Absence of lung immunopathology following respiratory syncytial virus (RSV) challenge in mice immunized with a recombinant RSV G protein fragment.

The relative immunopathogenic potential of a recombinant fusion protein incorporating residues 130-230 of respiratory syncytial virus (RSV-A) G protein (BBG2Na), formalin-inactivated RSV-A (FI-RSV), and phosphate-buffered saline (PBS) was investigated in mice after immunization and RSV challenge. FI-RSV priming resulted in massive infiltration of B cells and activated CD4(+) and CD8(+) T lymphocytes in mediastinal lymph nodes (MLN) and lungs, where eosinophilia and elevated IFN-gamma, IL-2, -4, -5, -10, and -13 mRNA transcripts were also detected. PBS-primed mice showed only elevated pulmonary IL-2 and IFN-gamma mRNAs, while an activated CD8(+) T cell peak was detected in MLN and lungs. Cell infiltration also occurred in MLN of BBG2Na-immunized mice. However, there was no evidence of T cell, B cell, or granulocyte infiltration or activation in lungs, while transient transcription of Th1-type cytokine genes was evident. The absence of pulmonary infiltration is unlikely due to insufficient viral antigen. Thus, this recombinant fusion RSV G fragment does not prime for adverse pulmonary immunopathologic responses.