In Utero Infection by Porcine Reproductive and Respiratory Syndrome Virus Is Sufficient To Increase Susceptibility of Piglets to Challenge by Streptococcus suis Type II
| Autor: | Talmage T. Brown, Craig Altier, Jinsheng Xu, M. B. McCaw, Wen-hai Feng, Mary B. Tompkins, W. Gomez, D. Benfield, Scott M. Laster |
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| Rok vydání: | 2001 |
| Předmět: |
Streptococcus suis
Swine animal diseases Immunology Porcine Reproductive and Respiratory Syndrome Spleen Microbiology Virus Leukocyte Count fluids and secretions Pregnancy Virology Streptococcal Infections medicine Animals Porcine respiratory and reproductive syndrome virus Respiratory system biology integumentary system Uterus virus diseases Cell Differentiation respiratory system biology.organism_classification Porcine reproductive and respiratory syndrome virus Infectious Disease Transmission Vertical medicine.anatomical_structure In utero Insect Science Tonsil Colostrum Pregnancy Animal Pathogenesis and Immunity Female Disease Susceptibility |
| Zdroj: | Journal of Virology |
| ISSN: | 0022-538X |
| DOI: | 10.1128/jvi.75.10.4889-4895.2001 |
| Popis: | Porcine reproductive and respiratory syndrome (PRRS) consistently elevates the frequency of disease and mortality in young pigs. Many different secondary bacterial diseases occur in PRRS virus (PRRSV)-infected pigs. However, to date, establishing a reproducible experimental model of PRRSV infection in weaned pigs, with subsequent clinical disease following secondary bacterial challenge, has been difficult. PRRSV is frequently isolated during outbreaks from weak-born piglets affected by secondary bacterial diseases. This study was performed to investigate the potential role of intrauterine PRRSV infection on piglet susceptibility to secondary bacterial infection. PRRSV-free pregnant sows were intranasally infected at 98 days of gestation with PRRSV strain SD 23983. All piglets born to the PRRSV-infected sows were viremic. Piglets were removed from the sows at birth and deprived of colostrum. Piglets from PRRSV-infected and noninfected sows were randomly assigned to Streptococcus suis challenge or control subgroups. At 5 days of age, piglets were challenged intranasally with strain MN 87555 of S. suis type II. Total and differential leukocyte counts were performed on blood samples collected at 3 days of age. The numbers of leukocytes, lymphocytes, and monocytes were significantly reduced in the PRRSV-infected piglets. Lesions were observed in bone marrow, brain, lung, heart, spleen, lymph node, tonsil, and thymus of PRRSV-infected piglets. Thymus/body weight ratios of in utero PRRSV-infected piglets were significantly reduced compared to those of non-PRRSV-infected piglets, and thymic lesions were characterized by severe cortical depletion of thymocytes. Lesions were not observed in piglets born to PRRSV-free sows. Overall, 20 out of 22 piglets in the PRRSV- S. suis dual-infection group died within 1 week after challenge with S. suis (10 of 11 in each of two trials). This contrasts with 1 of 18 piglets in the PRRSV-infection-only group and 5 of 23 piglets in the S. suis -challenge-only group (1 of 12 in trial 1 and 4 of 11 in trial 2). No piglets died in the uninfected control groups. Most of the piglets in the PRRSV- S. suis dual-infection group developed suppurative meningitis. S. suis type II was recovered from their brains and joints. These results indicate that in utero infection by PRRSV makes piglets more susceptible to infection and disease following challenge by S. suis type II. In utero infection by PRRSV may provide a useful model to study the interaction between PRRSV and bacterial coinfections in piglets. |
| Databáze: | OpenAIRE |
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