Ultrastructural pathology and temporal patterns of viral replication and lesion development following mouse kidney parvovirus infection in B6,CD1,and NSG mice

Abstract

Mouse kidney parvovirus (MKPV) causes inclusion body nephropathy, resulting in clinical signs and mortality in immunodeficient mice and subclinical infection in immunocompetent mice. While late-stage renal lesions and viral replication have been characterized, a comprehensive multisystemic investigation of MKPV infection from the initial to the late stages of infection has not been conducted. Our goal was to investigate lesions and viral replication in all major organs at multiple stages of MKPV infection in immunocompetent C57BL/6NCrl (B6) and Crl: CD1(ICR) (CD1) mice and immunodeficient NOD. Cg-Prkdc ^scid Il2rg ^tm1Wjl /SzJ (NSG) mice. Following experimental oronasal inoculation with MKPV, mice were evaluated at 15 time points from 1.5 to 112 days post-inoculation (DPI) by histology and in situ hybridization for MKPV RNA on all major organs, as well as immunohistochemistry for markers of immune cells and renal tubular injury. In all strains, the gastrointestinal mucosa was the initial site of viral replication beginning at 3 DPI and persisting through the study without associated lesions. In B6 and CD1 mice, viral replication was first detected in renal tubules on 28 and 14 DPI, respectively, and lymphoplasmacytic tubulointerstitial nephritis was first evident on 63 and 49 DPI, respectively. B6 mice displayed the lowest levels of renal viral replication and lesion severity. In contrast, renal viral replication was highest in NSG mice; the virus was first detected on 42 DPI and in association with tubular degeneration from 63 DPI. Electron microscopy on kidney tissues of infected mice revealed parvoviral virions, nuclear replication, and assembly compartments for the first time.