The induction of virus-neutralizing antibodies in influenza A-infected mice treated with Oseltamivir phosphate: effect of dosage and scheduling.

Oseltamivir phosphate (OS) is currently the most frequently used influenza antiviral drug. It moderates the course of influenza virus type A (IAV) infection, however, its impact on the induction of virus-neutralizing antibodies (VNAbs) is not understood in details. Here, we examined the influence of low (10 mg/kg) or high (60 mg/kg) doses of OS on the viral titer in lungs of BALB/c mice infected with 0.5 LD50 of IAV and on the level of VNAbs. Prophylactic application of OS (6 h before the infection) delayed the increase of viral titer in lungs with a lower peak in comparison to non-treated control mice. After therapeutic OS application (44 h after the infection), maximum of virus titer did not significantly change. However, the induction of VNAbs strongly decreased, to 16.7%-18.1% of the control, after preventive application of high OS dose. A minimal decrease of VNAbs titers was observed in groups of mice treated with low dose of OS applied therapeutically. They lowered to 91.1% / 14 or to 94.1% / 21 days post infection (p.i.) of VNAbs titers of non-treated control mice. In all other groups, levels of VNAbs titers dropped to 26.5-53.7% of those of non-treated mice. It should be noted that VNAbs titers were in direct proportion to maximal virus titers in mouse lungs of corresponding groups. In summary, after OS application the clinical symptoms of the disease were milder or non-observable in all OS-treated groups, but the lowering of VNAbs titers was dependent on the OS dose and interval between drug app-lication and the start of infection. Keywords: influenza A virus; Oseltamivir; prophylactic treatment; therapeutic treatment; virus-neutralizing antibodies.

The Contribution of Viral Proteins to the Synergy of Influenza and Bacterial Co-Infection.

A severe course of acute respiratory disease caused by influenza A virus (IAV) infection is often linked with subsequent bacterial superinfection, which is difficult to cure. Thus, synergistic influenza-bacterial co-infection represents a serious medical problem. The pathogenic changes in the infected host are accelerated as a consequence of IAV infection, reflecting its impact on the host immune response. IAV infection triggers a complex process linked with the blocking of innate and adaptive immune mechanisms required for effective antiviral defense. Such disbalance of the immune system allows for easier initiation of bacterial superinfection. Therefore, many new studies have emerged that aim to explain why viral-bacterial co-infection can lead to severe respiratory disease with possible fatal outcomes. In this review, we discuss the key role of several IAV proteins-namely, PB1-F2, hemagglutinin (HA), neuraminidase (NA), and NS1-known to play a role in modulating the immune defense of the host, which consequently escalates the development of secondary bacterial infection, most often caused by Streptococcus pneumoniae. Understanding the mechanisms leading to pathological disorders caused by bacterial superinfection after the previous viral infection is important for the development of more effective means of prevention; for example, by vaccination or through therapy using antiviral drugs targeted at critical viral proteins.

Birds Belonging to the Family Paridae as Another Potential Reservoir of Murine Gammaherpesvirus 68.

Ecology and epidemiology of murine gammaherpesvirus 68 (MHV-68) have been intensively studied since the isolation of the virus from murid rodents in 1976. This virus was detected in various mammalian species that share the biotope with rodent reservoirs of MHV-68. However, a survey of MHV-68 in birds has not so far been performed. Therefore, the aim of this study was to investigate the presence of MHV-68 in blood samples from two bird species captured at four localities in Slovakia. Using the nested PCR targeting ORF50 gene of MHV-68, we confirmed the presence of MHV-68 DNA in 9 out of 57 blood samples from Great tits (Parus major) (prevalence 15.8%, confidence interval [95% CI]: 8.5-27.4) and in 3 out of 43 blood samples from Eurasian blue tits (Cyanistes caeruleus) (prevalence 7.0%, 95% CI: 2.4-18.6). Our results suggest that not only mammals but also birds may serve as reservoirs for MHV-68, providing further evidence that MHV-68 is capable of frequent cross-species transmission.

Wastewater-Based Epidemiology as an Early Warning System for the Spreading of SARS-CoV-2 and Its Mutations in the Population.

New methodologies based on the principle of "sewage epidemiology" have been successfully applied before in the detection of illegal drugs. The study describes the idea of early detection of a virus, e.g., SARS-CoV-2, in wastewater in order to focus on the area of virus occurrence and supplement the results obtained from clinical examination. By monitoring temporal variation in viral loads in wastewater in combination with other analysis, a virus outbreak can be detected and its spread can be suppressed early. The use of biosensors for virus detection also seems to be an interesting application. Biosensors are highly sensitive, selective, and portable and offer a way for fast analysis. This manuscript provides an overview of the current situation in the area of wastewater analysis, including genetic sequencing regarding viral detection and the technological solution of an early warning system for wastewater monitoring based on biosensors.

Quantification of bacteria by in vivo bioluminescence imaging in comparison with standard spread plate method and reverse transcription quantitative PCR (RT-qPCR).

In vivo bioluminescence imaging (BLI) offers a unique opportunity to analyze ongoing bacterial infections qualitatively and quantitatively in intact animals over time, leading to a reduction in the number of animals needed for a study. Since accurate determination of the bacterial burden plays an essential role in microbiological research, the present study aimed to evaluate the ability to quantify bacteria by non-invasive BLI technique in comparison to standard spread plate method and reverse transcription quantitative PCR (RT-qPCR). For this purpose, BALB/c mice were intranasally infected with 1 × 105 CFU of bioluminescent Streptococcus pneumoniae A66.1. At day 1 post-infection, the presence of S. pneumoniae in lungs was demonstrated by spread plate method and RT-qPCR, but not by in vivo BLI. However, on the second day p.i., the bioluminescent signal was already detectable, and the photon flux values positively correlated with CFU counts and RT-qPCR data within days 2-6. Though in vivo BLI is valuable research tool allowing the continuous monitoring and quantification of pneumococcal infection in living mice, it should be kept in mind that early in the infection, depending on the infective dose, the bioluminescent signal may be below the detection limit.

New aromatic 6-substituted 2'-deoxy-9-(ß)-d-ribofuranosylpurine derivatives as potential plant growth regulators.

Cytokinins are naturally occurring substances that act as plant growth regulators promoting plant growth and development, including shoot initiation and branching, and also affecting apical dominance and leaf senescence. Aromatic cytokinin 6-benzylaminopurine (BAP) has been widely used in micropropagation systems and biotechnology. However, its 9-glucoside (BAP9G) accumulates in explants, causing root inhibition and growth heterogenity. To overcome BAP disadvantages, a series of ring-substituted 2'-deoxy-9-(ß)-d-ribofuranosylpurine derivatives was prepared and examined in different classical cytokinin bioassays. Amaranthus, senescence and tobacco callus bioassays were employed to provide details of cytokinin activity of 2'-deoxy-9-(ß)-d-ribosides compared to their respective free bases and ribosides. The prepared derivatives were also tested for their recognition by cytokinin receptors of Arabidopsis thaliana AHK3 and CRE1/AHK4. The ability of aromatic N6-substituted adenine-2'-deoxy-9-(ß)-d-ribosides to promote plant growth and delay senescence was increased considerably and, in contrast to BAP, no loss of cytokinin activity at higher concentrations was observed. The presence of a 2'-deoxyribosyl moiety at the N9-position led to an increase in cytokinin activities in comparison to the free bases and ribosides. The antioxidant capacity, cytotoxicity and effect on the MHV-68 gammaherpesvirus strain were also examined.

IFITM1 expression is crucial to gammaherpesvirus infection, in vivo.

The oncogenic gammaherpesviruses, Epstein-Barr virus (EBV) and Kaposi's sarcoma herpesvirus (KSHV), are etiologically associated with a variety of human cancers, including Burkitt's lymphoma (BL), Hodgkin lymphoma (HL), Kaposi's sarcoma (KS), and primary effusion lymphoma (PEL). Recently, we demonstrated KSHV infection of B- and endothelial cells to significantly upregulate the expression of interferon induced transmembrane protein 1 (IFITM1) which in turn enhances virus entry. This is an extension of the above study. In here, we determined EBV infection of cells to trigger IFITM1 expression, in vitro. Silencing IFITM1 expression using siRNA specifically lowered gammaherpesvirus infection of cells at a post binding stage of entry. A natural model system to explore the effect of IFITM1 on gammaherpesvirus infection in vivo is infection of BALB/c mice with murine gammaherpesvirus 68 (MHV-68). Priming mice with siRNA specific to IFITM1 significantly lowered MHV-68 titers in the lung specimens compared to priming with (NS)siRNA or PBS. MHV-68 titers were monitored by plaque assay and qPCR. Taken together, for the first time, this study provides insight into the critical role of IFITM1 to promoting in vivo gammaherpesvirus infections.

Copper(II) complexes with new fluoroquinolones: Synthesis, structure, spectroscopic and theoretical study, DNA damage, cytotoxicity and antiviral activity.

Copper(II) complexes with fluoroquinolones in the presence of the nitrogen donor heterocyclic ligands 1,10-phenanthroline have been considered in detail. The phenanthroline moiety was introduced into the ligand environment with the aim to determine whether the nuclease activity is feasible. All suitable X-ray structures of the complexes under study reveal a distorted square pyramidal coordination geometry for Cu(II) atom. The conformational and spectroscopic (FT-IR and UV-visible) behavior has been analyzed and has been interpreted with respect to B3LYP/6-311G* calculations including molecular dynamics. The ability of the complexes to cleave DNA was studied by agarose gel electrophoresis with plasmid DNA pBSK+. The results have confirmed that the complexes under study behave as the chemical nucleases. Nuclease like activity in the absence of hydrogen peroxide allows us to deduce an interaction of the complexes with the DNA resulting in the conversion of supercoiled circular DNA to the nicked form. The DNA cleavage activity enhanced by the presence of hydrogen peroxide demonstrates the participation of reactive oxygen species, such as superoxide radical anions and hydroxyl radicals which presence was confirmed independently using the standard radical scavenging agents. It has been suggested that the radical formation through the Fenton/Haber-Weiss reaction is mediated by the redox cycling mechanisms with the participation of cupric/cuprous ions. Cytotoxic activity was evaluated as the 50% cytotoxic concentration (CC50). The potential effects of tested compounds on replication of murine gammaherpesvirus 68 (MHV-68) under in vitro conditions were also evaluated. However, no antiviral activity against MHV-68 was observed.