Rhinoviruses cause serious morbidity and mortality as the major etiological agents of asthma exacerbations and the common cold. A major obstacle to understanding disease pathogenesis and to the development of effective therapies has been the lack of a small-animal model for rhinovirus infection. Of the 100 known rhinovirus serotypes, 90% (the major group) use human intercellular adhesion molecule-1 (ICAM-1) as their cellular receptor and do not bind mouse ICAM-1; the remaining 10% (the minor group) use a member of the low-density lipoprotein receptor family and can bind the mouse counterpart. Here we describe three novel mouse models of rhinovirus infection: minor-group rhinovirus infection of BALB/c mice, major-group rhinovirus infection of transgenic BALB/c mice expressing a mouse-human ICAM-1 chimera and rhinovirus-induced exacerbation of allergic airway inflammation. These models have features similar to those observed in rhinovirus infection in humans, including augmentation of allergic airway inflammation, and will be useful in the development of future therapies for colds and asthma exacerbations.

The replication of poliovirus, a positive-stranded RNA virus, requires translation of the infecting genome followed by virus-encoded VPg and 3D polymerase-primed synthesis of a negative-stranded template. RNA sequences involved in the latter process are poorly defined. Since many sequences involved in picornavirus replication form RNA structures, we searched the genome, other than the untranslated regions, for predicted local secondary structural elements and identified a 61-nucleotide (nt) stem-loop in the region encoding the 2C protein. Covariance analysis suggested the structure was well conserved in the Enterovirus genus of the Picornaviridae. Site-directed mutagenesis, disrupting the structure without affecting the 2C product, destroyed genome viability and suggested that the structure was required in the positive sense for function. Recovery of revertant viruses suggested that integrity of the structure was critical for function, and analysis of replication demonstrated that nonviable mutants did not synthesize negative strands. Our conclusion, that this RNA secondary structure constitutes a novel poliovirus cis-acting replication element (CRE), is supported by the demonstration that subgenomic replicons bearing lethal mutations in the native structure can be Poliovirus, the archetypal picornavirus, is arguably one of the best characterized of all viruses. The availability of infectious molecular clones (33) has enabled the application of reverse genetics to understand the function of the nonstructural proteins and the noncoding regions (NCR) of the virus genome (reviewed in reference 41). The 7.4-kb single-stranded positive (messenger)-sense RNA genome encodes a single polyprotein and contains the necessary signals for virus replication in the cell cytoplasm. Posttranslational cleavage of the polyprotein by virus-encoded proteases (2A pro and 3C pro ) yields the four capsid proteins (VP1 to VP4), the RNA-dependent RNA polymerase (3D pol ), and the accessory proteins required for replication. The input RNA acts as a template for the synthesis of a negative strand which, in turn, is used as a template for synthesis of genome sense RNA. The virus-encoded protein VPg (3A) is implicated as a protein primer for both positive-and negative-sense strand initiation, as are RNA sequences occupying the 5Ј NCR of the virus genome. A cloverleaf (CL) structure of 88 nucleotides (nt) at the 5Ј end of the genome interacts with the virus 3C pro D pol and either the VPg-containing precursor 3AB or the cellular poly-C binding protein type 2 (PCBP2) (2,3,11,28). This 5Ј NCR ribonucleoprotein complex is required for replication and may also be involved in the suppression of virus translation (10).RNA sequences and structures within the 3Ј NCR presumed to be involved in replication are much less well defined. Chimeric polioviruses in which the 3Ј NCR is replaced by the analogous region of other picornaviruses generally retain viability (35), even though there is little sequence or structural homology between substituted 3Ј NCR....

SUMMARYThe antigenic sites recognized by monoclonal antibodies with neutralizing activity for the Sabin vaccine strains of poliovirus of serotypes 1, 2 and 3 have been studied by the isolation and characterization of mutants resistant to neutralization by antibody. Three distinct sites have been identified which are designated site 1, site 2 and site 3. Site 1 includes a region of 12 amino acids of VP1, from residues 89 to 100, and a corresponding region of VP1 has been identified as an antigenic site for poliovirus 2. This site was strongly immunodominant in type 2 and type 3 but was not detected for poliovirus 1. Site 2 is a complex site including residues 220 to 222 from VP1 (site 2a) with residues including 169 and 170 and others of VP2 (site 2b). Both site 2a and site 2b have been detected in type 1 poliovirus, while as yet only site 2b has been detected in type 3 poliovirus. Site 3 is a complex site including residues 286 to 290 from VP1 (site 3a) with residues including 58 and 59 and others of VP3 (site 3b). Both sites 3a and 3b have been detected in type 3 poliovirus, while as yet only site 3b has been detected in type 1 poliovirus. INTRODUCTIONPoliovirus is a picornavirus of the enterovirus genus occurring in three distinct serotypes. The virion consists of a single strand of messenger-sense RNA enclosed in a capsid made up of 60 copies of each of the four structural proteins VP1, VP2, VP3 and VP4. Nucleotide sequences of the genomic RNA of several strains of poliovirus have been published (Kitamura et al., 1981 ;Toyoda et al., 1984;Cann et al., 1984) and the X-ray crystallographic structure of the Mahoney strain of type 1 poliovirus has been solved to 2.9 A (0-29 nm) resolution .

The rapidly increasing incidence of type 1 diabetes implies that environmental factors are involved in the pathogenesis. Enteroviruses are among the suspected environmental triggers of the disease, and the interest in exploring the possibilities to develop vaccines against these viruses has increased. Our objective was to identify enterovirus serotypes that could be involved in the initiation of the disease process by screening neutralizing antibodies against 41 different enterovirus types in a unique longitudinal sample series from a large prospective birth-cohort study. The study participants comprised 183 case children testing persistently positive for at least two diabetes-predictive autoantibodies and 366 autoantibody-negative matched control children. Coxsackievirus B1 was associated with an increased risk of β-cell autoimmunity. This risk was strongest when infection occurred a few months before autoantibodies appeared and was attenuated by the presence of maternal antibodies against the virus. Two other coxsackieviruses, B3 and B6, were associated with a reduced risk, with an interaction pattern, suggesting immunological cross-protection against coxsackievirus B1. These results support previous observations suggesting that the group B coxsackieviruses are associated with the risk of type 1 diabetes. The clustering of the risk and protective viruses to this narrow phylogenetic lineage supports the biological plausibility of this phenomenon.

Most of the small number of cases of poliomyelitis which occur in countries where Sabin's attenuated poliovirus vaccines are used are temporally associated with administration of vaccine and involve polioviruses of types 2 and 3 (ref. 1). Recent studies have provided convincing evidence that the Sabin type 2 and 3 viruses themselves may revert to a neurovirulent phenotype on passage in man. We report here that a point mutation in the 5' noncoding region of the genome of the poliovirus type 3 vaccine consistently reverts to wild type in strains isolated from cases of vaccine-associated poliomyelitis. Virus with this change is rapidly selected on passage through the human gastrointestinal tract. The change is associated with a demonstrable increase in the neurovirulence of the virus.