Two techniques performed on skin biopsy samples (ear notches), immunohistochemistry (IHC) and antigen-capture ELISA (AgELISA), were compared for detection of bovine viral diarrhea virus (BVDV) persistent infection (PI) in 559 Angus calves between the ages of 1 and 5 months. The calves also were tested for BVDV infection using virus isolation (VI) and reverse transcription (RT)-PCR on buffy coat samples and for antibodies to BVDV types la and 2 by serum neutralization (SN). Sixty-seven of 559 (12.0%) calves tested positive at initial screening by IHC, AgELISA, or VI, and all 67 were kept for a minimum of 3 months and retested monthly by IHC, AgELISA, VI, RT-PCR, and SN. Of the calves positive at initial screening, 59/67 (88.1%) were determined PI and 8/67 (11.9%) were determined acutely infected. Both IHC and AgELISA detected 100% of PI calves; however, IHC and AgELISA also detected 6 and 8 acutely infected calves, respectively, at initial screening. Furthermore, IHC and AgELISA continued to detect 3 and 4 acutely infected calves, respectively, 3 months after initial screening. Three acutely infected calves had IHC staining indistinguishable from PI calves at initial screening. Both IHC and AgELISA are accurate at detecting BVDV-infected calves, but veterinarians and producers should be advised that both tests detect some calves acutely infected with BVDV in addition to PI animals. Repeat testing using VI or RT-PCR on buffy coat samples should be performed at 30 days after initial screening to conclusively discriminate between acute and PI.

Thecal vascular tissue and blood cells were studied by light, transmission, and scanning electron microscopy during ovulation in the ewe. Cross-sectional areas of vascular lumens increased after the preovulatory surge in luteinizing hormone, decreased before ovulation, and then increased again as corpora lutea formed. Numbers of blood vessels per unit area of thecal tissue declined just before ovulation, then increased during luteinization. The follicular stigma that develops near the time of ovulation was completely void of blood vessels. These findings were paralleled chronologically by evidence of vasodilation, increased vascular permeability, tissue edema, congestion, ischemia, vascular injury, and angiogenesis. Neutrophils and eosinophils migrated out of the vascular compartment before ovulation. Around the time of ovulation, there were masses of extravasated blood in thecal tissue, and numerous platelets adhered to damaged vascular endothelium. Extravasated monocytes/macrophages were evident after ovulation. Numbers of extravascular lymphocytes remained relatively constant, but the lymphocytes were often marginated along endothelium in ovulatory and postovulatory follicles. Basophilic cells accumulated in association with the development of new capillaries during luteinization. Our observations are consistent with the concept that periovulatory follicular processes include acute inflammation, tissue damage, glandular transformation, and healing.

A noncytopathic type 1a bovine viral diarrhea virus (BVDV) was isolated from a free-ranging yearling female mule deer (Odocoileus hemionus) from northwestern Wyoming (USA). The mule deer was emaciated, weak, and salivating, and Arcanobacterium pyogenes was cultured from lung abscesses. Bovine viral diarrhea virus was isolated from lung, however, BVDV antigen was not detected by immunohistochemistry. The BVDV genotype was determined by reverse transcriptase polymerase chain reaction and the RNA sequences from the 5'UTR and E2 genes compared with sequences of a type 1a BVDV isolated from cattle from the same area as the deer. The sequences from the deer BVDV were distinct from those of the bovine type 1a BVDV, but similar to other bovine type 1a BVDVs. Seventy-four (60%) of 124 sera collected from mule deer in this area had serum neutralizing antibody titers to type 1a BVDV of > or = 1:32. The high prevalence of seropositive mule deer and isolation of BVDV suggests that this virus circulates in the mule deer population. The isolate described in this report is the second reported BVDV isolate from free-ranging deer in North America and the first from a mule deer.

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