Foot-and-mouth disease virus (FMDV) as with other RNA viruses recruits various

Foot-and-mouth disease virus (FMDV) as with other RNA viruses recruits various host cell factors to assist in the translation and replication of the virus genome. antibody that recognizes only the nonmethylated form of RHA. In contrast to alterations in the subcellular distribution of nuclear factors observed during infection with the related cardioviruses cytoplasmic accumulation of RHA did not require the activity of the FMDV leader protein. Using IFM we have found cytoplasmic RHA in proximity to the viral 2C and 3A proteins which promotes the assembly of the replication complexes as well as cellular poly(A) binding protein (PABP). Coimmunoprecipitation assays confirmed that these proteins are complexed with RHA. We have also identified a novel interaction between RHA and the S fragment in the FMDV 5′ para-iodoHoechst 33258 nontranslated region. Moreover a reduction in the expression of RHA using RHA-specific small interfering RNA constructs inhibited FMDV replication. These results indicate that RHA plays an essential role in the replication of FMDV and potentially other picornaviruses through ribonucleoprotein complex formation at the 5′ end of the genome and by interactions with 2C 3 and Rabbit polyclonal to AKR1A1. PABP. Foot-and-mouth disease virus (FMDV) is a highly contagious viral pathogen of cloven-hoofed animals (22). Infection can occur through direct para-iodoHoechst 33258 contact with infected animals or indirectly by aerosol transmission with symptoms appearing 2 to 3 3 days postexposure. Outbreaks of FMDV among livestock of disease-free nations have had extremely deleterious effects on the economies of those countries since international trade of animals and animal products from countries experiencing an FMD outbreak is strictly forbidden (22 34 48 Indeed several economically devastating outbreaks have occurred over the past decade on almost every continent. A chemically inactivated whole-virus vaccine has been used to contain the disease but it is slow acting and does not permit distinction between infected and vaccinated animals (7 para-iodoHoechst 33258 8 21 40 FMDV is a prototypic member of the genus of the family (15 39 The infectious virion is a nonenveloped icosahedron composed of four structural proteins (VP1 to VP4) which surrounds a positive-sense single-stranded RNA genome. The genome encodes a single open reading frame which is translated into a large polyprotein that is subsequently cleaved to produce 14 mature virus proteins by three virus proteases (Lpro 2 and 3Cpro) (9). The virus translation products include the four structural proteins and 10 nonstructural para-iodoHoechst 33258 proteins (NSPs) (Lpro 2 2 2 3 3 to 3B3 3 and 3Dpol). During viral para-iodoHoechst 33258 replication the genomic RNA not only directs the synthesis of the viral polyprotein but also serves as template for RNA synthesis. Studies of other picornaviruses including poliovirus have revealed that the processes of translation and RNA replication cannot occur simultaneously on the same RNA molecule (42 55 Therefore a molecular switch must exist that shuts down translation thus allowing for the initiation of RNA replication. It has been demonstrated in the context of flaviviruses that the circularization of the single-stranded positive-sense RNA genome through an interaction of the 5′ and 3′ nontranslated regions (NTRs) halts translation and allows for initiation of RNA replication (1-3 31 54 In the case of poliovirus the bridge between the NTRs appears to be mediated by interactions of cellular and virus factors bound to the respective NTRs specifically para-iodoHoechst 33258 the virus-encoded 3CD precursor and the cellular poly(C) binding protein (PCBP2) and poly(A) binding protein (PABP) (4 19 Recently the 5′ and 3′ NTRs of FMDV were shown to physically interact in vitro in the absence of cellular or viral protein. When mixed with cellular extracts different portions of the NTRs coprecipitated four different proteins migrating at 120 70 45 and 30/34 kDa (49). The identities of p45 and p70 were confirmed to be PCBP2 and PABP respectively. However the identity and role in the virus life cycle of the p120 and p30/34 proteins remain unknown. RNA helicase A (RHA) with an approximate molecular mass of 130 kDa was first reported to unwind double-stranded DNA and was later found to have higher affinity for double-stranded RNA (59-62). RHA also known as DHX9 and NDHII possesses two double-stranded RNA binding domains at the N terminus with a classical DEAD box/helicase domain in the center and the extreme C terminus.