Imaging polyhedral inclusion bodies of nuclear polyhedrosis viruses with second harmonic generation microscopy

We studied the polarization anisotropy of second harmonic generation (SHG) in polyhedral inclusion bodies (PIBs) of nuclear polyhedrosis viruses (NPV). Due to a body-centered-cubic arrangement of polyhedrin trimers, a characteristic SHG polarization property with a mixture of I23 and I3 symmetry was measured from PIBs. With this characteristic SHG anisotropy, it provides an intrinsic nonlinear signal for virus infection studies in living cells. With multimodal harmonic generation microscopy, we also demonstrated 3D imaging on PIBs of NPV in living cells. The distribution and the number of PIBs in intact infected cells can be revealed without the help of fluorescent labeling.