The specificity of Helicoverpa armigera stunt virus infectivity.

Helicoverpa armigera stunt virus (HaSV) is a member of the Tetraviridae family of RNA viruses whose replication and expression strategies are not well understood due to the absence of an in vitro cell culture system. We set out to find such a system for HaSV by screening an array of 13 insect and 1 mammalian cell culture lines with both virus particle infection and genomic RNA transfection. No cell line was found to be permissive for replication, although entry of genomic RNA was verified. The apparent specificity of this virus for its in vivo midgut target site was strongly corroborated by studies involving Northern blots of RNA extracted from infected insects. Only larval midgut RNA showed the presence of virus after hosts were infected per os or by injection which exposed other host cell types to the virus. The absence of replication in cell culture was due to a lack, or presence, of host factors important to replicase activity and also the likely absence of virus particle binding and entry. We thus provide both in vitro- and in vivo-based evidence demonstrating that this virus is extremely specific in the type of cells in which it will initiate an infection.     

The suppression of one plant virus by another

Severe etch virus prevents die multiplication of potato virus Y and Hyoscyamus virus 3 and replaces them even in plants in which they are established. Mild etch virus reduces the concentration of potato virus Y but does not suppress it completely. Cucumber virus 1 multiplies normally in mixed infections with any of the three other insect-transmitted viruses. Possible implications of these results on the mechanism of virus multiplication are discussed; it is suggested that these viruses inactivate in cell sap at approximately the same rate as they denature in vitro.
No differences were found between the stability of antibodies to viruses with different properties.     

Spontaneous resolution of severe chronic glue ear in children and the effect of adenoidectomy,tonsillectomy, and insertion of ventilation tubes (grommets).

OBJECTIVE--To measure the time to spontaneous resolution of severe chronic otitis media with effusion (glue ear) in children and study the effects of adenoidectomy, adenotonsillectomy, and ventilation tubes (grommets). DESIGN--Randomised controlled study over 12 years. SETTING--Paediatric otorhinolaryngology clinics and in-patient unit. SUBJECTS--228 children aged 2-9 years with pronounced hearing loss from glue ear and persistent bilateral middle ear effusions confirmed on three occasions over three months. INTERVENTIONS--Children were randomly allocated to adenotonsillectomy, adenoidectomy, or neither procedure. In all groups a Shepard type ventilation tube was inserted in one randomly chosen ear. Follow up was annually for five years and then less often for up to seven years four months. For analysis the two operated groups were combined. MAIN OUTCOME MEASURES--Otoscopic clearance of fluid, change in tympanogram, and improvement in mean audiometric hearing threshold. RESULTS--Survival analysis showed appreciable otoscopic and tympanometric resolution of fluid with ventilation tubes alone and adenoidectomy alone compared with no surgery. Further improvement was seen after combination of both treatments. Mean audiometric hearing thresholds improved with fluid resolution. Resolution was delayed in younger children and in those whose parents smoked, irrespective of treatment. Whereas a single insertion of a Shepard tube resolved the glue for a mean (SD) period of 9.5 (5.2) months, the effect of adenoidectomy was sustained throughout follow up. CONCLUSIONS--Treatment of glue ear considerably shortened the time to fluid resolution, combined adenoidectomy and tube insertion being better than either procedure alone. Resolution was longer in younger children and those whose parent(s) smoked, irrespective of treatment.     

alpha-L-iduronidase premature stop codons and potential read-through in mucopolysaccharidosis type I patients

alpha-L-Iduronidase is a glycosyl hydrolase involved in the sequential degradation of the glycosaminoglycans heparan sulphate and dermatan sulphate. A deficiency in alpha-L-iduronidase results in the lysosomal accumulation and urinary secretion of partially degraded glycosaminoglycans and is the cause of the lysosomal storage disorder mucopolysaccharidosis type I (MPS I; Hurler and Scheie syndromes; McKusick 25280). The premature stop codons Q70X and W402X are two of the most common alpha-l-iduronidase gene (IDUA) mutations accounting for up to 70% of MPS I disease alleles in some populations. Here, we have reported a new mutation, making a total of 15 different mutations that can cause premature IDUA stop codons and have investigated the biochemistry of these mutations. Natural stop codon read-through was dependent on the fidelity of the codon when evaluated at Q70X and W402X in CHO-K1 cells, but the three possible stop codons TAA, TAG and TGA, had different effects on mRNA stability and this effect was context dependent. In CHO-K1 cells expressing the Q70X and W402X mutations, the level of gentamicin-enhanced stop codon read-through was slightly less than the increment in activity caused by a lower fidelity stop codon. In this system, gentamicin had more effect on read-through for the TAA and TGA stop codons when compared to the TAG stop codon. In an MPS I patient study, premature TGA stop codons were associated with a slightly attenuated clinical phenotype, when compared to classical Hurler syndrome (e.g. W402X/W402X and Q70X/Q70X genotypes with TAG stop codons). Natural read-through of premature stop codons is a potential explanation for variable clinical phenotype in MPS I patients. Enhanced stop codon read-through is a potential treatment strategy for a large sub-group of MPS I patients.