In the present study, we evaluated the viability of non-enveloped viruses, minute virus of mice (MVM) and coxsackievirus B4 (CVB4), and enveloped-viruses, influenza A virus (H1N1) and herpes simplex virus type 1 (HSV-1), on surfaces. We also investigated the impact of the initial concentration of proteins and sodium chloride on the persistence of infectious CVB4 on surfaces. Viral suspensions (>104.5 TCID50) were applied to petri dish lids and dried under the air flow of a biosafety cabinet. The recovered viral preparations were titered on appropriate cell lines. Enveloped viruses persisted for less than 5 days while CVB4 and MVM persisted for weeks. However, repetitive cycles of drying and resuspension had a stronger virucidal effect on CVB4 than on H1N1 and HSV-1. These repetitive cycles had no effect on the infectious titer of MVM. When exposed to drying, the initial concentrations of bovine serum albumin (from 0 to 90 mg mL−1), fetal calf serum (from 0 to 100%), and sodium chloride (from 0 to 300 mg mL−1) affected the viability of CVB4. CVB4 was more likely to be inactivated by drying in a protein-rich medium, whereas the impact of drying was reduced in the presence of sodium chloride. The results of the present study demonstrated that the resistance of viruses to drying, as suggested by iterative drying, was not due to the heterogeneity of viral subpopulations, but was influenced by media compositions and component concentrations, as illustrated in the model of CVB4.

Theiler's virus and Mengo virus are representatives of the Cardiovirus genus within the picornavirus family. Their genome is an 8-kilobase long positive strand RNA molecule. This RNA molecule plays three roles in infected cells: It serves as a messenger RNA, acts as a template for genome replication, and is encapsidated to form progeny virions. We observed that a cis-acting signal required for replication of Theiler's virus was contained within a 130-nt stretch of the region encoding the capsid protein VP2. This RNA sequence does not inf luence internal ribosome entry site-mediated translation initiation and thus likely acts directly as a signal for the replication complex. We found a similar signal in the VP2-coding sequence of Mengo virus, and both signals could be functionally exchanged. Within the replication element, a 9-nt sequence that is highly conserved among cardioviruses was shown to be essential for replication. This conserved sequence was contained in mostly unpaired regions of the RNA secondary structure predicted for the replication elements of the various cardioviruses. Interestingly, a similar replication element has been reported to occur in the distantly related human rhinovirus type 14, suggesting that such elements could be conserved throughout the picornavirus family. However, the different location of the replication elements in rhinovirus and cardioviruses, and the fact that they were not functionally exchangeable, is raising intriguing questions about the evolution of such signals in picornaviruses.

BACKGROUND: Myxoma resistance protein 1 (MxA) is induced during viral infections. MxA testing could be helpful to differentiate between viral and bacterial infections.

Coxsackievirus B4 (CVB4)-induced production of alpha interferon (IFN-␣) by peripheral blood mononuclear cells (PBMC) is enhanced in vitro by nonneutralizing anti-CVB4antibodies from healthy subjects and, to a higher extent, from patients with insulin-dependent diabetes mellitus. In this study, we focused on identification of the viral target of these antibodies in CVB systems. High levels of IFN-␣ were obtained in supernatants of PBMC incubated with CVB4E2 or CVB3 and plasma from healthy subjects and, to a higher extent, from patients. The VP4 capsid proteins dissociated by heating at 56°C from CVB4E2 (VP4 CVB4 ) and CVB3 (VP4 CVB3 ) but not H antigen preincubated with plasma from healthy subjects or patients inhibited the plasma-dependent enhancement of CVB4E2-and CVB3-induced IFN-␣ synthesis. There was no cross-reaction between VP4 CVB4 and VP4 CVB3 in the inhibiting effect. IFN-␣ levels in culture supernatants showed dosedependent correlation with anti-VP4 antibodies eluted from plasma specimens using VP4-coated plates. There were higher index values for anti-VP4 antibodies detected by enzyme-linked immunosorbent assay (ELISA) and higher proportions of positive detection in 40 patients than in 40 healthy subjects (80% versus 15% for anti-VP4 CVB4 ). There was no relationship between the levels of anti-CVB neutralizing antibodies and the detection of anti-VP4 antibodies by ELISA. The CVB plasma-induced IFN-␣ levels obtained in PBMC cultures in the anti-VP4 antibody-positive groups were significantly higher than those obtained in the anti-VP4 antibody-negative groups regardless of the titers of anti-CVB neutralizing antibodies. These results show that VP4 is the target of antibodies involved in the plasma-dependent enhancement of CVB4E2-and CVB3-induced IFN-␣ synthesis by PBMC.