To study the pathogenicity of the Brazilian bovine viral diarrhea virus (BVDV) type 1a 241.10 isolate, four calves were intranasally inoculated with a viral suspension containing 107.2 TCID50 mL-1. One calf was left uninoculated and kept in contact with the other calves to investigate viral transmissibility. After inoculation, the animals were monitored daily for clinical signs of infection. The presence of the virus in the blood and nasal secretions was confirmed by virus isolation in cell culture. White blood cells were quantified prior to and every 3 days after infection, and the presence of antibodies was checked every 7 days, starting at day 0 until day 42 post-inoculation (pi). After infection, nasal and ocular serous secretions were observed between days 1 and 5 pi, along with a mild cough from days 2 to 4 pi; however, no severe clinical signs were present. Body temperature was slightly elevated between days 4 and 6 pi. The control calf did not develop any of the signs observed in the infected animals. Cell culture-mediated virus isolation confirmed viremia between days 4 and 8 pi and the presence of the virus in the nasal secretions between days 1 and 10 pi. All infected animals showed a decrease in white blood cell count. Antibodies could be detected from day 14 pi, and these levels remained high until day 35 pi. The control calf had no viremia, viral presence in nasal secretions, or positive serology, indicating the absence of viral transmission. Thus, isolate BVDV 1a 241.10 has low pathogenicity and transmissibility but retains immunosuppressive capacity.
The study describes the genetic identification, clinical, and epidemiological characteristics of an outbreak of equine infectious anemia occurring in the state of Rio Grande do Sul, Brazil. Three animals kept in the periurban region of Uruguaiana city tested positive for the AGID test. The serology was performed as a requirement for transit. None of the animals showed clinical signs of infection, one animal was necropsied, and the others were stolen. In the post-mortem examination, no macroscopic changes were observed, and microscopically, discrete hemosiderosis was detected in fragments of the liver and spleen. Amplifying and sequencing a proviral DNA fragment in blood, spleen, and mesenteric lymph node samples confirmed EIAV infection. Phylogenetic analysis of the first sequenced EIAV sample from the Rio Grande do Sul State indicates a high similarity with other Brazilian samples. Results confirmed the viral presence in the state’s herds and described epidemiological and virological characteristics of EIA that contribute to the maintenance and dissemination of the virus in herds.
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