Age-Dependent Poliovirus Replication in the Mouse Central Nervous System Is Determined by Internal Ribosome Entry Site-Mediated Translation

Abstract

Mouse cells are not permissive for the replication of human rhinovirus type 2 (HRV2). To determine the role of the HRV2 internal ribosome entry site (IRES) in determining species specificity, a recombinant poliovirus (P1/HRV2) was constructed by substituting the poliovirus IRES with the IRES from HRV2. This recombinant virus replicated in all human and murine cell lines examined, demonstrating that the HRV2 IRES does not limit viral replication in transformed murine cells. P1/HRV2 replicated in the brain and spinal cord in neonatal but not adult mice transgenic for the poliovirus receptor, CD155. Passage of P1/HRV2 in mice led to selection of a virus that caused paralysis in neonatal mice. To determine the relationship between HRV2 IRES-mediated translation and replication of P1/HRV2 in mice, recombinant human adenoviruses were used to express bicistronic mRNAs in murine organs. The results demonstrate that the HRV2 IRES mediates translation in organs of neonatal but not adult mice. These findings show that HRV2 IRES-mediated translation is a determinant of virus replication in the murine brain and spinal cord and suggest that the IRES determines the species specificity of HRV2 infection.Human rhinoviruses (HRVs) are nonenveloped, positivestranded RNA viruses of the family Picornaviridae (8). Approximately 100 HRV serotypes have been identified and divided into two groups based on receptor usage. The receptor for major group HRVs is human intracellular adhesion molecule 1 (hICAM-1), and the receptor for minor group HRVs is human low-density lipoprotein receptor (8). HRVs replicate in the epithelium of the human respiratory tract (1, 2, 11, 41) and are responsible for the majority of common cold infections of humans (36). Only humans develop clinical symptoms after HRV infection; experimental asymptomatic infections have been documented in chimpanzees (10) and gibbons (35). A rodent model for infection with wild-type HRV has not been identified (22).A small-animal model of HRV infection would be useful for elucidating the mechanisms of HRV-induced pathogenesis and to develop therapeutic interventions. The limited host range of most HRV serotypes (8) has hindered establishment of such a model. Mouse cells are not permissive for the replication of minor group serotypes, despite the ability of these viruses to enter these cells after binding the murine homolog of human low-density lipoprotein receptor. Two exceptions are HRV1A (37) and a variant of HRV2 (HRV2/L) selected by passage in mouse cells (43). The changes required for growth of HRV2/L in mouse cells have not been identified (43). HRV2/L produces altered P2 proteins in infected cells, suggesting that the block to HRV2 replication in murine cells could be due to a defect in RNA replication (29). This conclusion is supported by the finding that HRV2/L is less sensitive than HRV2 to chemical inhibitors of RNA replication (43). It is believed that mouse cell lines are neither permissive nor susceptible to infection with most major group HRVs. While the block to ...

A Host-Specific, Temperature-Sensitive Translation Defect Determines the Attenuation Phenotype of a Human Rhinovirus/Poliovirus Chimera, PV1(RIPO)

“…After replacing the IRES of PV1(M) with that of coxsackie virus B or hepatitis C virus or the Sabin virus type 3 PV, however, Kauder and colleagues (26) originally concluded that the tropism of wildtype and vaccine strains of poliovirus is determined in a step after IRES-mediated translation. Using a different experimental strategy, they subsequently suggested that IRES-derived translation plays an important role in neurovirulence of a chimeric virus (P1/HRV2) that is nearly identical to PV1(RIPO) (25).…”

“…Although these elements are distinct in structure, they are interchangeable between viruses of different genera and even of different families, yielding novel, viable chimeric viruses, some of which have interesting phenotypes (1,9,15,18,35). Several studies with IRES-chimeric viruses illustrated the potential contribution of IRES elements toward cell tropism of the virus (9,15,25), although tropism is, in fact, governed by a multitude of different determinants. These include (i) an incompatibility of viral proteins with viral proliferation in different hosts.…”

Modification of the Untranslated Regions of Human Enterovirus 71 Impairs Growth in a Cell-Specific Manner

“…The HEV71 5= UTR contains a type I IRES, which is common to all members of the enterovirus genus (34). The primary roles of the cloverleaf and IRES are in the control of replication and translation, respectively (18,20,22,24). However, they have been shown to be multifunctional elements with overlapping roles (4,16,21,32,40).…”

Attenuation of Rabies Virus Replication and Virulence by Picornavirus Internal Ribosome Entry Site Elements

“…The deficiency of young mice to combat infection is predominantly attributed to the immature status of the adaptive immune system, but a deficient innate immune response has also been observed (17), which may explain the need for IFN feedback for protection against SAD HRV2-P. Age-dependent attenuation in mice has also been observed for picornaviruses (30,51). It remains to be determined whether this relates to the maturation of the immune system or to differences in IRES activities.…”

“…Particularly in HEK 293 cells, which are of neuronal origin (50), and in which chimeric PV containing the HRV2 IRES are severely attenuated (10), a quite high translational activity of the HRV2 IRES was observed. While general organ-or species-specific preferences (30,31) were not observed for either IRES, it will be interesting to determine the reason for the striking differences between PV and HRV2 IRES in individual cell lines, such as HepG2.…”