Interaction with vesicular stomatitis virus-infected BALB/c3T3 cells inhibits the synthesis of nitric oxide in activated murine bone marrow culture-derived macrophages

Bone marrow-culture-derived macrophages activated with interferon-gamma and Lipopolysaccharide produced less nitric oxide (NO) when cultured with vesi cular stomatitis virus (VSV)infected BALB/c3T3 (3T3-VSV) than macrophages a ctivated in an identical maimer and cultured alone, with uninfected BALB/c3 T3 (3T3), or with]P815, However, all four groups of macrophages produced ne arly the same amount of interleukin-6 (IL-6), Addition of VSV to activated macrophages did not change the amount of NO produced. The amount of NO gene rated by two non-macrophage sources of NO was not affected by the presence of either P815 or 3T3-VSV. Reverse transcriptase-polymerase chain reaction showed a decrease in the amount of inducible nitric oxide synthase (iNOS) b ut not IL-6 mRNA frost macrophages cocultured with 3T3-VSV compared with ma crophages cocultured with P815, The reduction in iNOS mRNA was confirmed by ribonuclease protection assay. When RAW 264.7 transfected with an iNOS reg ulatory construct were activated and incubated with 3T3-VSV there was a dec rease hi the expression of the reporter luciferase gene and NO production b ut not IL-6 production compared with cells incubated with either medium alo ne or with P815.