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SNPs in innate immune genes are important in determining susceptibility to RSV bronchiolitis.

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The association of variants of genes encoding interleukin (IL)-4 and the IL-4 receptor alpha chain (IL-4Ralpha) with respiratory syncytial virus (RSV) bronchiolitis was examined in hospitalized infants. Polymorphisms in IL-4 (C-590T) and IL-4Ralpha (I50V and Q551R) were genotyped by restriction fragment-length polymorphism analysis. Control subjects included parents of the hospitalized children (for the transmission/disequilibrium test), and a random population sample (for the case-control study). Results were also analyzed in a combination of these 2 tests, using Fisher's method. The IL-4 590T allele was found more frequently among children hospitalized with RSV than expected in the case-control (odds ratio [OR], 1.43; P=.04) and combination (OR, 1.41; P=.02) tests. Among children who were >6 months old when they were hospitalized, compared with the control group or with the <6 months old who were hospitalized for RSV infection, higher frequencies of both the IL-4 590T allele and the IL-4Ralpha R551 allele were found. These results indicate that gain-of-function variants of T helper type 2 cytokine genes may play a role in increasing the severity of RSV disease, which appears more pronounced after the first half-year of life.

We examined the influence of inactivation of various genes located in the unique short (Us) region of pseudorabies virus on virus replication and assembly in porcine nasal mucosa explant cultures. The following strains were used: the virulent wild-type strain NIA-3, and strains derived from NIA-3 containing a mutation inactivating the genes encoding either the US3-encoded protein kinase (PK), gG, gD, gI, gE, the 28 kDa (' 28K') protein (single mutant), or the 28K and 11 kDa ('11K') proteins (double mutant). In addition a wild-type rescuant was used, which was generated by marker rescue from a PK mutant. All virus strains infected nasal epithelium and had invaded the stroma after approximately 24 h. The morphogenesis in nasal epithelium cells of two PK-mutants showed the most striking differences compared to the parent NIA-3 strain and the other mutant strains. The changes could be ascribed to the US3-encoded PK because the rescue mutant showed a similar morphogenesis to wild-type NIA-3. The transmembrane transport of the PKmutants was impaired at the outer nuclear membrane which resulted in an accumulation of virions in the perinuclear space. These results suggest that proteins, phosphorylated by the US3-encoded PK, are involved in debudding of virus particles at the outer nuclear membrane. This defect in the transport of the US3 mutant probably explains their reduced replication in vitro. The gG-, gD , gI , gEL 28K-and 11K-mutant strains showed minor or no changes in viral assembly. Thus the reported decreased virulence of the gD , gF and gE mutants was, in contrast to that of the PKmutants, not associated with clear alterations in morphogenesis.