Histometric demonstration of periastrocytic fibronectin loss during herpes simplex virus infection

Since Herpes simplex virus-type 1 (HSV-1) is liable to induce modifications and/or loss of immunoreactive fibronectin (FN) in cultured cells, our present goal was to determine whether such loss is attributable to FN binding impairment rather than cell detachment secondary to viral cytopathic effect. For this purpose, we resorted herein to an histometric approach for statistical evaluation of FN pattern in the course of HSV-1 infection of astroglial cell monolayers. The length of FN positive fibers was calculated by means of their tracing on a digitizer tablet; in the same field, cell nucleus count was performed. Recorded data allowed the calculation of an index as the ratio of the length of FN positive fibers over cell nucleus number. On comparing the indices between infected and control cultures, matricial FN loss was found in the former at 48 h post-inoculation, accompanied by cell fusion and retraction, though without cell detachment. A significant loss of FN was thus demonstrated as an event prior to severe cytopathic effect induced by viral infection.