ABSTRACT
Murine cytomegalovirus (MCMV) m137 null mutants, Deltam137A and Deltam137B, were generated by inserting a gpt cassette into a deleted region of the open reading frame. A polyclonal antiserum produced to an Escherichia coli expressed gst-m137 fusion protein was used to show that a 38 kDa polypeptide corresponding to the predicted m137 gene product was present in NIH 3T3 fibroblasts infected with wild-type MCMV but was not detected in Deltam137 infected cells. The protein did not fractionate with infected cell membranes and was not detectable in purified wild-type virions. Plaque size, plaque morphology, and viral yield did not differ significantly between Deltam137 and wild-type MCMV infected 3T3 fibroblasts. The results showed that deletion of the 38 kDa protein did not negatively effect viral growth in 3T3 fibroblasts indicating that the m137 gene product is not essential for replication in these cells. In vivo analysis revealed that two independently isolated m137 mutants showed a significant delay in time until death but ultimately killed 100% of the mice in a SCID mouse model of virulence.
Subject(s)
Herpesviridae Infections/virology , Muromegalovirus/metabolism , Viral Proteins/physiology , 3T3 Cells , Animals , Herpesviridae Infections/mortality , Mice , Mice, SCID , Muromegalovirus/genetics , Muromegalovirus/physiology , Mutagenesis , Viral Plaque Assay , Viral Proteins/genetics , Virus ReplicationABSTRACT
Human respiratory syncytial virus (RSV), a paramyxovirus, is a major cause of acute upper and lower respiratory tract infections in infants, young children, and adults. RFI-641 is a novel anti-RSV agent with potent in vitro and in vivo activity. RFI-641 is active against both RSV type A and B strains. The viral specificity and the large therapeutic window of RFI-641 (>100-fold) indicate that the antiviral activity of the compound is not due to adverse effects on normal cells. The potent in vitro activity of RFI-641 can be translated to efficacy in vivo: RFI-641 is efficacious when administered prophylactically by the intranasal route in mice, cotton rats, and African green monkeys. RFI-641 is also efficacious when administered therapeutically (24 h postinfection) in the monkey model. Mechanism of action studies indicate that RFI-641 blocks viral F protein-mediated fusion and cell syncytium formation.
