Characterization of the systemic disease and ocular signs induced by experimental infection with Chlamydia psittaci in cats.

In addition to the commonly reported ocular signs, Chlamydia psittaci infection of kittens resulted in fever, lethargy, lameness and reduction in weight gain following ocular instillation of virulent organisms. The appearance of these systemic signs was late with respect to the appearance of ocular symptoms and occurred simultaneously with increasing levels of chlamydia-specific IgG. Measurement of acute phase reactants and IL-6 in plasma indicated that both became elevated concurrent with or slightly after the appearance of fever and remained elevated after the fever began to resolve.

Characterization of a synthetic peptide mimicking trypsin-cleavage site of rotavirus VP4.

A synthetic peptide corresponding to the trypsin cleavage site on the 84 k protein of bovine rotavirus was synthesized (VP4-peptide). This synthetic peptide could be cleaved by trypsin and therefore possessed the enzyme binding site present on the authentic protein. Further proof that this peptide mimicks the authentic trypsin cleavage site was the specific reaction of anti-peptide serum with the 84 k protein.

Formulation of the purified fusion protein of respiratory syncytial virus with the saponin QS-21 induces protective immune responses in Balb/c mice that are similar to those generated by experimental infection.

The feasibility of employing a vaccine composed of the purified fraction 21 of Quillaja saponaria (QS-21) and the fusion (F) protein of respiratory syncytial virus (RSV) to induce protective immune responses in the lower respiratory tract of Balb/c mice was examined. Our goal was to compare local and systemic immune responses with those induced following immunization with the protein adsorbed to aluminium hydroxide (F/ALOH) adjuvant or by experimental infection. Sera from mice vaccinated with the QS-21 formulation (F/QS-21) contained elevated anti-F protein IgG antibody titres that were dependent on the dose of QS-21 employed.

Molecular determinants of rotavirus virulence: localization of a potential virulence site in a murine rotavirus VP4.

The molecular basis of pathogenesis in vivo for a virulent mouse rotavirus (MRV) and a less virulent bovine rotavirus (BRV) were compared under in vitro and in vivo conditions. Obvious differences in the mobility of several genomic RNA segments were observed in one-dimensional gels. Under in vitro conditions, partial proteolytic peptide mapping identified differences between the two outer capsid proteins of these virus and no difference in inner capsid protein was observed.

Characterization of two rotaviruses differing in their in vitro and in vivo virulence.

The proteins, genomic RNA and disassembly conditions and pathogenesis in vivo for a virulent mouse rotavirus (MRV) and a less virulent bovine rotavirus (BRV) were compared. An obvious difference in the mobility of several genomic RNA segments were observed in one-dimensional gels. Reassortants obtained by replacement of gene 4 in BRV with MRV gene 4 indicated that the dose of the virus used and the clinical outcome in vivo was determined by gene segment 4.