Assessment of the ferret as an in vivo model for mumps virus infection.

Humans are the sole reservoir for mumps virus (MuV), the causative agent of mumps. No animal model currently exists; therefore, in vivo knowledge of the virus is limited. Ferrets were assessed for their susceptibility to MuV based on their success as a model for influenza. We infected ferrets with clinical or attenuated vaccine MuVs by the nasal route and demonstrated evidence of immunogenicity in these animals with generation of a serum antibody response specific to MuV infection and cytokine production consistent with infection. However, no live virus or viral RNA was detected in nasal washes, oral swabs, urine, faeces or tissue homogenates, and no animals exhibited clinical signs. We suggest results to be obtained from ferrets are limited in fundamental in vivo MuV research and that they may not be a suitable animal model for this virus.

A Streptococcus pneumoniae pathogenicity island encoding an ABC transporter involved in iron uptake and virulence.

Restricted iron availability is a major obstacle to growth and survival of pathogenic bacteria during infection. In contrast to Gram-negative pathogens, little is known about how Gram-positive pathogens obtain this essential metal. We have identified two Streptococcus pneumoniae genetic loci, pit1 and pit2, encoding homologues of ABC iron transporters that are required for iron uptake by this organism. S. pneumoniae strains containing disrupted copies of either pit1 or pit2 had decreased sensitivity to the iron-dependent antibiotic streptonigrin, and a strain containing disrupted copies of both pit1 and pit2 was unable to use haemoglobin as an iron source and had a reduced rate of iron uptake. The pit2- strain was moderately and the pit1-/pit2- strain strongly attenuated in virulence in mouse models of pulmonary and systemic infection, showing that the pit loci play a critical role during in vivo growth of S. pneumoniae. The pit2 locus is contained within a 27 kb region of chromosomal DNA that has several features of Gram-negative bacterial pathogenicity islands. This probable pathogenicity island (PPI-1) is the first to be described for S. pneumoniae, and its acquisition is likely to have played a significant role in the evolution of this important human pathogen.