in Increased Thrombolysis of Blood Clots

Tissue-type plasminogen activator (tPA) is involved in the lysis of blood clots. In this study, we attempted to target thrombolysis and enhance blood clot lysis by generating a construct (pLEGFP-N1-tPA) to integrate tPA gene into the genome of different cell lines. pLEGFP-N1-tPA construct was generated and used to target the tPA gene in different cell lines. The thrombolytic effects mediated by the supernatant from transfected HeLa cells and Linx cells were assessed using plasma thrombus plates. Furthermore, enhanced green fluorescent protein (EGFP), which was fused to the tPA gene in the pLEGFP-N1-tPA construct, was analyzed under the fluorescent microscope to assess tPA localization. We also monitored tPA activity and expression in the transfected cell lines. As part of the study, we successfully generated the pLEGFP-N1-tPA construct. The sequence of this construct was verified and the construct was subsequently used to generate the PT67/pLEGFP-N1-tPA cell line. The pLEGFP-N1-tPA construct was also used to transfect HeLa cells and Linx cells. We observed that supernatants from transfected cells were capable of lysing thrombi. In addition, tPA activity and tPA concentration were elevated in the latter supernatants and tPA was rapidly and stably expressed in the transfected cell lines. These results reveal a potentially important thrombolytic role for tPA-targeted gene therapy following cardiac valve replacement.

Analysis of swine leukocyte antigen class I gene profiles and porcine endogenous retrovirus viremia level in a transgenic porcine herd inbred for xenotransplantation research

Molecular characterization of swine leukocyte antigen (SLA) genes is important for elucidating the immune responses between swine-donor and human-recipient in xenotransplantation. Examination of associations between alleles of SLA class I genes, type of pig genetic modification, porcine endogenous retrovirus (PERV) viral titer, and PERV subtypes may shed light on the nature of xenograft acceptance or rejection and the safety of xenotransplantation. No significant difference in PERV gag RNA level between transgenic and non-transgenic pigs was noted; likewise, the type of applied transgene had no impact on PERV viremia. SLA-1 gene profile type may correspond with PERV level in blood and thereby influence infectiveness. Screening of pigs should provide selection of animals with low PERV expression and exclusion of specimens with PERV-C in the genome due to possible recombination between A and C subtypes, which may lead to autoinfection. Presence of PERV-C integrated in the genome was detected in 31.25% of specimens, but statistically significant increased viremia in specimens with PERV-C was not observed. There is a need for multidirectional molecular characterization (SLA typing, viremia estimation, and PERV subtype screening) of animals intended for xenotransplantation research in the interest of xeno-recipient safety.

Native structure of a retroviral envelope protein and its conformational change upon interaction with the target cell

Enveloped viruses enter their host cells by membrane fusion. The process of attachment and fusion in retroviruses is mediated by a single viral envelope glycoprotein (Env). Conformational changes of Env in the course of fusion are a focus of intense studies. Here we provide further insight into the changes occurring in retroviral Env during its initial interaction with the cell, employing murine leukemia virus (MLV) as model system. We first determined the structure of both natively membrane anchored MLV Env and MLV Env tagged with YFP in the proline rich region (PRR) by electron cryo tomography (cET) and sub-volume averaging. At a resolution of ∼20 Å, native MLV Env presents as a hollow trimer (height ∼85 Å, diameter ∼120 Å) composed of step-shaped protomers. The major difference to the YFP-tagged protein was in regions outside of the central trimer. Next, we focused on elucidating the changes in MLV Env upon interaction with a host cell. Virus interaction with the plasma membrane occurred over a large surface and Env clustering on the binding site was observed. Sub-volume averaging did yield a low-resolution structure of Env interacting with the cell, which had lost its threefold symmetry and was elongated by ∼35 Å in comparison to the unbound protein. This indicates a major rearrangement of Env upon host cell binding. At the site of virus interaction, the otherwise clearly defined bilayer structure of the host cell plasma membrane was much less evident, indicative of integral membrane protein accumulation and/or a change in membrane lipid composition.

Endogenous Retroviruses in the Genomics Era

Endogenous retroviruses comprise millions of discrete genetic loci distributed within the genomes of extant vertebrates. These sequences, which are clearly related to exogenous retroviruses, represent retroviral infections of the deep past, and their abundance suggests that retroviruses were a near-constant presence throughout the evolutionary history of modern vertebrates. Endogenous retroviruses contribute in myriad ways to the evolution of host genomes, as mutagens and as sources of genetic novelty (both coding and regulatory) to be acted upon by the twin engines of random genetic drift and natural selection. Importantly, the richness and complexity of endogenous retrovirus data can be used to understand how viruses spread and adapt on evolutionary timescales by combining population genetics and evolutionary theory with a detailed understanding of retrovirus biology (gleaned from the study of extant retroviruses). In addition to revealing the impact of viruses on organismal evolution, such studies can help us better understand, by looking back in time, how life-history traits, as well as ecological and geological events, influence the movement of viruses within and between populations.

Lentiviral vectors and cystic fibrosis gene therapy

Cystic fibrosis (CF) is a chronic autosomic recessive syndrome, caused by mutations in the CF Transmembrane Conductance Regulator (CFTR) gene, a chloride channel expressed on the apical side of the airway epithelial cells. The lack of CFTR activity brings a dysregulated exchange of ions and water through the airway epithelium, one of the main aspects of CF lung disease pathophysiology. Lentiviral (LV) vectors, of the Retroviridae family, show interesting properties for CF gene therapy, since they integrate into the host genome and allow long-lasting gene expression. Proof-of-principle that LV vectors can transduce the airway epithelium and correct the basic electrophysiological defect in CF mice has been given. Initial data also demonstrate that LV vectors can be repeatedly administered to the lung and do not give rise to a gross inflammatory process, although they can elicit a T cell-mediated response to the transgene. Future studies will clarify the efficacy and safety profile of LV vectors in new complex animal models with CF, such as ferrets and pigs.

Construction of retroviral vectors to induce a strong expression of human class interferon gene in human hepatocellular carcinoma cells in vitro

AIM: To establish the hepatoma cell–specific expression of human interferon (IFN) gene mediated by retroviral vectors

METHODS: Human interferon α and interferon β complementary DNA (IFN cDNA) were cloned into the polylinker site of pMNSM retroviral vector to construct recombinant retroviral vectors pMNSIFNA and pMNSIFNB, with the transcription of IFN gene being driven by Simian virus 40 early region promoter (SV40) early region promoter. IFN cDNAs were also cloned into pMNAIFNA, pAMNSIFNA, and pMNAIFNB, with the transcription of IFN gene being driven by SV40 early region promoter regulated by α-fetoprotein enhancer. Next, the retroviral constructs were introduced into retroviral amphotropic packaging cells using the lipofectamine-mediated gene transfer procedure. The rate of plasmid transfection was (4-40) × 10³ colonies/μg DNA/10⁶ PA317 cells. The rate of retrovirus infection was (5-500) × 10⁴ colony forming units (CFU)/mL. Further, the recombinant retroviruses were used to infect human hepatoma cells, renal carcinoma cells, and melanoma cell lines in the presence of 4 μmg/L polybrene.

RESULTS: Northern and Dot hybridization of total RNA from the neomycin-resistant colonies and IFN expression assay indicated that human α fetoprotein enhancer induced efficient and specific transcription and expression of IFN genes driven by the promoter of different origins in human hepatoma cells, leading to high production of α fetoprotein.

CONCLUSION: Cis active element of α-fetoprotein gene can drive specific expression of IFN genes in human hepatoma cells, which provides some valuable data for the hepatoma-specific immune gene therapy.