Dual Stem Loops within the Poliovirus Internal Ribosomal Entry Site Control Neurovirulence

Abstract

In the human central nervous system, susceptibility to poliovirus (PV) infection is largely confined to a specific subpopulation of neuronal cells. PV tropism is likely to be determined by cell-external components such as the PV receptor CD155, as well as cell-internal constraints such as the availability of a suitable microenvironment for virus propagation. We reported previously that the exchange of the cognate internal ribosomal entry site (IRES) within the 5′ nontranslated region of PV with its counterpart from human rhinovirus type 2 (HRV2) can eliminate the neuropathogenic phenotype in a transgenic mouse model for poliomyelitis without diminishing the growth properties in HeLa cells. We now show that attenuation of neurovirulence of PV/HRV2 chimeras is not confined to CD155 transgenic mice but is evident also after intraspinal inoculation intoCynomolgus monkeys. We have dissected the PV and HRV2 IRES elements to determine those structures responsible for neurovirulence (or attenuation) of these chimeric viruses. We report that two adjacent stem loop structures within the IRES cooperatively determine neuropathogenicity.

Growth phenotypes and biosafety profiles in poliovirus‐receptor transgenic mice of recombinant oncolytic polio/human rhinoviruses

“…The replacement of the entire PV IRES with that of HRV2 produces a much more pronounced reduction of neuronal propagation when tested in human cells of neuronal derivation (e.g. SK-N-MC neuroblastoma cells [Gromeier et al, 1996[Gromeier et al, , 1999) or HEK-293 cells [Campbell et al, 2005] or in CD155 tg mice [Gromeier et al, 1996]. At the same time, highly attenuated PV/HRV2 chimeras [PV1(RIPO), PV1(RIPOS), and PVS(RIPO)] exhibit strong oncolytic activity for primary and metastatic CNS tumor cells [Gromeier et al, 2000;Merrill et al, 2004;Ochiai et al, 2004Ochiai et al, , 2006.…”

Enterovirus infections of the central nervous system

“…Attenuation of EVs through mutations in the genome has historically led to efficient vaccine production. Perhaps the most well-known attenuated form of PV is that used for the Sabin vaccine, which has decreased neurovirulence in part controlled by two stem loops in the viral IRES (Gromeier et al, 1999). Another mutation that can cause CNS attenuation is located between the 5′ NTR cloverleaf and IRES and reduces the binding of polypyrimidine tract-binding protein (Guest et al, 2004).…”

Experimental hepatitis A virus (HAV) infection in cynomolgus monkeys (Macaca fascicularis): evidence of active extrahepatic site of HAV replication

“…Like other members of the Picornavirus family, HAV replication is via a complementary minus-strand RNA (intermediate replicative). The copies of picornavirus minus-strands are 100-fold fewer than that of plus-strands in infected cells, suggesting that each minus-strand may serve as a template for the synthesis of many plus-strands (Gromeier et al 1999;de Paula et al 2009). The presence of HAV RNA is not sufficient to demonstrate its replication in other tissues, as viral RNA may be present because of contamination with plasma and ⁄ or adherence of circulating viruses, or as a result of immune complexes of the virus with secretory immunoglobulin.…”