if you're going to throw up a diversion, pick wisely......
Am J Pathol. 2003 Oct;163(4):1341-55.
Specific history of heterologous virus infections determines anti-viral immunity and immunopathology in the lung.
Chen HD, Fraire AE, Joris I, Welsh RM, Selin LK.
Department of Pathology, University of Massachusetts Medical School, Worcester, Massachusetts.
Having previously shown that previous immunity to one virus can influence the host response to a subsequent unrelated virus, we questioned whether the outcome to a given virus infection would be altered in similar or different ways by previous immunity to different viruses, and whether immunity to a given virus would have similar effects on all subsequent infections. In mouse models of respiratory viral infections, immunity to lymphocytic choriomeningitis virus (LCMV), murine cytomegalovirus (MCMV), or influenza A virus enhanced both Th1-type cytokine responses and viral clearance in the lung on vaccinia virus infection. A common pathological feature was the presence of chronic mononuclear infiltrates instead of the acute polymorphonuclear response seen in the infected nonimmune mice, but some pathologies such as enhanced bronchus-associated lymphoid tissue and bronchiolitis obliterans were unique for the immunizing virus, LCMV. Immunity to influenza virus influenced subsequent infections diversely, inhibiting vaccinia virus but enhancing LCMV and MCMV titers and completely altering cytokine profiles. Influenza virus immunity enhanced the mild mononuclear responses usually observed during acute infections with MCMV or LCMV in nonimmune mice, but unique features such as enhanced bronchiolization and mononuclear consolidation occurred during MCMV infection of influenza virus-immune mice. Heterologous immunity induced two patterns of disease outcome dependent on the specific virus infection sequence: improved, if the acute response switched from a neutrophilic to a lymphocytic response or worsened, if it switched from a mild to a severe lymphocytic response. Heterologous immunity thus occurs between many viruses, resulting in altered protective immunity and lung immunopathology, and this is influenced by the specific virus infection sequence.
(This sort of study, eventually, should help us to protect against any viral bioterror attack. For emerging pathogens (like SARS), however, there'd be no known "responder footprint"...... we don't know if lungs are torn apart by neutrophils, T cells, or ????. *True* heterologous protection, from the stand of an induced, protective T cell response? First, don't count on it. But, more importantly, we'll know nothing of any antigen profile for emerging pathogens, and a combo of small molecule "first responder prophylaxis" and vaccination is the answer for any known bioterror agent. But the question is an intriguing one...... if SARS hits again, would there be an increased or decreased survival among those who immediately headed for their local preschool to lick every fomite in sight?) |
