The coxsackie-adenovirus receptor (CAR) is used by reference strains and clinical isolates representing all six serotypes of coxsackievirus group B and by swine vesicular disease virus.
(65/2026)
Group B coxsackieviruses are etiologically linked to many human diseases, and cell surface receptors are postulated to play an important role in mediating their pathogenesis. The coxsackievirus adenovirus receptor (CAR) has been shown to function as a receptor for selected strains of coxsackievirus group B (CVB) serotypes 3, 4, and 5 and is postulated to serve as a receptor for all six serotypes. In this study, we demonstrate that CAR can serve as a receptor for laboratory reference strains and clinical isolates of all six CVB serotypes. Infection of CHO cells expressing human CAR results in a 1000-fold increase in CVB progeny virus titer compared to mock transfected cells. CAR was shown to be a functional receptor for swine vesicular disease virus (SVDV), as CHO-CAR cells but not CHO mock transfected controls were susceptible to SVDV infection, produced progeny SVDV, and developed cytopathic effects. Moreover, SVDV infection could be specifically blocked by monoclonal antibody to CAR (RmcB). SVDV infection of HeLa cells was also inhibited by an anti-CD55 MAb, suggesting that this virus, like some CVB, may interact with CD55 (decay accelerating factor) in addition to CAR. Finally, pretreatment of CVB or SVDV with soluble CAR effectively blocks virus infection of HeLa cell monolayers. (+info)
Competing death programs in poliovirus-infected cells: commitment switch in the middle of the infectious cycle.
(66/2026)
Productive poliovirus infection of HeLa cells leads to the canonical cytopathic effect (CPE), whereas certain types of abortive infection result in apoptosis. To define the time course of commitment to the different types of poliovirus-induced death, inhibitors of viral replication (guanidine HCl) or translation (cycloheximide) were added at different times postinfection (p.i.). Early in the infection (during the first approximately 2 h p.i.), predominantly proapoptotic viral function was expressed, rendering the cells committed to apoptosis, which developed several hours after viral expression was arrested. In the middle of infection, concomitantly with the onset of fast generation of viral progeny, the implementation of the viral apoptotic program was abruptly interrupted. In particular, activation of an Asp-Glu-Val-Asp (DEVD)-specific caspase(s) occurring in the apoptosis-committed cells was prevented by the ongoing productive infection. Simultaneously, the cells retaining normal or nearly normal morphology became committed to CPE, which eventually developed regardless of whether or not further viral expression was allowed to proceed. The implementation of the poliovirus-induced apoptotic program was suppressed in HeLa cells overexpressing the Bcl-2 protein, indicating that the fate of poliovirus-infected cells depends on the balance of host and viral pro- and antiapoptotic factors. (+info)
Isolation and characterization of a new subtype of Borna disease virus.
(67/2026)
Borna disease virus (BDV), the causative agent of severe meningoencephalitis in a wide variety of animal species, has been considered to be genetically invariable and to form a single type within the genus Bornavirus of the family Bornaviridae. BDV infections are of particular interest, because for the first time a virus infection appears to be linked to human psychiatric disorders. We now describe a new subtype of BDV isolated from a horse which was euthanatized due to severe, incurable neurological disease. The nucleotide sequence of this new strain, named No/98, differs from the reference strains by more than 15%, and the subtype is difficult to detect by standard reverse transcriptase PCR protocols. The nucleotide exchanges of the novel BDV isolate have surprisingly little effect on the primary structures of most viral proteins, with the notable exception of the X protein (p10), which is only 81% identical to its counterpart in reference strains. Our data indicate that the genome of BDV is far more variable than previously assumed and that naturally occurring subtypes may escape detection by currently used diagnostic assays. (+info)
Detection of astroviruses, enteroviruses, and adenovirus types 40 and 41 in surface waters collected and evaluated by the information collection rule and an integrated cell culture-nested PCR procedure.
(68/2026)
We evaluated the use of an integrated cell culture-reverse transcription-PCR (ICC-RT-PCR) procedure coupled with nested PCR to detect human astroviruses, enteroviruses, and adenovirus types 40 and 41 in surface water samples that were collected and evaluated by using the Information Collection Rule (ICR) method. The results obtained with the ICC-RT-PCR-nested PCR method were compared to the results obtained with the total culturable virus assay-most-probable-number (TCVA-MPN) method, the method recommended by the U.S. Environmental Protection Agency for monitoring viruses in surface and finished waters. Twenty-nine ICR surface water samples were analyzed. Viruses were concentrated by using filter adsorption-beef extract elution and organic flocculation techniques, and then the preparations were evaluated for viruses by visualizing cytopathic effects in the Buffalo green monkey kidney (BGMK) cell line. In the ICC-RT-PCR-nested PCR technique we used Caco-2 cells to propagate astroviruses and enteroviruses (ICC step), and we used BGMK cells to propagate adenovirus types 40 and 41, as well as enteroviruses. Fifteen of the 29 samples (51.7%) were positive for astrovirus as determined by the ICC-RT-PCR-nested PCR method, and eight of these samples (27.5%) contained infectious astrovirus. Seventeen of the 29 samples (58.6%) were positive for enteroviruses when the BGMK cell line was used, and six (27.6%) of these samples were determined to be infectious. Fourteen of the 29 samples (48.3%) were positive for adenovirus types 40 and 41, and 11 (37.9%) of these samples were determined to be infectious. Twenty-seven of the 29 samples (93.1%) were positive for a virus, and 19 (68.9%) of the samples were positive for an infectious virus. Only 5 of the 29 samples (17.2%) were positive as determined by the TCVA-MPN method. The ICC-RT-PCR-nested PCR method provided increased sensitivity compared to the TCVA-MPN method. (+info)
Rhinoviruses infect the lower airways.
(69/2026)
Rhinoviruses are the major cause of the common cold and a trigger of acute asthma exacerbations. Whether these exacerbations result from direct infection of the lower airway or from indirect mechanisms consequent on infection of the upper airway alone is currently unknown. Lower respiratory infection was investigated in vitro by exposing primary human bronchial epithelial cells to rhinoviruses and in vivo after experimental upper respiratory infection of human volunteers. Bronchial infection was confirmed by both approaches. Furthermore, rhinoviruses induced production of interleukin-6, -8, and -16 and RANTES and were cytotoxic to cultured respiratory epithelium. This evidence strongly supports a direct lower respiratory epithelial reaction as the initial event in the induction of rhinovirus-mediated asthma exacerbations. The frequency of infection and the nature of the inflammatory response observed are similar to those of the upper respiratory tract, suggesting that rhinovirus infections may be one of the most important causes of lower in addition to upper respiratory disease. (+info)
Comparison of infectious haematopoietic necrosis virus (IHNV) isolation on monolayers and in suspended cells.
(70/2026)
A cell culture virus isolation procedure for infectious haematopoietic necrosis virus (IHNV) in the epithelioma papulosum cyprini cell line (EPC) is described. Ovarian fluid samples were collected from fish and tested for IHNV at 9 farms. The samples were inoculated in parallel on 24 h old EPC cell monolayers and in freshly trypsinized cells. The titre of the initial virus isolation and of first passages were compared using the 2 methods for each sample. Titres were consistently higher in suspended cells and this method also proved more sensitive for isolation of IHN virus from ovarian fluids of infected fish. (+info)
Feline leukemia virus envelope sequences that affect T-cell tropism and syncytium formation are not part of known receptor-binding domains.
(71/2026)
The envelope protein is a primary pathogenic determinant for T-cell-tropic feline leukemia virus (FeLV) variants, the best studied of which is the immunodeficiency-inducing virus, 61C. We have previously demonstrated that T-cell-tropic, cytopathic, and syncytium-inducing viruses evolve in cats infected with a relatively avirulent, transmissible form of FeLV, 61E. The envelope gene of an 81T variant, which encoded scattered single-amino-acid changes throughout the envelope as well as a 4-amino-acid insertion in the C-terminal half of the surface unit (SU) of envelope, was sufficient to confer the T-cell-tropic, cytopathic phenotype (J. L. Rohn, M. S. Moser, S. R. Gwynn, D. N. Baldwin, and J. Overbaugh, J. Virol. 72:2686-2696, 1998). In the present study, we examined the role of the 4-amino-acid insertion in determining viral replication and tropism of FeLV-81T. The 4-amino-acid insertion was found to be functionally equivalent to a 6-amino-acid insertion at an identical location in the 61C variant. However, viruses expressing a chimeric 61E/81T SU, containing the insertion together with the N terminus of 61E SU, were found to be replication defective and were impaired in the processing of the envelope precursor into the functional SU and transmembrane (TM) proteins. In approximately 10% of cultured feline T cells (3201) transfected with the 61E/81T envelope chimeras and maintained over time, replication-competent tissue culture-adapted variants were isolated. Compensatory mutations in the SU of the tissue culture-adapted viruses were identified at positions 7 and 375, and each was shown to restore envelope protein processing when combined with the C-terminal 81T insertion. Unexpectedly, these viruses displayed different phenotypes in feline T cells: the virus with a change from glutamine to proline at position 7 acquired a T-cell-tropic, cytopathic phenotype, whereas the virus with a change from valine to leucine at position 375 had slower replication kinetics and caused no cytopathic effects. Given the differences in the replication properties of these viruses, it is noteworthy that the insertion as well as the two single-amino-acid changes all occur outside of predicted FeLV receptor-binding domains. (+info)
8-Difluoromethoxy-4-quinolone derivatives as anti-feline immunodeficiency virus (FIV) agents: important structural features for inhibitory activity of FIV replication.
(72/2026)
The inhibitory activities of various 8-difluoromethoxy-4-quinolone derivatives against feline immunodeficiency virus (FIV) replication in the chronically infected cell line P-CrFK were investigated. Certain derivatives were found to inhibit FIV production from P-CrFK cells in a dose-dependent manner without exhibiting cytotoxic effects at inhibitory concentrations. Based on this study, the structures important for anti-FIV activity are suggested to be (i) a carboxyl group at position C-3, and (ii) an aromatic modification at position 4 of the C-7 piperazinyl moiety. (+info)