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.

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.

Background. Cyclin-dependent kinase 8 (CDK8) is a multifaceted regulator and represents a catalytic component of the transcriptional Mediator complex. CDK8 activity, on the one hand, increases transcriptional elongation by the recruitment of Mediator/super elongation complexes, but, on the other hand, negatively regulates CDK7-controlled transcriptional initiation through inactivating cyclin H phosphorylation. Recently, these combined properties of CDK8 have also suggested its rate-limiting importance for herpesviral replication. Objectives. In this paper, we focused on human cytomegalovirus (HCMV) and addressed the question of whether the pharmacological inhibition or knock-down of CDK8 may affect viral replication efficiency in cell culture models. Methods. A number of human and animal herpesviruses, as well as non-herpesviruses, were used to analyze the importance of CDK8 for viral replication in cell culture models, and to assess the antiviral efficacy of CDK8 inhibitors. Results. Using clinically relevant CDK8 inhibitors (CCT-251921, MSC-2530818, and BI-1347), HCMV replication was found strongly reduced even at nanomolar drug concentrations. The EC₅₀ values were consistent for three different HCMV strains (i.e., AD169, TB40, and Merlin) analyzed in two human cell types (i.e., primary fibroblasts and astrocytoma cells), and the drugs comprised a low level of cytotoxicity. The findings highlighted the following: (i) the pronounced in vitro SI values of anti-HCMV activity obtained with CDK8 inhibitors; (ii) a confirmation of the anti-HCMV efficacy by CDK8–siRNA knock-down; (iii) a CDK8-dependent reduction in viral immediate early, early, and late protein levels; (iv) a main importance of CDK8 for viral late-stage replication; (v) several mechanistic aspects, which point to a strong impact on viral progeny production and release, but a lack of CDK8 relevance for viral entry or nuclear egress; (vi) a significant anti-HCMV drug synergy for combinations of inhibitors against host CDK8 and the viral kinase vCDK/pUL97 (maribavir); (vii) finally, a broad-spectrum antiviral activity, as seen for the comparison of selected α-, β-, γ-, and non-herpesviruses. Conclusions. In summary, these novel data provide evidence for the importance of CDK8 as a positive regulator of herpesviral replication efficiency, and moreover, suggest its exploitability as an antiviral target for novel strategies of host-directed drug development.

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.

Human herpesviruses represent major human pathogens. Members of the γ-Herpesvirinae subfamily are of particular interest because they cause chronic diseases, such as cancers, by altering cellular processes and driving resting cells into a continuously proliferating phase. Also autoimmune diseases have continuously been in the focus of interest, such as multiple sclerosis. The prototypic human γ-herpesvirus, Epstein-Barr virus (EBV), has proven difficult to analyze for the development of antiviral therapies due to challenges associated with in vitro virus propagation, phenotyping, and assessment of antiviral phenotypic efficacy. The murine γ-herpesvirus 68 (MHV-68) is a well-characterized homolog of EBV and represents a model virus for cell culture-based and animal model analyses. Here, we used MHV-68 to determine virus sensitivity to antivirals, and combinatorial drug synergies. Much of the recent information about novel antiherpesviral drugs has come from studies of human cytomegalovirus (HCMV). Therefore, a comparative analysis was also conducted between HCMV, MHV-68, and EBV. The study demonstrated: (i) successful establishment of a new MHV-68 replication model in murine and non-murine cell types; (ii) optimization of an MHV-68-specific quantitative readout based on the luciferase reporter system; (iii) assessment of mechanistically novel antiherpesviral compounds; (iv) comparative antiviral effects spanning the three respective herpesviruses; (v) analysis of antiviral drug combination treatments able to identify statistically significant drug synergies. Overall, the study provides new insights into molecular aspects of γ-herpesvirus replication as well as antiviral drug development and targeting strategies.