Lung and Nasal Lesions Caused by a Swine Chlamydial Isolate in Gnotobiotic Pigs

Abstract

Abstract. Abstract. The objective of this study was to determine whether a chlamydial isolate recovered from nasal swabs from swine with pneumonia could cause pneumonia and rhinitis in gnotobiotic pigs. The identity of the isolate currently is unknown, but it shares characteristics with Chlamydia trachomatis. After propagation in Vero cells and preparation of the inoculum (2.5 x 10 10 inclusion-forming units/ml), Chlamydiae were instilled into nostrils (1.0 ml/nostril) and lungs (2.0 ml intralaryngeally) of 15 anesthetized 3-day-old gnotobiotic piglets. Five age-matched gnotobiotic piglets were anesthetized and sham infected with uninfected cell culture lysates. Two treated piglets were moribund and 2 were severely dyspneic prior to necropsy 7 days postinfection (DPI), whereas remaining treated piglets showed mild dyspnea upon exertion throughout the study. All treated piglets developed diarrhea. All treated piglets necropsied 7-21 DPI had extensive consolidation in cranial, middle, and accessory lung lobes; a majority of these piglets also had extensive consolidation in the caudal lobes. Treated piglets necropsied 28 and 35 DPI had a lobular pattern of consolidation in all lung lobes. Histologically, lesions in lungs from treated piglets necropsied 7, 14, and 21 DPI were characterized by bronchointerstitial pneumonia with foci of type II pneumocyte hypertrophy and hyperplasia; pneumocytes and bronchial and bronchiolar epithelial cells were markedly vacuolated. Alveolar macrophages, peribronchitis, peribronchiolitis, and perivasculitis were seen in lungs from treated piglets necropsied 28 and 35 DPI; those necropsied 28 DPI also had foci of lymphohistiocytic and plasmacytic infiltrates. Turbinate lesions in all treated piglets were characterized by mild multifocal lymphoplasmacytic and occasionally neutrophilic rhinitis. Immunohistochemistry detected chlamydial antigen in bronchial and bronchiolar epithelial cells, pneumocytes, and inflammatory cells in treated piglets necropsied 7, 14, and 21 DPI. Positive staining was limited to alveolar macrophages in treated piglets necropsied 28 and 35 DPI. Chlamydial antigen was detected in turbinate epithelial cells at all necropsy intervals. Ultrastructurally, chlamydiae were seen with glycogen particles in vacuoles or free in the cytoplasm of bronchial and bronchiolar epithelial cells and pneumocytes. The results indicated that the chlamydial isolate used in this Chlamydiae have been associated with pneumonia, 17 enteritis, 11,13 conjunctivitis, 14 polyarthritis, 6 pericarditis, 19 perinatal mortality, 22 and reproductive disorders 15,21 in swine; however, the diagnostic and economic significance is unknown. Most of these reports have been based on histopathology, electron microscopy, and in some cases the isolation of chlamydiae. Many of the chlamydial isolates recovered from these disease syndromes are no longer available for study, and only a limited number of these isolates have been characterized.We recently recovered a chlamydial isolate from nasal swabs from pigs...

An experimentally inducedChlamydiasuis infection in pigs results in severe lung function disorders and pulmonary inflammation

“…The knowledge about the involvement of Chlamydiaceae in the porcine respiratory disease complex is still limited and reports in the literature are very inconsistent. While lung function was not affected in symptom-free pigs with a naturally acquired presence of chlamydiae in the respiratory system [32], a clear pathogenic potential of Chlamydia species for the porcine respiratory system has been proven experimentally [32,35].…”

“…In order to evaluate the aetiological importance of C. suis, an experimental challenge model of aerosol infection was established by our group [38]. In contrast to the model described by Rogers et al [35] where three day old gnotobiotic piglets were found to be susceptible to respiratory chlamydial infection, the pigs challenged in our model were conventionally raised, older (approximately six weeks), and had even a positive carrier status for chlamydiae [38]. Despite lower infection dosages compared to the model described by Rogers et al [35], they responded to the aerosol challenge of C. suis with acute phase reactions, severe clinical signs and significant increases of chlamydiaspecific antibody titres [38].…”

Intestinal Lesions Caused by a Strain ofChlamydia Suisin Weanling Pigs Infected at 21 Days of Age

“…Vaginal and fecal swab specimens were collected from each sow at farrowing and processed for the isolation of chlamydiae as previously described. 13 Pigs and experimental design. Twenty-one newborn pigs were identified by ear tags, and each pig was given 200 mg of iron dextran intramuscularly after they had nursed their respective sows for 24 hr.…”

“…Fecal swab and intestinal specimens collected at necropsy from 2 6-wk-old diarrheic pigs were processed for the isolation of chlamydiae as previously described. 13,15 Chlamydial isolates were analyzed by polymerase chain reaction (PCR) amplification of the major outer membrane protein genome using the primers and basic techniques as reported previously. 2 The PCR product was verified by electrophoresis in 1.5% agarose.…”

“…Chlamydia suis strain R27 was grown in confluent Vero cell monolayers and harvested as previously described. 13 Chlamydiae were concentrated approximately 10-fold by pelleting in a centrifuge and resuspending in sucrose-phosphate-glutamine buffer. 15 The inoculum was stored in ampules at Ϫ70 C. The dosage of inoculum was determined to be approximately 10 10 inclusionforming units (IFU)/ml by titration in 24-hr Vero cell monolayers grown in 96-well multiwell dishes.…”