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Comparison of experimental models for Streptococcus suis infection of conventional pigs 总被引：5，自引：0，他引：5 
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下载免费PDF全文 Francisco J. Pallars Patrick G. Halbur Cameron S. Schmitt James A. Roth Tanja Opriessnig Peter J. Thomas Joann M. Kinyon Dee Murphy Dagmar E. Frank Lorraine J. Hoffman 《Canadian journal of veterinary research》2003,67(3):225-228
Four different experimental models for Streptococcus suis-induced disease were compared to find a model that closely mimics naturally occurring disease in conventional pigs. Fourteen, 2-week old pigs free of S. suis type 2 were used in 2 experiments. In experiment 1, 3 pigs were inoculated intravenously (IV) and 3 pigs intranasally (IN) with S. suis. Two out of 3 of the IV-inoculated pigs exhibited signs of severe central nervous system disease (CNS) and were euthanized. Streptococcus suis type 2 was isolated from whole blood, joints, and serosal surfaces of both pigs. No clinical signs and no growth of S. suis were detected in the IN-inoculated pigs. In experiment 2, 4 pigs were inoculated IV and another 4 were inoculated IN with the same isolate as in experiment 1. One hour before inoculation the IN-inoculated pigs were given 5 mL of 1% acetic acid intranasally (IN-AA). All the IV-inoculated pigs showed CNS disease and lameness, and 2 of the pigs became severely affected and were euthanized. All the IN-AA inoculated pigs exhibited roughened hair coats and 2 pigs developed severe CNS disease and were euthanized. Streptococcus suis was isolated from the joints and blood of 3 pigs in the IV-inoculated group. Streptococcus suis was isolated from blood of 2 pigs, meninges of 3 pigs, and joints of 1 pig in the IN-AA inoculated group. Natural exposure to S. suis most likely occurs by the intranasal route. The IN-AA model should serve as a good model for S. suis-induced disease, because the natural route of exposure is intranasal and the IN-AA model was effective in inducing disease that mimics what is observed in the field. 相似文献
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Although the African Plate's northeastward absolute motion slowed abruptly 30 million years ago, the South Atlantic's spreading velocity has remained roughly constant over the past 80 million years, thus requiring a simultaneous westward acceleration of the South American Plate. This plate velocity correlation occurs because the two plates are coupled to general mantle circulation. The deceleration of the African Plate, due to its collision with the Eurasian Plate, diverts mantle flow westward, increasing the net basal driving torque and westward velocity of the South American Plate. One result of South America's higher plate velocity is the increased cordilleran activity along its western edge, beginning at about 30 million years ago. 相似文献
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Overview and initial results of the very long baseline interferometry space observatory programme 总被引：2，自引：0，他引：2
H Hirabayashi H Hirosawa H Kobayashi Y Murata PG Edwards EB Fomalont K Fujisawa T Ichikawa T Kii JEJ Lovell GA Moellenbrock R Okayasu M Inoue N Kawaguchi S Kameno KM Shibata Y Asaki T Bushimata S Enome S Horiuchi T Miyaji T Umemoto V Migenes K Wajima J Nakajima al et 《Science (New York, N.Y.)》1998,281(5384):1825-1829
High angular resolution images of extragalactic radio sources are being made with the Highly Advanced Laboratory for Communications and Astronomy (HALCA) satellite and ground-based radio telescopes as part of the Very Long Baseline Interferometry (VLBI) Space Observatory Programme (VSOP). VSOP observations at 1.6 and 5 gigahertz of the milli-arc-second-scale structure of radio quasars enable the quasar core size and the corresponding brightness temperature to be determined, and they enable the motions of jet components that are close to the core to be studied. Here, VSOP images of the gamma-ray source 1156+295, the quasar 1548+056, the ultraluminous quasar 0014+813, and the superluminal quasar 0212+735 are presented and discussed. 相似文献
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Vincent AL Thacker BJ Halbur PG Rothschild MF Thacker EL 《Journal of animal science》2006,84(1):49-57
The objective of this study was to determine whether host genetics play a role in susceptibility to the respiratory disease in growing pigs caused by the porcine reproductive and respiratory syndrome virus (PRRSV). Based on a previous study, 2 genetically diverse commercial lines of pigs that also were divergent in the susceptibility of monocyte-derived macrophages to PRRSV infection in vitro were selected for an in vivo challenge study. Based on the average percentage of infected macrophages for each line, a line derived from the Large White breed was characterized as fluorescence-activated cell sorting(hi) (FACS(hi)), and a line derived from Duroc and Pietrain breeds was characterized as FACS(lo). Pigs from each line were challenged at 6 wk of age with PRRSV VR-2385 and necropsied at 10 or 21 d after infection. Data collected included clinical evaluation of disease, virus titration in serum and lung lavage fluid, macroscopic lung lesion scores, and microscopic lung lesion scores. The FACS(lo) line had consistently more severe clinical disease compared with the FACS(hi) line in the early stages of infection. Differences between line means were significant (P < 0.05) at 10 d after infection for all variables just described, and the FACS(lo) line showed more severe signs of disease. By 21 d after infection, clinical signs and lesions were resolving, and the differences between lines were significant (P < 0.04) only for microscopic lung lesion scores but approached significance (P < 0.08) for virus titer in serum. At 21 d after infection, the relationship between the lines reversed; the FACS(hi) line had higher serum virus titers than the FACS(lo) line. This report provides evidence that strongly suggests the existence of a host genetic component in disease susceptibility to PRRSV and indicates that further study is warranted to define the cellular mechanisms that affect disease susceptibility. 相似文献
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Chao-Ting Xiao Priscilla F. Gerber Luis G. Giménez-Lirola Patrick G. Halbur Tanja Opriessnig 《Veterinary microbiology》2013,161(3-4):325-330
A novel porcine parvovirus designated as porcine parvovirus 2 (PPV2) was initially identified in Myanmar in 2001, in China during 2006–2007, and in Hungary in 2012. To investigate the presence and prevalence of PPV2 in the USA, a novel TaqMan® real-time PCR method was developed and used for a PPV2 survey using 483 lung samples, 185 fecal samples and 122 sera collected from pigs on 295 farms in 18 U.S. states. The overall prevalence of PPV2 was 20.7% (100/483) in lung samples and 7.6% (14/185) in fecal samples obtained from pigs of different age groups, and 1.6% (2/122) in sera or thoracic fluids obtained from neonatal pigs. Further genomic sequence comparison demonstrated that the 2011 U.S. PPV2 sequences have nucleotide identities of 95.4–97.7% with the 2006–2007 strains detected in China while the nucleotide identity was 94.7% with the 2001 strain detected in Myanmar, indicating persistent evolution of the virus. Phylogenetic and sequence homology analyses demonstrated a close relationship of PPV2 with members of the proposed genus PARV4-like virus, and the classification of PPV2 into this proposed genus is suggested. 相似文献
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A non-pharmaceutical, dietary option may be useful to manage clinical pseudopregnancy (PSP). To describe the effect of short-term food restriction on canine PSP, 16 privately owned, overtly pseudopregnant bitches were randomly assigned to one of the following groups: Limit-fed (increasing amounts of a restricted maintenance: 50%, 40%, 30% restriction for 2, 3 and 2 days respectively) during 7 days (n = 8) or Maintenance-fed of the same food and period (n = 8). The bitches were physically examined and blood samples were taken for prolactin and progesterone determinations on days 2, 5 and 8. By day 8, none of the bitches had completely regressed the condition although all (8/8) the animals of the Limit-fed and two (25%) of the Maintenance-fed group improved in condition decreasing mammary size and secretion (p < 0.05). No day or group effects were observed for serum prolactin and progesterone concentrations (>0.05). It is concluded that although an 8-day food restriction did not cure PSP, it seemed to hasten PSP signs involution in these bitches. No endocrine change was related to these clinical findings. 相似文献
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Hemann M Shen HG Beach NM Meng XJ Halbur PG Opriessnig T 《Veterinary research communications》2012,36(3):187-193
Xenotransplantation of tissues from transgenic pigs with desired genetic modifications such as CD46 expression help minimize xenograft rejections. However, CD46 is a known receptor for some viruses. In this study, pigs transgenic for human CD46 (CD46-TG) and appropriate non-transgenic (non-TG) control pigs were utilized to determine possible differences in the level of replication and shedding of porcine circovirus type 2 (PCV2). Non-TG and CD46-TG were blocked by transgenic status and randomly divided into three groups: Non-TG negative controls (n?=?3), non-TG-PCV2 (n?=?10; PCV2a?=?5, PCV2b?=?5), and CD46-TG-PCV2 (n?=?6; PCV2a?=?3, PCV2b?=?3). Blood, oral, nasal and fecal swabs were collected at regular intervals from the day of arrival until 70 days post inoculation (DPI). All samples were tested by quantitative real-time PCR for the presence of PCV2 DNA and serum was tested for presence of PCV2 antibodies by ELISA. Overall, the main effects "transgenic status" and "PCV2 subtype" had no influence on degree of PCV2 viremia and shedding or the anti-PCV2 humoral immune response in CD46-TG-PCV2 pigs compared to non-TG-PCV2 pigs. Differences in PCV2 concentrations between non-TG-PCV2 and CD46-TG-PCV2 pigs were minimal and limited to DPI 35 in sera, DPI 7 in fecal swabs and DPI 5 in nasal swabs when CD46-TG-PCV2 pigs had significantly higher concentrations of PCV2 DNA. At DPI 1, CD46-TG-PCV2 pigs had significantly lower concentrations of PCV2 DNA in oral swabs. Under the study conditions, the presence of human CD46 in transgenic pigs had no effect on PCV2 infection in otherwise healthy pigs capable of a normal immune response. 相似文献
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Opriessnig T Gauger PC Faaberg KS Shen H Beach NM Meng XJ Wang C Halbur PG 《Veterinary microbiology》2012,158(1-2):69-81
To determine differences in infection kinetics of two temporally and genetically different type 2 porcine reproductive and respiratory syndrome virus (PRRSV) isolates in vivo with and without concurrent porcine circovirus (PCV) type 2a or 2b infection, 62 pigs were randomly assigned to one of seven groups: negative controls (n=8); pigs coinfected with a 1992 PRRSV strain (VR-2385) and PCV2a (CoI-92-2a; n=9), pigs coinfected with VR-2385 and PCV2b (CoI-92-2b; n=9), pigs coinfected with a 2006 PRRSV strain (NC16845b) and PCV2a (CoI-06-2a; n=9), pigs coinfected with NC16845b and PCV2b (CoI-06-2b; n=9), pigs infected with VR-2385 (n=9), and pigs infected with NC16845b (n=9). Blood samples were collected before inoculation and at day post-inoculation (dpi) 3, 6, 9 and 12 and tested for the presence of PRRSV antibody and RNA, PCV2 antibody and DNA, complete blood counts, and interferon gamma (IFN-γ) levels. Regardless of concurrent PCV2 infection, VR-2385 initially replicated at higher levels and reached peak replication levels at dpi 6. Pigs infected with VR-2385 had significantly higher amounts of viral RNA in serum on both dpi 3 and dpi 6, compared to pigs infected with NC16845b. The peak of NC16845b virus replication occurred between dpi 9 and dpi 12 and was associated with a delayed anti-PRRSV antibody response in these pigs. PCV2 coinfection resulted in significantly more severe macroscopic and microscopic lung lesions and a stronger anti-PRRSV IgG response compared to pigs infected with PRRSV alone. This work further emphasizes in vivo replication differences among PRRSV strains and the importance of coinfecting pathogens. 相似文献