Surrogate markers for viral infections and other inflammatory responses

[0115] Bovine viral diarrhea virus (BVDV) infections are responsible for important economic losses due to reproductive wastage, and respiratory and digestive disease in cattle. Infection of the early developing fetus frequently results in persistent infection (Pt). PI animals are the main source of new infection in herd mates. The complex host-viral interactions resulting from persistent infection are minimally understood, particularly in the bovine host. We hypothesized that gene expression would differ in bloods collected from PI when compared to non-infected steers. In preliminary studies, bloods were collected from three PI or three control steers and were processed to yield total cellular RNA. Labeled RNA was used to screen six independent bovine Affymetrix DNA chips, and analyzed for fold-changes at the University of Colorado Health Sciences Center Microarray Facility. The top 100 up-regulated genes belonged to MHC class I (45-fold), antiviral (32-100 fold), transcription factor

[0127] We hypothesized that gene expression in white blood cells would differ in pregnant heifers carrying PI, TI or uninfected (control) fetuses. Non-vaccinated heifers were purchased, confirmed to be seronegative for BVDV and were placed on growing rations until they were old enough to be artificially inseminated and confirmed to be pregnant. Heifers were infected with noncytopathic BVDV2 on day 75 to generate PI fetuses, on day 175 to generate TI fetuses, or were not infected (n=6 heifers per treatment). Bloods were collected on days 0, 37, 75, 78, 82, 90, 120, 160, 175, 178, 182 and 190 of gestation for RNA, serology and virology. Fetuses were delivered on d. 190 by C-section and necropsied. Maternal blood mRNA on day 190 of gestation was screened using the bovine Affymetrix gene chips.

[0128] BVDV infection in heifers and fetuses was confirmed using ELISA and qRT-PCR. Infected pregnant heifers were seropositive for BVDV by days 15-45 post infection. PI fetuses weighed less and wer