Search Results (7)

Caprine herpesvirus 1 (CpHV-1) is responsible for significant economic losses in goat farming. The CpHV-1 genital infection in goats has been used as a homologous animal model for the study of human herpes simplex virus type 2 (HSV-2). This study aimed to investigate the in vitro virucidal and antiviral effect of lemon juice (LJ) and its main component, citric acid (CA), against CpHV-1 on Madin-Darby Bovine Kidney (MDBK) cells. Cytotoxicity was assessed using an XTT assay, while viral titers were determined by the Reed–Muench method and viral DNA was quantified via qPCR. Pure LJ (pH 2.3) and its corresponding CA solution demonstrated potent and rapid virucidal activity, reducing the viral titer by over 5.0 log10 TCID₅₀/50 µL within 1 min. When applied after viral entry, a non-cytotoxic dilution of LJ (pH 4.32) significantly inhibited viral replication, causing a 2.5 log10 TCID₅₀/50 µL reduction in viral titer and a corresponding decrease in viral DNA. The antiviral effects were minimal at a near-neutral pH of 6.67, probably interacting with envelope structures. These results suggest that LJ could be a potential low-cost topical agent or disinfectant for controlling CpHV-1 in goat populations and offer a basis for translational research on human herpesviruses. Full article

Background: Rift Valley fever virus (RVFV) is a significant mosquito-borne zoonotic virus with high public health and veterinary importance in Africa and the Middle East. Reliable diagnostic assays for detecting antibodies and assessing their functional neutralizing capacity are essential for surveillance programs, vaccine monitoring, and outbreak preparedness. Objective: This study evaluates and compares the analytical performance of a competitive enzyme-linked immunosorbent assay (cELISA) and a virus neutralization test (VNT) for detecting RVFV antibodies in vaccinated sheep sera, establishing an integrated laboratory workflow for virus titration, serological detection, and functional neutralization. Methods: Twenty serum samples were collected from sheep pre-vaccination and one month post-vaccination with Smithburn live attenuated RVFV vaccine. Sera were tested using a commercial multispecies RVFV competitive ELISA to detect antibodies specific to the viral nucleocapsid protein. Viral titration was conducted in Vero cells, and 50% tissue culture infective dose (TCID₅₀/0.1 mL) was calculated using the Reed and Muench method. VNT was performed at 24, 48, 72, and 96 h after infection with different viral doses (10² to 10⁵ TCID₅₀/0.1 mL), and the neutralizing ability of serial serum dilutions (1:2 to 1:1024) was tested. Compared with the control, protection was determined by cytopathic effect (CPE) inhibition. Results: ELISA revealed robust antibody signals up to a 1:32 dilution, with signal-to-noise (S/N) < 40%, whereas for higher dilutions, antibody detection became inconclusive or negative. Virus titration was performed to verify a stock concentration of 10^6.5 TCID₅₀/0.1 mL. The VNT exhibited time- and dose-dependent kinetics; high protection rates (≥97) were observed at 1:2–1:8 dilutions against 10²–10³ TCID₅₀/0.1 mL challenge doses; however, neutralizing efficacy decreased significantly at higher viral loads and higher serum dilutions. While cELISA and VNT results correlated strongly at low serum dilutions, the cELISA showed decreased sensitivity at dilutions ≥ 1:64, where the VNT remained capable of detecting functional neutralizing activity. Conclusions/Discussion: The results demonstrate that while both assays correlate well at high antibody concentrations, they diverge at lower concentrations. This discrepancy highlights the functional difference between binding antibodies (N-protein) and neutralizing antibodies (Gn/Gc glycoproteins). Consequently, the cELISA is ideal for rapid screening, whereas the VNT is indispensable for confirming functional immunity. Integrating both assays provides a more accurate immunological profile for RVFV surveillance and vaccine evaluation. Full article

Quantifying the infectious titre of preparations containing rabbit haemorrhagic disease virus (RHDV) is an essential virological technique during RHDV research. The infectious titre of an RHDV preparation is determined using a bioassay to identify the endpoint dilution at which 50% of rabbits become infected (RID₅₀). Previous publications have briefly described the method for estimating the infectious titre of RHDV preparations by challenging rabbits with 10-fold serial dilutions. However, these descriptions lack the critical considerations for a standardised method to estimate RID₅₀. These details are presented here, along with a comparison between the Reed–Muench, Dragstedt–Behrens, Spearman–Kärber, and probit regression methods for calculating the RID₅₀. All the statistical approaches demonstrated a high level of agreement in calculating the RID₅₀. To help assess the precision of the estimated infectious titre, the improved Spearman–Kärber and probit regression methods provide the 95% confidence intervals. The method outlined improves the accuracy of results when undertaking studies of pathogenicity, host resistance, and the production of vaccines against RHDV. Full article

The widespread use of zinc oxide nanoparticles (ZnO NPs) in multiple applications has increased the importance of safety considerations. ZnO NPs were synthesized, characterized, and evaluated for toxicity in Artemia salina and zebrafish (Danio rerio). NPs were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and ultraviolet-visible (UV-Vis) spectroscopy. The hydrodynamic size and stability of the ZnO NP surface were examined using a Zetasizer. Characterization techniques confirmed the ZnO wurtzite structure with a particle size of 32.2 ± 5.2 nm. Synthesized ZnO NPs were evaluated for acute toxicity in Artemia salina using the Probit and Reed and Muench methods to assess for lethal concentration at 50% (LC50). The LC50 was 86.95 ± 0.21 μg/mL in Artemia salina. Physical malformations were observed after 96 h at 50 μg/mL of exposure. The total protein and cytochrome P450 contents were determined. Further analysis was performed to assess the bioaccumulation capacity of zebrafish (Danio rerio) using ICP-OES. ZnO NP content in adult zebrafish was greater in the gastrointestinal tract than in the other tissues under study. The present analysis of ZnO NPs supports the use of Artemia salina and adult zebrafish as relevant models for assessing toxicity and bioaccumulation while considering absorption quantities. Full article

Sambucus nigra (SN) and Sambucus ebulus (SE) are widely used in folk medicine, primarily as antiviral agents for colds and influenza. In the current study, the antiviral activity of extracts of SN and SE fruits, flowers, and leaves were tested against herpes simplex virus type-2 (HSV-2). The HPLC analysis of the investigated extracts revealed the presence of phenolic acids, flavonoids, and anthocyanins. Rutin and chlorogenic acid were the main polyphenol constituents in flower and leaf extracts, whereas anthocyanins were predominant in fruit extracts. The flower extract of SN was characterized by the highest content of rutin and chlorogenic acid—14,232.1 mg/100 g dry weight (DW) and 7086.7 mg/100 g DW, respectively. SN fruit extract revealed the highest antioxidant activity measured using ORAC and HORAC methods—11,443.1 μmol TE/g and 8198.9 μmol GAE/g, respectively. To evaluate cytotoxicity, antiviral, and virucidal activities against HSV-2, the MTT assay and method of Reed and Muench were used. The least toxic extracts were PSNFrE and PSEFrE. The maximum tolerable concentration (MTC) of PSNFrE was 2000 μg/mL and the calculated CC₅₀ value for that extract was 3570 μg/mL. The inhibitory activity against virus replication was established for three of the extracts—PSNFlE, PSNLE, and PSNFrE. PSEFrE showed neither activity against virus replication, nor virucidal activity. The data suggest a significant inactivation of more than 98% after 60 min of contact of HSV-2 virions with the PSNFrE applied in MTC. The current study provides evidence that Sambucus nigra reveals anti-HSV-2 activity; however, the most active parts of the species were fruits. Therefore, SN fruits and their extracts can be used as an attendant therapy for HSV-2 viral infections. Full article

Global surveillance programs for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are showing the emergence of variants with mutations in the spike protein. Genomic and laboratory surveillance are important to determine if these variants may be more infectious or less susceptible to antiviral treatments and vaccine-induced antibodies. Three of the most predominant SARS-CoV-2 variants in Colombia during the epidemiological peaks of 2021 were isolated: Mu, a variant of interest; Gamma, a variant of concern; B.1.111, which lacks genetic markers associated with greater virulence. Microneutralization assays were performed by incubating 120 mean tissue culture infectious doses (TCID50) of each SARS-CoV-2 isolate with five two-fold serial dilutions of sera from 31 BNT162b2-vaccinated volunteers. The mean neutralization titer (MN50) was calculated by the Reed–Muench method. At the end of August, Mu represented 49% of coronavirus disease 2019 (COVID-19) cases in Colombia, followed by 25% of Gamma. In contrast, B.1.111 became almost undetectable. The evaluation of neutralizing antibodies suggests that patients vaccinated with BNT162b2 generate neutralizing antibody titers against the Mu variant at significantly lower concentrations relative to B.1.111 and Gamma. This study shows the importance of continuing surveillance programs of emerging variants, as well as the need to evaluate the neutralizing antibody response induced by other vaccines. Full article

Human noroviruses (HuNoVs) are the leading causative agents of epidemic and sporadic acute gastroenteritis that affect people of all ages worldwide. However, very few dose–response studies have been carried out to determine the median infectious dose of HuNoVs. In this study, we evaluated the median infectious dose (ID₅₀) and diarrhea dose (DD₅₀) of the GII.4/2003 variant of HuNoV (Cin-2) in the gnotobiotic pig model of HuNoV infection and disease. Using various mathematical approaches (Reed–Muench, Dragstedt–Behrens, Spearman–Karber, logistic regression, and exponential and approximate beta-Poisson dose–response models), we estimated the ID₅₀ and DD₅₀ to be between 2400–3400 RNA copies, and 21,000–38,000 RNA copies, respectively. Contemporary dose–response models offer greater flexibility and accuracy in estimating ID₅₀. In contrast to classical methods of endpoint estimation, dose–response modelling allows seamless analyses of data that may include inconsistent dilution factors between doses or numbers of subjects per dose group, or small numbers of subjects. Although this investigation is consistent with state-of-the-art ID₅₀ determinations and offers an advancement in clinical data analysis, it is important to underscore that such analyses remain confounded by pathogen aggregation. Regardless, challenging virus strain ID₅₀ determination is crucial for identifying the true infectiousness of HuNoVs and for the accurate evaluation of protective efficacies in pre-clinical studies of therapeutics, vaccines and other prophylactics using this reliable animal model. Full article