Comparison of Pathogenicity of Various Isolates of Bordetella Bronchiseptica in Young Pigs

Eight groups of 12-to 24-hour-old pigs were procured from a respiratory disease-free herd of swine and reared in isolation using a box-rearing procedure. They were inoculated intranasally at 3 days of age with different isolates of Bordetella bronchiseptica.

It was found at necropsy 4 weeks post-inoculation that 4 isolates of swine origin, an isolate of rabbit origin and an isolate of cat origin caused mild to moderate turbinate atrophy in 22 of 24 pigs. An isolate of rat origin caused mild turbinate atrophy in 1 of 4 pigs and an isolate of dog origin caused no turbinate atrophy. Pneumonia was present in most of the pigs inoculated with the swine, cat and rabbit isolates.

Bordetella bronchiseptica was recovered in heavy growth from the nasal and tracheal exudate collected at necropsy from pigs inoculated with the 4 isolates of swine origin and the isolate of cat origin. Fewer organisms were isolated from nasal exudate collected from pigs inoculated with the rat, dog and rabbit isolates.

     

Experimental atrophic rhinitis in 2 and 4 month old pigs infected sequentially with Bordetella bronchiseptica and toxigenic type D Pasteurella multocida.

Experimental infections with Bordetella bronchiseptica and/or toxigenic type D Pasteurella multocida were studied in 2- and 4-month-old primary specific-pathogen-free pigs. None of the 2-month-old pigs inoculated with B. bronchiseptica or P. multocida alone developed turbinate atrophy. All the pigs inoculated with B. bronchiseptica (10(7) CFU/head) and P. multocida (10(9) CFU/head for 5 consecutive days) together, however, developed clinical and post-mortem signs of atrophic rhinitis (AR) similar to the naturally occurring disease. Slight to severe turbinate atrophy was observed in the 4-month-old pigs inoculated with B. bronchiseptica and P. multocida (at the same concentration as above) at necropsy.     

Toxigenic type A Pasteurella multocida as a causative agent of nasal turbinate atrophy in swine.

Although no clinical signs of atrophic rhinitis (AR) were recognized in 2- and 5-week-old pigs, approximately 60% of 2- to 6-month-old pigs showed clinical signs of AR in an affected pig farm. None of the pigs had normal turbinate at slaughter. Bordetella bronchiseptica was not isolated from any of the pigs before onset and incipient stage of the outbreak (2-week to 2-month-old). Pasteurella multocida of capsular type D was not isolated from any of those pigs. However, toxigenic P. multocida of capsular type A was isolated from a number of the pigs immediately before onset and incipient stage of the outbreak. Thirty-six-day-old primary specific-pathogen-free pigs were inoculated intranasally with a toxigenic type A P. multocida isolated from a 5-week-old pig. Severe nasal turbinate atrophy was observed in those pigs which were necropsied at 3 weeks post-inoculation. This is the first report on outbreak of severe nasal turbinate atrophy induced by toxigenic type A P. multocida in Japan.     

Bordetella bronchiseptica and toxigenic type D Pasteurella multocida as agents of severe atrophic rhinitis of swine

Bordetella bronchiseptica and toxigenic type-D Pasteurella multocida were cultured from pigs in each of five herds diagnosed as having severe atrophic rhinitis (AR). B. bronchiseptica alone, P. multocida alone, or both organisms isolated from four herds were inoculated intranasally into 1-week-old gnotobiotic pigs which were necropsied 4 weeks post-inoculation (PI). Nasal turbinate atrophy in B. bronchiseptica-inoculated pigs was moderate to severe, while P. multocida-inoculated pigs had slight to severe atrophy. Pigs inoculated with both organisms had moderate to complete turbinate atrophy. P. multocida was reisolated at necropsy from all pigs receiving the organism except those having no turbinate damage. B. bronchiseptica and P. multocida from a fifth herd were simultaneously inoculated into six naturally farrowed 6-day-old SPF pigs. Necropsy performed 4 weeks PI revealed severe to complete turbinate atrophy. Nasal turbinates were normal for control pigs in both experiments.     

Association of growth performance with atrophic rhinitis and pneumonia detected at slaughter in a conventional pig herd in Hungary

The influence of atrophic rhinitis (AR) and pneumonia on growth performance was assessed in a conventional farrow-to-finish pig farm affected by both diseases. All tested pigs (n = 138) were individually weighed at birth, at weaning, at moving to the growing/finishing unit, and at slaughtering. The extent (grade) of turbinate atrophy and lung consolidation attributable to pneumonia was determined in each pig at slaughter. A negative correlation was found between birth weight and the prevalence of nasal lesions at slaughter, suggesting that pigs born with smaller weight may be more susceptible to AR. The growth performance of the pigs also showed a negative correlation with the degree of turbinate atrophy. In the nursery period, the average daily gain (ADG) of pigs with moderate/severe turbinate atrophy was 13.3% lower than that of animals with healthy snouts. In the finishing period, pigs with mild AR lesions had an ADG reduction of 6.2%, while pigs with severe AR lesions had a significant, 9.4% reduction in ADG as compared to the AR-free pigs. The extent of weight gain reduction over the whole life cycle was very similar (approximately 6%) in the pigs having either AR or pneumonia alone. In those pigs where both respiratory diseases were present, their effects seemed to be added up (11.5%); however, nasal lesion scores and percentage of lung consolidation did not show statistically apparent interactive effects on growth performance.     

Immunogenicity and safety of an attenuated Bordetella bronchiseptica vaccine in pigs

The immunogenicity and safety of an attenuated Bordetella bronchiseptica vaccine for swine atrophic rhinitis (AR) was evaluated in 22 hysterectomy-produced, colostrum-deprived pigs and 18 conventional pigs. None of 8 pigs inoculated at 7 days of age intranasally with greater than or equal to 3 X 10(5) colony-forming units (CFU) of vaccinal strain/pig and 2 of 5 pigs inoculated at 7 days of age intranasally with 3 X 10(4) CFU of the vaccinal strain/pig developed AR after intranasal challenge exposure with a virulent strain at postinoculation week (PIW) 3. The remaining 3 vaccinated pigs and 4 nonvaccinated pigs developed AR. Thirteen pigs were inoculated intranasally with 3 X 10(6) to 3 X 10(9) CFU of the vaccinal strain at 7 days of age. At PIW 12, the pigs were killed and necropsied. None of the pigs had clinical signs of AR and/or pneumonia. Virulence was studied by transmission of vaccinal strain through 3 serial growing passages on the nasal mucosa of a litter of hysterectomy-produced colostrum-deprived pigs. Inoculum (nasal swab samples from 2 pigs 4 days after inoculation with 10(8) CFU of vaccinal strain at 5 days of age) was inoculated into the nasal cavity of 2 nonvaccinated pigs. This procedure was repeated 3 times. After the 1st passage, the vaccinal strain was recovered on postinoculation day 4, but after postinoculation day 4, the vaccinal strain was not recovered until the end of the 3rd passage. Turbinate atrophy or pneumonia was not recognized in these inoculated pigs. The vaccinal strain provided immunogenicity without ill effects.     

Induction of nasal turbinate atrophy in germ-free pigs, using Pasteurella multocida as well as bacterium-free crude and purified dermonecrotic toxin of P multocida

To establish the role of the dermonecrotic toxin (DNT) of Pasteurella multocida in the cause and pathogenesis of atrophic rhinitis, germ-free pigs were inoculated with several strains of P multocida, crude DNT, or purified DNT. In some experiments, the aforementioned inocula were combined with Bordetella bronchiseptica. All DNT-producing P multocida strains induced severe turbinate atrophy. Histologic examination of the remnants of the nasal turbinates revealed intact, but undulated, ciliated epithelium and numerous osteoclasts. Inflammation was minimal or absent. A DNT-producing B bronchiseptica strain induced only mild turbinate atrophy. The lesions were characterized histologically by loss of cilia and ciliated cells and by an infiltration of predominantly mononuclear cells. Bone formation seemed impaired. Turbinate lesions were most severe in pigs infected with a combination of B bronchiseptica and a DNT-producing P multocida strain. Intranasal administration of sterile DNT-containing culture filtrate of P multocida or purified DNT of P multocida did not result in turbinate atrophy. In contrast, turbinate atrophy developed when these preparations were injected IM or when intranasal administration of DNT was preceded by inoculation of B bronchiseptica.     

Relationship of porcine cytomegalovirus and B bronchiseptica to atrophic rhinitis in gnotobiotic piglets.

Both porcine cytomegalovirus (PCMV) and Bordetella bronchiseptica produced rhinitis and pneumonia when inoculated intranasally into young gnotobiotic pigs. With PCMV the nasal lesions were confirmed to the lamina propria, while Bordetella produced atrophy of the turbinate bones and hyperplasia and degeneration of the nasal epithelium. Some exacerbation of the lesions was observed in the nasal mucosa of pigs given both agents, but the degree of bone atrophy was not increased.     

Turbinate atrophy in gnotobiotic pigs intranasally inoculated with protein toxin isolated from type D Pasteurella multocida

Three doses (75 micrograms, 25 micrograms, and 25 micrograms) of purified toxin isolated from a toxigenic strain of type D Pasteurella multocida were given (by atomizer) into the right nasal cavities of each of 10 gnotobiotic pigs on the 21st, 24th, and 27th days of age, respectively. Inoculated pigs (usually 2) and 1 noninoculated control pig each were necropsied on 3, 6, 9, 12, and 15 days after inoculations were given. Severe bilateral atrophy of turbinates occurred in all toxin challenge-exposed pigs. Atrophy was more severe in the inoculated nasal cavity than that in the noninoculated side in 2 of the 10 pigs. Microscopic changes in turbinates of toxin challenge-exposed pigs were more severe in pigs killed at later dates. Dominant changes included degeneration and necrosis of osteoblasts, markedly accelerated osteoclastic osteolysis, replacement of the osseous core by a highly cellular mesenchymal stroma, and multifocal atrophy of submucosal glands. Seemingly, a protein toxin isolated from toxigenic type D strains of P multocida produced rapid atrophy of turbinates and may be a contributing factor in development of clinical progressive atrophic rhinitis in swine.     

Experimental Atrophic Rhinitis in Gnotobiotic Pigs

Twenty-nine caesarian derived colostrum deprived germfree pigs were reared in isolators in groups of three to four per isolator. At seven days of age each group was inoculated intranasally with one of four strains of Bordetella bronchiseptica (designated B, J, L and 55B), or Pseudomonas aeruginosa or a mucoid strain of Escherichia coli, all previously isolated from nasal mucus of pigs affected with clinical atrophic rhinitis. Another group was inoculated simultaneously with B. bronchiseptica B and Pasteurella multocida. The animals were observed for clinical signs of atrophic rhinitis and monitored bacteriologically at weekly intervals for seven weeks. Then they were bled for serology and killed and their respiratory organs examined for gross and histopathological lesions.

All of the pigs inoculated with the Bordetellae had inflammation of the nasal mucosa and developed positive serum antibody titers against all four of the Bordetella strains used in this study. Strain J caused sneezing and turbinate atrophy in three of four pigs. One of the three pigs inoculated with strain L died in ten days from bronchopneumonia and pericarditis and had turbinate atrophy. Strains B and B55 caused no turbinate atrophy, but two out of three pigs inoculated with both B. bronchiseptica B and P. multocida had turbinate atrophy. No nasal lesions were observed in the pigs inoculated with E. coli or P. aeruginosa or in the noninoculated germfree controls.

The results indicate a variation in the ability of different strains of B. bronchiseptica to cause turbinate atrophy in pigs and demonstrate that nasal infections by these organisms stimulate serum antibody response. Presence of P. multocida appears to increase the severity of the lesions. As the E. coli and Pseudomonas failed to produce atrophic rhinitis, they are probably of no significance as primary etiological agents in the atrophic rhinitis syndrome in swine.

     

Expression of the dermonecrotic toxin by Bordetella bronchiseptica is not necessary for predisposing to infection with toxigenic Pasteurella multocida

This experiment was designed to determine whether a Bordetella bronchiseptica mutant that does not produce dermonecrotic toxin (DNT) is still capable of predisposing pigs to infection with toxigenic Pasteurella multocida. Three groups of pigs were initially inoculated intranasally with a wild type B. bronchiseptica that produces DNT, an isogenic mutant of B. bronchiseptica that does not produce DNT, or PBS. All pigs were then challenged intranasally with a toxigenic strain of P. multocida 4 days later. P. multocida was recovered infrequently and in low numbers from pigs initially inoculated with PBS, and no turbinate atrophy was present in these pigs. P. multocida was isolated in similar numbers from the pigs initially inoculated with either the wild type or the DNT mutant of B. bronchiseptica, and turbinate atrophy of a similar magnitude was also seen in pigs from both of these groups. Thus, although the DNT has been shown to be responsible for much of the pathology seen during infection with B. bronchiseptica by itself, infection with non-DNT-producing strains can still predispose to secondary respiratory infections with P. multocida.     

Clinical and pathological effects of the dermonecrotic toxin of Bordetella bronchiseptica and Pasteurella multocida in specific-pathogen-free piglets

The role of dermonecrotic toxin (DNT) of Bordetella bronchiseptica and Pasteurella multocida, purified by repeated chromatography in Sephacryl S-200 gel, in the pathogenesis of atrophic rhinitis (AR) of swine was studied bacteriologically, clinically and pathologically. Two-week-old specific pathogen-free (SPF) piglets were parenterally treated with 30 micrograms of DNT 3 times at 2-day interval and 7-week-old piglets were treated with 15 micrograms of DNT twice a week for 5 weeks. In 2- to 3-week-old piglets, both B. bronchiseptica DNT and P. multocida DNT produced nasal turbinate lesions with similar severity, characterized by damage of the cilia, epithelial metaplasia, intensive proliferation of osteoblasts, regressive changes, and diffuse osteocytic osteolysis. In 7- to 12-week-old piglets, treatment with B. bronchiseptica DNT failed to produce progressive changes in the nasal turbinates. Histopathological examination revealed osteogenic processes and osteoid synthesis besides the proliferation of osteoblasts and mild osteocytic osteolysis. Moreover, severe gross pathological lesions developed in the stomach, liver, kidneys, and lymphoid organs. The piglets' appetite and body weight gain gradually decreased during the DNT treatment and in the last week when the toxic signs appeared. Treatment of 7- to 12-week-old piglets with P. multocida DNT resulted in progressive AR. Histopathologically, diffuse osteocytic osteolysis was observed in the nasal turbinates. Neither clinical signs nor pathological lesions of the visceral organs developed in these piglets. The authors emphasize that the DNT of B. bronchiseptica basically differs from that of P. multocida in biological properties, though there are certain similarities between the DNTs.     

Prevention and treatment of atrophic rhinitis in pigs with Getroxel, chlorquinaldol and oxytetracycline.

The sensitivity of ten Bordetella bronchiseptica and ten Pasteurella multocida strains, each isolated from cases of atrophic rhinitis (AR), was examined in tube dilution test. Getroxel, chlorquinaldol and oxytetracycline and the former two ones combined with trimethoprim inhibited the growth of both species in vitro. The minimum inhibitory and the minimum bactericidal concentration was less than 0.5 microgram/ml. When efficacy was tested in SPF in the group fed a combination of Getroxel, chlorquinaldol and oxytetracycline (60 mg, 240 mg and 360 mg/kg of feed, respectively), P. multocida disappeared from the nasal cavity by the end of a 30-day treatment. B. bronchiseptica was reisolated in low numbers from 2 out of 9 piglets. The daily body mass gain was by 7.9% higher and the feed conversion rate was by 19% better than in the control group. After slaughter, only mild signs of AR were seen in 3 out of 9 piglets treated with the above-mentioned drug combination, while in the control group severe lesions were observed in 8 out of 9 pigs. In treated commercial herds P. multocida disappeared from the nasal cavity of the piglets by the end of the treatment (42nd day of life), but the B. bronchiseptica strains could not be completely eliminated. Due to the treatment, mortality between 2 and 6 weeks of age decreased by 0.8-7.6%. Daily body mass gain was, on the average, 16.4% higher, the amount of feed needed for 1 kg body mass gain was by 15.3% lower and the duration of fattening was by 30.8 days shorter than in the control groups.     

An evaluation in pigs of Nobi-Vac AR and an experimental atrophic rhinitis vaccine containing P multocida DNT-toxoid and B bronchiseptica

The trial involved eight large white sows obtained from a closed experimental specific pathogen free herd. Four sows (two each for an experimental vaccine and for Nobi-Vac AR) were vaccinated twice (eight weeks and two weeks before parturition) with 2 ml of vaccine administered intramuscularly. Two unvaccinated sows were used as an infected control group and two unvaccinated sows served as an uninfected control group. Forty-six piglets (28 from vaccinated sows and 18 from unvaccinated sows) were challenged by intranasal instillation of Bordetella bronchiseptica at two days of age and Pasteurella multocida type D, dermonecrotic toxin at seven days of age. Among the infected control group some piglets died and there were clinical signs of pneumonia and severe turbinate atrophy. In the vaccinated groups the results showed that immunisation of the pregnant sows had provided a good level of antibodies, which were transmitted to their offspring. There was a significant reduction in the clinical signs and no lesions were observed in the group vaccinated with the experimental vaccine and only moderate atrophy of the turbinates in the Nobi-Vac AR group. B bronchiseptica and P multocida were never recovered from the lungs of the vaccinated groups and in the nasal cavities their frequency declined with age.     

Atrophic rhinitis in New Zealand white rabbits infected with Pasteurella multocida

Atrophic rhinitis was detected in New Zealand White rabbits when upper respiratory tract disease was evaluated during a vaccine field trial for the prevention of pasteurellosis. Of 52 adult rabbits euthanatized and necropsied, 26 (50%) had evidence of turbinate atrophy. Atrophy was detected in 77% of rabbits with Pasteurella multocida infection only, 71% of rabbits with concurrent P multocida and Bordetella bronchiseptica infections, and 6% of rabbits with B bronchiseptica infection only. Grossly, turbinate atrophy was characterized by a mild to severe loss or diminution in the maxilloturbinates. Histologically, turbinate bones were small and irregular in thickness and had numerous osteoclasts and osteoblasts. A neutrophilic exudate filled the nasal passages, and infiltrates of neutrophils and lymphocytes were detected in the mucosa and submucosa of the nasal turbinates. Rhinitis was significantly (P less than 0.001) associated with turbinate atrophy. Isolates of P multocida from rabbits with turbinate atrophy were serotype A:12.     

Effects of intranasal inoculation of porcine reproductive and respiratory syndrome virus, Bordetella bronchiseptica, or a combination of both organisms in pigs

OBJECTIVE: To examine effects of co-infection with porcine reproductive and respiratory syndrome virus (PRRSV) and Bordetella bronchiseptica in pigs. ANIMALS: Forty 3-week-old pigs. Procedure-30 pigs (10 pigs/group) were inoculated with PRRSV, B bronchiseptica, or both. Ten noninoculated pigs were control animals. RESULTS: Clinical signs, febrile response, and decreased weight gain were most severe in the group inoculated with both organisms. The PRRSV was isolated from all pigs in both groups inoculated with virus. All pigs in both groups that received PRRSV had gross and microscopic lesions consistent with interstitial pneumonia. Bordetella bronchiseptica was cultured from all pigs in both groups inoculated with that bacterium. Colonization of anatomic sites by B bronchiseptica was comparable between both groups. Pigs in the group that received only B bronchiseptica lacked gross or microscopic lung lesions, and B bronchiseptica was not isolated from lung tissue. In the group inoculated with B bronchiseptica and PRRSV, 3 of 5 pigs 10 days after inoculation and 5 of 5 pigs 21 days after inoculation had gross and microscopic lesions consistent with bacterial bronchopneumonia, and B bronchiseptica was isolated from the lungs of 7 of those 10 pigs. CONCLUSIONS AND CLINICAL RELEVANCE: Clinical disease was exacerbated in co-infected pigs, including an increased febrile response, decreased weight gain, and B bronchiseptica-induced pneumonia. Bordetella bronchiseptica and PRRSV may circulate in a herd and cause subclinical infections. Therefore, co-infection with these organisms may cause clinical respiratory tract disease and leave pigs more susceptible to subsequent infection with opportunistic bacteria.     

Immune responses in swine given lipid-conjugated pseudorabies viral antigens.

The immune response was compared in pigs given inactivated pseudorabies virus (PRV) antigens (with or without adjuvant) or PRV antigens covalently conjugated with a fatty acid (lauric acid) to enhance delayed-type hypersensitivity. The pigs were given 2 inoculations, 14 days apart, and were challenge exposed 28 days after the 1st inoculation. Pibs inoculated with PRV antigens, with or without adjuvant, had significant virus-neutralizing (VN) antibodies before challenge exposure, but the pigs inoculated with lipid-conjugated PRV antigens had no detectable VN antibodies, with the exception of 1 pig. All inoculated pigs were positive by the microimmunodiffusion test at postinoculation day 14 and remained positive throughout the experiment. The inoculated pigs had delayed-type hypersensitivity reactions when skin tested a postinoculation day 25; the pigs inoculated with lipid-conjugated PRV antigens had a more pronounced reaction. Inoculated pigs had mild respiratory signs on the 3rd through the 6th days after challange exposure, with no observable difference in severity between the inoculated groups. The control pigs had acute signs of PRV, and 3 or 4 pigs died 5 to 8 days after challenge exposure. The average VN titers of the different inoculated groups of pigs were nearly equal 2 weeks after challenge exposure. Results indicated that both humoral antibodies and cell-mediated immunity have a role in PRV infections in swine.     

Vaccine efficacy for reducing turbinate atrophy and improving growth rate in piggeries with endemic atrophic rhinitis

Two vaccines, based on formalin-killed whole cells of toxigenic Pasteurella multocida type D and Bordetella bronchiseptica combined with a partially toxoided cell extract of P multocida, were prepared with Freund's incomplete adjuvant (vaccine 1) or by alum precipitation (vaccine 2). Each was tested for safety and efficacy in reducing the severity of nasal turbinate atrophy and improving the growth rate of pigs in three Western Australian commercial piggeries with endemic atrophic rhinitis. In safety experiments with vaccine 1, no adverse clinical effects were observed in vaccinated sows or their progeny. Piglets receiving vaccine 2 showed no injection site abnormalities, pyrexia or turbinate atrophy. In field trials, vaccine 1 significantly reduced the prevalence of moderate to severe nasal turbinate atrophy (Done score 3 to 5) when used in two piggeries (A and B). Progeny from vaccinated sows in piggery B also grew significantly faster than controls. When vaccine 2 was used in piggery A at a later date and in another piggery (C), growth rate was not improved in either piggery and the prevalence of moderate to severe turbinate atrophy was reduced only in piggery C.     

Protection against progressive atrophic rhinitis by vaccination with Pasteurella multocida toxin purified by monoclonal antibodies

Pasteurella multocida toxin was purified by affinity chromatography and inactivated by treatment with formaldehyde before use as a single component vaccine against progressive atrophic rhinitis in pigs. Twenty pregnant gilts which were vaccinated twice before farrowing with either low or high doses of the purified toxoid, developed dose-dependent positive serum and colostrum titres to the toxin and, unlike the progeny of 10 untreated control gilts, the offspring of the vaccinated gilts also had serum titres. These titres could be measured in blood samples taken for more than eight weeks from birth for most pigs born to gilts vaccinated with low doses and more than 12 weeks for pigs born to gilts vaccinated with high doses of the vaccine. All the piglets were inoculated intranasally with Bordetella bronchiseptica and toxigenic P multocida. The clinical and post mortem examinations of snouts revealed a significant reduction in the frequency and degree of conchal atrophy in the two groups of pigs from the vaccinated gilts compared with the pigs from control gilts. Clinically 90 per cent of the snouts of pigs born to vaccinated gilts appeared normal whereas only 28 per cent of the snouts of control pigs were not shortened or deviated at eight weeks of age. At slaughter 11 per cent of the pigs born to vaccinated gilts and 81 per cent of the control pigs had severe turbinate atrophy.(ABSTRACT TRUNCATED AT 250 WORDS)     

Induced atrophic rhinitis in rats

Infections with Bordetella bronchiseptica and Pasteurella multocida were inducted in newborn specific-pathogen-free rats. Turbinate atrophy was quantified by measuring the length of the osseous core of the ventral turbinates. Bordetella bronchiseptica readily colonized the nasal cavity. Inoculated rats developed serum agglutinating antibodies to B bronchiseptica. Turbinate atrophy, correlating with a severe inflammatory reaction, was observed after dual inoculation with B bronchiseptica or after a single inoculation when the inoculum contained relatively large numbers of B bronchiseptica. Pasteurella multocida only rarely colonized the nasal cavity, even after prior instillation of weak acetic acid solution or B bronchiseptica.