Recently, previously known viruses have changed their pathogenicity and encompassed new types of host populations. An example of such an infection is that caused by SARS-CoV, belonging to the “well-known” coronavirus family. Another group of viruses that are of great importance to the human population are the herpes viruses. Due to increasing viral resistance to existing antiviral drugs, plant extracts are attracting increasing interest due to their complex composition and their simultaneous attack of different viral targets. Based on the above, we tested the antiviral potential of water–alcoholic extract obtained from a commercial sample of the plant Cistus incanus L. against the enveloped viruses SvHA1, SvHA2 (ACV resistant) and HCoV 229E. The results showed both complete inhibition of the intracellular stages of the viral replication and a strong effect on extracellular virions in the three viral models. In a study of the effect on the replication of SvHA 2, the calculated selectivity index was over 10. From the experiments on the virucidal effects on the two herpes viruses, it was found that the viral titer of the samples decreased by about 4 lg compared to the control sample. The extract is of interest for introduction into practice.

Adenoviruses are detected in wastewater at significantly higher frequencies than most other enteric viruses. The aim of this study was to determine the abundance of human adenoviruses in samples collected from wastewater treatment plants in Sofia, Plovdiv, Burgas, and Varna using quantitative PCR (qPCR). During the study period in 2024, one or two peaks in adenovirus levels were detected in each city, with viral loads ranging from 10 to 30,000 genome copies/mL. Selected wastewater samples from Sofia were used to inoculate three different cell lines. Productive adenovirus replication was observed only in the Vero E6 cell line. Shotgun sequencing of DNA extracted from infected cells enabled the assembly of six complete adenovirus genomes from three qPCR-positive samples. Taxonomic analysis identified viruses belonging to the Mastadenovirus adami, Mastadenovirus blackbeardi, Mastadenovirus caesari, and Mastadenovirus dominans species, with the predominant genotype (three of six genomes) showing the highest similarity to HAdV-A31. Comparative genomic analysis provided evidence of molecular evolution driven by multiple recombination events. The recovered genomes contained hypervariable regions composed of genetic elements closely related to genotypes previously reported from different geographical regions. Overall, the integrated approach employed in this study demonstrates the value of combining wastewater surveillance, virus isolation, and whole-genome sequencing to monitor adenovirus circulation, characterize dominant variants, and assess their potential clinical significance.

The toxicological risk and development of resistance associated with synthetic drugs and supplements can be reduced by focusing efforts on medicinal plants that are of interest in pharmacognostic research to find new drugs or templates for the development of new bioactive compounds. The parasitic plant Cuscuta spp. has significant pharmacological activity at the extract level, but there is limited data on the bioactivity of its chemical compounds. In the present study, we aimed to investigate the antiviral potential of extracts obtained from different parts of two species, C. campestris and C. epithymum. The two species clearly differ in their flavonoid profiles, which could also suggest different antiviral activities of the extracts. We used methanol and aqueous extracts, MDBK, VERO E6 clone 76 and BGM cell lines, HSV-1, HSV-2 strain DD (acyclovir-resistant), HCoV-229E and SARS-CoV-2, maximum tolerable concentration, the MTT test, the plaque-forming method and the HPLS-MS analysis. It was found that the metabolic composition varies depending on the host plant. We hypothesize that differences in the composition of the extracts lead to differences in antiviral activity. Some of the tested methanol extracts showed a pronounced inhibitory effect, both on replication and on extracellular virions, in relation to the ACV-resistant strain of HSV type 2 and SARS-CoV-2 in comparison with the other viral models used by us. The strongest antiviral effect was shown by the methanol extract of C. campestris with host Chenopodium spp. against SARS-CoV-2, as the virus inhibition was about 100%, and the virucidal effect showed a decrease in the viral titer by more than 2.5 lg. Based on the results obtained, we assume possible antagonistic interaction of individual metabolites in the total methanol extracts. Extract C3, applied at the maximum tolerable concentration and one level lower, inhibits SARS-CoV-2 about 100 percent. SARS-CoV-2-infected cells preserved mitochondrial activity and relatively preserved lysosomal activity; this is also the reason why the MTT test, as well as neutral red staining, is not applicable to this viral model propagated in the VERO E6 cell line.