Search Results (3)

Hepatitis A virus (HAV), a major cause of acute liver infections, is transmitted through the fecal–oral route and close contact with infected individuals. Current HAV standardized methods rely on the detection of virus antigen or RNA, which do not differentiate between infectious and non-infectious HAV. The objective of this study was to develop a prototype cell-based electrochemical biosensor for detection of infectious HAV. A cell culture-adapted HAV strain (HM175/18f) and its permissive cells (FRhK-4), along with gold nanoparticle-modified screen-printed electrodes, were used to develop the biosensor. Electrochemical impedance spectroscopy was used to quantify the electrical impedance signal. Nyquist plots showed successful fabrication of the cell-based biosensor. The optimum period of HAV incubation with the biosensor was 6 h. A significant linear relationship (R² = 0.98) was found between the signal and a 6-log range of HAV titers, with a limit of detection of ~5 TCID₅₀/mL (tissue culture infectious dose). The biosensor did not detect non-target viruses such as feline calicivirus and human coronavirus 229E. The biosensor was stable for 3 to 7 days at an abusive temperature (37 °C), retaining ~90 to 60% of the original signal, respectively. In conclusion, this prototype cell-based biosensor is capable of rapidly detecting low levels of infectious HAV. Full article

African green monkey (AGM) spumaretroviruses have been less well-studied than other simian foamy viruses (SFVs). We report the biological and genomic characterization of SFVcae_FV2014, which was the first foamy virus isolated from an African green monkey (AGM) and was found to be serotype 3. Infectivity studies in various cell lines from different species (mouse, dog, rhesus monkey, AGM, and human) indicated that like other SFVs, SFVcae_FV2014 had broad species and cell tropism, and in vitro cell culture infection resulted in cytopathic effect (CPE). In Mus dunni (a wild mouse fibroblast cell line), MDCK (Madin-Darby canine kidney cell line), FRhK-4 (a fetal rhesus kidney cell line), and MRC-5 (a human fetal lung cell line), SFVcae_FV2014 infection was productive resulting in CPE, and had delayed or similar replication kinetics compared with SFVmcy_FV21 and SFVmcy_FV34[RF], which are two Taiwanese macaque isolates, designated as serotypes 1 and 2, respectively. However, in Vero (AGM kidney cell line) and A549 (a human lung carcinoma cell line), the replication kinetics of SFVcae_FV2014 and the SFVmcy viruses were discordant: In Vero, SFVcae_FV2014 showed rapid replication kinetics and extensive CPE, and a persistent infection was seen in A549, with delayed, low CPE, which did not progress even upon extended culture (day 55). Nucleotide sequence analysis of the assembled SFVcae_FV2014 genome, obtained by high-throughput sequencing, indicated an overall 80–90% nucleotide sequence identity with SFVcae_LK3, the only available full-length genome sequence of an AGM SFV, and was distinct phylogenetically from other AGM spumaretroviruses, corroborating previous results based on analysis of partial env sequences. Our study confirmed that SFVcae_FV2014 and SFVcae_LK3 are genetically distinct AGM foamy virus (FV) isolates. Furthermore, comparative infectivity studies of SFVcae_FV2014 and SFVmcy isolates showed that although SFVs have a wide host range and cell tropism, regulation of virus replication is complex and depends on the virus strain and cell-specific factors. Full article

The accurate virus detection, strain discrimination, and source attribution of contaminated food items remains a persistent challenge because of the high mutation rates anticipated to occur in foodborne RNA viruses, such as hepatitis A virus (HAV). This has led to predictions of the existence of more than one sequence variant between the hosts (inter-host) or within an individual host (intra-host). However, there have been no reports of intra-host variants from an infected single individual, and little is known about the accuracy of the single nucleotide variations (SNVs) calling with various methods. In this study, the presence and identity of viral SNVs, either between HAV clinical specimens or among a series of samples derived from HAV clone1-infected FRhK4 cells, were determined following analyses of nucleotide sequences generated using next-generation sequencing (NGS) and pyrosequencing methods. The results demonstrate the co-existence of inter- and intra-host variants both in the clinical specimens and the cultured samples. The discovery and confirmation of multi-viral RNAs in an infected individual is dependent on the strain discrimination at the SNV level, and critical for successful outbreak traceback and source attribution investigations. The detection of SNVs in a time series of HAV infected FRhK4 cells improved our understanding on the mutation dynamics determined probably by different selective pressures. Additionally, it demonstrated that NGS could potentially provide a valuable investigative approach toward SNV detection and identification for other RNA viruses. Full article