Turbinate Atrophy Research Articles

Effect of ovalbumin aerosol exposure on colonization of the porcine upper airway by Pasteurella multocida and effect of colonization on subsequent immune function.

Seventy-three piglets were weaned at 1 week of age, randomly assigned to 10 groups (A to J), accommodated in stainless steel exposure chambers, and exposed continuously to a controlled environment containing aerosolized ovalbumin. The concentrations of ovalbumin dust were as follows (milligrams per cubic meter): A and F, 16.6; B and G, 8.4; C and H, 4.2; D and I, 2.1; E and J, 0. At weekly intervals, the pigs were bled via venipuncture and anesthetized for nasal lavage and tonsilar biopsies performed for subsequent bacteriologic analysis. At 2 weeks of age, the pigs in groups A to E were challenged with toxigenic Pasteurella multocida (10(8) CFU pig(-1)), and at 6 weeks of age, the pigs were euthanatized. At postmortem, the extent of turbinate atrophy was assessed on the snout sections by using a morphometric index. Exposure to aerial ovalbumin resulted in a dose-dependent increase in serum antiovalbumin immunoglobulin G (IgG; P < 0.001) and serum antiovalbumin IgA (P < 0.001). Exposure also caused a significant increase in the numbers of P. multocida organisms isolated from the upper respiratory tract (P < 0.001) and a corresponding increase in turbinate atrophy, as judged by the morphometric index (P < 0.001). Concurrent challenge with P. multocida and ovalbumin resulted in a significant decrease in both the IgG and IgA responses to ovalbumin (P < 0.001). These results show that ovalbumin exposure increases pig susceptibility to P. multocida colonization and that toxigenic P. multocida modifies the serum IgG and IgA responses to ovalbumin in the pig. Both of these effects may enhance the virulence of this respiratory pathogen and so influence the pathogenesis of atrophic rhinitis in pigs.

Effects of ammonia inhalation and acetic acid pretreatment on colonization kinetics of toxigenic Pasteurella multocida within upper respiratory tracts of swine.

Pigs reared in intensive production systems are continuously exposed to ammonia released by the microbial degradation of their excrement. Exposure to this gas has been shown to increase the severity of the disease progressive atrophic rhinitis by facilitating colonization of the pig's upper respiratory tract by Pasteurella multocida. The etiological mechanism responsible for this synergy was investigated by studying the colonization kinetics of P. multocida enhanced by ammonia and comparing them with those evoked by an established disease model. Three-week-old Large White piglets were weaned and allocated to five experimental groups (groups A to E). Pigs in groups A and B were exposed continuously to ammonia at 20 ppm for the first 2 weeks of the study. Pigs in group C were pretreated with 0.5 ml of 1% acetic acid per nostril on days -2 and -1 of the study. On day 0 all the pigs in groups A, C, and D were inoculated with 1.4 x 10(8) toxigenic P. multocida organisms given by the intranasal route. The kinetics of P. multocida colonization were established by testing samples obtained at weekly intervals throughout the study. The study was terminated on day 37, and the extent of turbinate atrophy was determined by using a morphometric index. The results of the study showed that exposure to aerial ammonia for a limited period had a marked effect on the colonization of toxigenic P. multocida in the nasal cavities of pigs, which resulted in the almost total exclusion of commensal flora. In contrast, ammonia had only a limited effect on P. multocida colonization at the tonsil. The exacerbation of P. multocida colonization by ammonia was restricted to the period of ammonia exposure, and the number of P. multocida organisms colonizing the upper respiratory tract declined rapidly upon the cessation of exposure to ammonia. During the exposure period, the ammonia levels in mucus recovered from the nasal cavity and tonsil were found to be 7- and 3.5-fold higher, respectively, than the levels in samples taken from unexposed controls. Acetic acid pretreatment also induced marked colonization of the nasal cavity which, in contrast to that induced by ammonia, persisted throughout the time course of the study. Furthermore, acetic acid pretreatment induced marked but transient colonization of the tonsil. These findings suggest that the synergistic effect of ammonia acts through an etiological mechanism different from that evoked by acetic acid pretreatment. A strong correlation was found between the numbers of P. multocida organisms isolated from the nasal cavity and the severity of clinical lesions, as determined by using a morphometric index. The data presented in the paper highlight the potential importance of ammonia as an exacerbating factor in respiratory disease of intensively reared livestock.

EFFECT OF CHRONIC EXPOSURE TO GASEOUS AMMONIA ON THE NASAL TURBINATES OF GNOTOBIOTIC PIGS

Pigs reared in and stock persons working in intensive production systems are continuously exposed to ammonia released by microbial degradation of animal excrement. Experimental studies have shown that exposure to this gas, at concentrations comparable to those encountered in buildings used for the intensive rearing of swine, increases the severity of the clinical disease progressive atrophic rhinitis in pigs by facilitating colonization of the upper respiratory tract by toxigenic Pasteurella multocida. During the course of these studies it was observed that mild turbinate atrophy also occurred in pigs from control groups exposed to ammonia but maintained free from P. multocida and Bordetella bronchiseptica. To determine whether exposure to ammonia is detrimental to the normal anatomical development of the mammalian nasal cavity, a study was conducted using gnotobiotic piglets. Twenty-one gnotobiotic piglets were derived from two sows by hysterectomy. Each litter was split into two groups, and the four groups were accommodated separately in sterile positive-pressure isolators supplied with high-efficiency particulate air (HEPA) filtered air. From 1 wk of age onward the air in the isolators housing one of the groups from each litter was modified by the addition of ammonia at a concentration of 9.1 and 15.7 ppm. The air supply to the isolators housing the littermate groups was not modified. At 6 wk of age all the pigs were euthanatized. The effect of ammonia exposure on the morphology of the nasal cavity of the pig was assessed by image analysis of a cross section of the pig's snout. Pigs exposed to ammonia were found to have a mild but statistically significant level of turbinate atrophy when compared to nonexposed lit termates. Histological examination revealed that prolonged ammonia exposure evoked changes to the mucous membranes lining the nasal cavity, characterized by epithelial hyperplasia with micro-abscess formation, goblet-cell hypoplasia, and inflammatory cell infiltration. Mild degenerative changes within the bony core of the ventral turbinate were also apparent, with a decline in the population of osteoblasts and simultaneous osteoclast proliferation. Group analysis revealed a correlation between the severity of turbinate atrophy and the increase in the number of osteoclasts per unit area of bony core (p<.05). These findings could explain why mild turbinate atrophy is seen on some pig units deemed free from pathogenic bacteria associated with the clinical disease atrophic rhinitis.

Effects of Pasteurella multocida toxin on porcine bone marrow cell differentiation into osteoclasts and osteoblasts.

The effect of Pasteurella multocida toxin (PMT) on porcine osteoclast and osteoblast differentiation was studied using in vitro cell culture systems. When grown in the presence of Vitamin D3, isolated porcine bone marrow cells formed multinucleated cells with features characteristic of osteoclasts. Exposure of bone marrow cells to Vitamin D3 and PMT during growth resulted in formation of increased numbers and earlier appearance of osteoclasts compared to controls. Ultrafiltered medium form PMT-treated cells likewise increased osteoclast numbers, suggesting that a soluble mediator may be involved in the action of PMT. When cell cultures were treated with fluorescein-labeled PMT, fluorescence was found within the cytoplasm of small, round cells that did not resemble either osteoclasts or osteoclastic precursor cells. Cultures of porcine bone marrow cells exposed to dexamethasone, ascorbic acid, and beta-glycerophosphate developed into osteoblastic cells that formed multilayered, mineralized nodules. Exposure of osteoblastic cultures to low concentration of PMT resulted in retarded cell growth, formation of decreased numbers of nodules and minimal to no mineralization in the nodules; higher concentration of PMT resulted in increased cellular debris and poor growth of cells, with no nodule formation. These findings suggest that PMT may induce turbinate atrophy in pigs by increasing osteoclast numbers and inhibiting osteoblastic bone formation. The effect of PMT on osteoclastic differentiation and growth may not be due to a direct effect on preosteoclastic cells, but rather due to alterations in the soluble mediator secretion by marrow stromal cells.

Effect of Bordetella bronchiseptica and serotype D Pasteurella multocida bacterin-toxoid on the occurrence of atrophic rhinitis after experimental infection with B. bronchiseptica and toxigenic type AP. multocida.

In efficacy tests, 7 primary specific-pathogen-free piglets vaccinated with the Bordetella bronchiseptica and type D Pasteurella multocida bacterin-toxoid were challenged with B. bronchiseptica and type A P. multocida. Severe or moderate nasal turbinate atrophy was produced in the non-vaccinated pigs, whereas, only one of the 4 pigs in the vaccinated group had slight turbinate atrophy. Other immune sera against crude toxin of P. multocida type A or D were cross neutralized. The results of the present study show that the P. multocida serotype D bacterin-toxoid is effective against atrophic rhinitis caused by toxigenic P. multocida serotype A as well as toxigenic P. multocida serotype D.

A porcine model for the evaluation of virulence of Bordetella bronchiseptica

Studies of virulence factors of Bordetella bronchiseptica require a suitable system. Such a system was devised in colostrum-deprived, caesarean-derived pigs, aged 7 d. In two different experiments, pigs (n = 11) were inoculated intranasally with 10(6) colony-forming units of the virulent strain 4609. In the same way, further pigs (n = 11) were inoculated with a strain (B133) of unknown virulence. No significant differences between 4609 and B133 colonization were seen. However, colonization of the turbinates was significantly higher than that of the trachea, lung and tonsil, and a significantly higher degree of colonization was present at 11 d post-inoculation (PI) than at 15 days. Moderate turbinate atrophy was present by 11 d PI, and peribronchiolar fibrosis was present at 15 days. Immunocytochemical methods showed that all pigs had bacterial antigen in the ciliated cells of the turbinates and trachea, and in the lung; some pigs also had antigen in the bronchi. Bacterial antigen was present in some bronchioles and within the cytoplasm of pulmonary macrophages and neutrophils. This model should prove useful for comparing strains of B. bronchiseptica and isogenic mutants deficient in putative virulence factors.

Synergistic role of gaseous ammonia in etiology of Pasteurella multocida-induced atrophic rhinitis in swine.

One-week-old Large White piglets were weaned and allocated to 14 experimental groups, each composed of five animals. Each group was housed in a separate Rochester exposure chamber and exposed continuously to gaseous ammonia at either 0, 5, 10, 15, 25, 35, or 50 ppm (two groups per exposure level). One week after ammonia exposure commenced, the pigs from one group at each exposure level were inoculated intranasally with 9 x 10(7) CFU of Pasteurella multocida type D. After a further 4 weeks of exposure, all the pigs were euthanized and the extent of turbinate degeneration was assessed by using a morphometric index (J.T. Done, D. H. Upcott, D. C. Frewin, and C. N. Hebert, Vet. Rec. 114:33-35, 1984) and a subjective scoring system (Ministry of Agriculture, Fisheries and Food, Atrophic Rhinitis: a System of Snout Grading, 1978). Exposure to ammonia at a concentration of 5 ppm or greater resulted in a significant increase in the severity of turbinate atrophy induced by P. multocida compared with that occurring in pigs kept in 0 ppm of ammonia. This effect was maximal at 10 ppm but decreased progressively at concentrations above 25 ppm. Regression analysis revealed a significant relationship between the severity of turbinate degeneration and the number of P. multocida organisms isolated from the nasal epithelium at the end of the experiment (R2 = 0.86). These findings suggest that exposure to ammonia facilitates the growth and/or survival of P. multocida within the upper respiratory tract of the pig, thereby contributing to the severity of the clinical disease atrophic rhinitis. Furthermore, exposure of pigs to ammonia at 10 ppm or greater, in the absence of either P. multocida or Bordetella bronchiseptica, induced a mild but statistically significant degree of turbinate atrophy. The findings of this study demonstrate that exposure to ammonia, at concentrations within the range encountered commonly in commercial piggeries, contributes to the severity of clinical lesions associated with atrophic rhinitis.

Agreement among veterinarians evaluating gross lesions of lungs, livers, and nasal turbinates of pigs

Objective To evaluate agreement between trained veterinarians and a reference inspector when recording gross lesions of lungs, livers, and nasal turbinates of pigs. Design Prospective study. Sample Population 10 veterinarians in workshop 1 and 11 veterinarians in workshop 2. Procedure Analysis of data obtained from 2 workshops in which veterinarians evaluated fresh tissues (30 lungs and 30 livers) and 100 slides of nasal turbinates previously evaluated by the reference inspector. Veterinarians independently recorded observations of gross lesions. Agreement was evaluated by percentage agreement, kappa or weighted kappa, and sensitivity and specificity, where relevant. Results Agreement between veterinarians and the reference inspector was excellent for detecting consolidation of lung lobes typical of enzootic pneumonia (κ = 0.81 and 0.87 for workshops 1 and 2, respectively) and white spots on livers (κ = 0.76 and 0.78). Estimates of the extent of consolidation as a proportion of lung volume also agreed closely with reference values. Agreement was closer for veterinarians who had undergone repeated training and evaluation. Agreement was good for detecting nasal turbinate atrophy (weighted κ = 0.63 and 0.68) and was poorest for detecting lesions of pleuritis (κ = 0.39 and 0.44). Clinical Implications For most of the lesions evaluated, acceptable levels of agreement with reference scores were achieved after training of veterinarians to use standardized methods to record gross lesions. Standardization of veterinarians’ recordings of gross lesions should improve the reliability and usefulness of data collected by inspection of slaughtered pigs. (J Am Vet Med Assoc 1996;209:823–826)

A 90-Day Chloroform Inhalation Study in F-344 Rats: Profile of Toxicity and Relevance to Cancer Studies

Chloroform acts via a nongenotoxic–cytotoxic mode of action to produce cancer if given in doses and at dose rates sufficiently high to produce organ-specific toxicity. In a recent study, chloroform failed to induce cancer in male or female F-344 rats when administered by inhalation for 2 years at 90 ppm, 5 days/week. The present study was undertaken to define the concentration–response curves for chloroform-induced lesions and regenerative cell proliferation in the F-344 rat when exposed by inhalation and to correlate those patterns of toxicity with the results from the inhalation cancer bioassay. Male and female F-344 rats were exposed to airborne concentrations of 0, 2, 10, 30, 90, or 300 ppm chloroform 6 hr/day, 7 days/week for 4 days or 3, 6, or 13 weeks. Additional treatment groups were exposed 5 days/week for 13 weeks or were exposed for 6 weeks and held until Week 13. Bromodeoxyuridine was administered via osmotic pumps implanted 3.5 days prior to necropsy and the labeling index (LI, percentage of nuclei in S-phase) was evaluated immunohistochemically. A full-screen necropsy identified the kidney, liver, and nasal passages as the only target organs. This study confirmed that 300 ppm is extremely toxic and would be inappropriate for longer-term cancer studies. The primary target in the kidney was the epithelial cells of the proximal tubules of the cortex, with significantly elevated increases in the LI at concentrations of 30 ppm and above. However, only a marginal increase in the renal LI in the males was seen after exposures of 90 ppm, 5 days/week. Chloroform induced hepatic lesions in the midzonal and centrilobular regions with increases in the LI throughout the liver, but only at 300 ppm exposures. An additional liver lesion seen only at the highly hepatotoxic concentration of 300 ppm was numerous intestinal crypt-like ducts surrounded by dense connective tissue. Enhanced bone growth and hypercellularity in the lamina propria of the ethmoid turbinates of the nose occurred at the early time points at concentrations of 10 ppm and above. At 90 days there was a generalized atrophy of the ethmoid turbinates at concentrations of 2 ppm and above. Cytolethality and regenerative cell proliferation are necessary but not always sufficient to induce cancer because of tissue, sex, and species differences in susceptibility. A combination of a lack of direct genotoxic activity by chloroform, only a marginal induction of cell proliferation in the male rat kidney, and lower tissue-specific susceptibility in the female rat is apparently responsible for the reported lack of chloroform-induced cancer in a long-term inhalation bioassay with F-344 rats.

Attitudes of veterinarians to a standardized slaughter-monitoring program for pigs

Objective To determine attitudes of participating veterinarians toward a standardized slaughter-monitoring program for swine. Design Survey by mail questionnaire. Sample Population 30 of 35 veterinarians in Minnesota who had participated in the program in 1993. Procedure Survey was conducted regarding a slaughter-monitoring program. Respondents answered questions related to professional experience, use of slaughter inspections, methods, advantages and disadvantages of the program, effects on clients and business, labor requirements, referral of inspections, confidence in identifying lesions, and usefulness of reports for on-farm decision making. Results 27 respondents expressed overall satisfaction with the program. Perceived advantages of the program included use of standardized methods, quality of reports, inspection of more types of lesions, and accumulation of data. Disadvantages predominantly related to increased time commitments for veterinarians. Data considered most useful for on-farm decision making were white spots on livers, nasal turbinate atrophy, and lesions indicative of papular dermatitis and enzootic pneumonia. Respondents perceived positive effects of participating in this program In the areas of recruitment of clients, frequency of visits to clients, recommendations made to clients, satisfaction of client needs, and generation of revenue. Clinical Implications A standardized slaughter-monitoring program designed to provide improved information from slaughter inspections may be beneficial to the businesses of participating veterinarians. (J Am Vet Med Assoc 1996;209:123–126)

Enhancement of respiratory immunity to Pasteurella multocida by cholera toxin in rabbits.

Cholera toxin (CT) is a potent adjuvant for the mucosal immune system. The purpose of this study was to determine if coadministration of CT with a potassium thiocyanate extract of Pasteurella multocida (PTE) leads to enhanced anti-PTE antibody activity and increased protection of rabbits against infection with P. multocida and associated disease. Groups of rabbits were immunized intranasally on days 0, 7, and 14, with phosphate buffered saline (PBS), 200 micrograms of CT, 1.0 mg of PTE, or 1.0 mg PTE with 200 micrograms CT. Nasal lavage and serum samples were collected over 28 days after initial immunization and evaluated by ELISA for specific antibody directed against PTE. Marked increases in serum (IgG) and nasal lavage (IgA) anti-PTE antibody activity were found beginning after day 14 in rabbits immunized with PTE. Rabbits immunized with PTE and CT demonstrated further increases in this activity. Tracheobronchial lavage samples collected at the time of necropsy demonstrated a significant level of anti-PTE IgA activity in animals immunized with PTE, and coadministration with CT stimulated a further significant increase in this activity. Groups of similarly immunized rabbits were challenged 16 days after initial immunization with 5 x 10(7) CFUs of P. multocida. Nasal lavage samples were cultured for P. multocida over the next 10 days. Rabbits were euthanized within 10 days after challenge, tissues cultured for P. multocida, and histopathologic lesion severity graded using a numeric scale. Rabbits immunized with PTE survived longer, had less severe lesions of the lungs, pleura, and liver, and fewer P. multocida CFUs cultured from samples than PBS or CT controls. Coadministration of CT led to further reductions in lesion severity of those tissues and numbers of P. multocida CFUs cultured from samples. Increased nasal turbinate atrophy of rabbits immunized with PTE with or without CT was associated with increased mean survival time. In summary, coadministration of CT with PTE enhanced protective immunity to P. multocida disease and infection in rabbits.

野外における&lt;I&gt;Bordetella bronchiseptica/Pasteurella multocida&lt;/I&gt;D型混合不活化ワクチンの豚萎縮性鼻炎に対する効果

Effects ofBordetella bronchiseptica and Pasteurella multocidatype D vaccine on atrophic rhinitis (AR) was evaluated in the field. Thirty two pregnant sows were vaccinated twice with 2ml prior to farrowing and their 300 piglets were vaccinated with 1ml once or twice. In herd A, turbinate atrophy was seen in 16.3% and 12.1% of piglets vaccinated with one and two doses, respectively, while in 52.8% of the control group. In herd B, showing obvious clinical sings of AR and turbinate atrophy (70%) in the control group, the incidence of clinical signs and turbinate atrophy were significantly lower in the both vaccinated groups. The mean ages of slaughtering were 8.9 and 11.2 days shorter in the vaccinated groups with one and two doses, respectively.

Virulence of capsulated and noncapsulated isolates of Pasteurella multocida and their adherence to porcine respiratory tract cells and mucus.

The virulence and the adherence to porcine respiratory tract cells and mucus of three toxigenic, capsular type D Pasteurella multocida isolates and their noncapsulated variants were evaluated in the present study. Loss of capsule by P. multocida, verified by transmission electron microscopy after polycationic ferritin labeling, was associated with a massive reduction in virulence of the organisms in mice. Specific-pathogen-free piglets inoculated intranasally with one of the capsulated isolates or its noncapsulated variant developed turbinate lesions characterized by bone resorption and by an inflammation of the mucosa associated with hyperplasia and squamous metaplasia of the epithelium. Infection with the capsulated isolate led to more severe lesions and atrophy of turbinates. The interactions of these P. multocida isolates with porcine respiratory tract cells and mucus were studied in vitro. The presence of capsule resulted in a decrease in binding of respiratory tract mucus were studied in vitro. The presence of capsule resulted in a decrease in binding of respiratory tract mucus to P. multocida isolates as determined by a dot blot assay. The presence of capsule also resulted in a significant decrease in adherence to porcine tracheal rings maintained in culture. The capsule seemed to mask outer membrane components which are involved in adherence. One of these components might be lipopolysaccharide since purified lipopolysaccharide bound respiratory tract mucus and blocked adherence of this microorganism to porcine tracheal rings. Our data indicate that capsular material does not seem to be involved in adherence of P. multocida to respiratory tract cells and mucus, but capsulated isolates are more virulent in mice and also in piglets.

Toxin production by Pasteurella multocida isolated from rabbits with atrophic rhinitis

Summary Naturally acquired turbinate atrophy in rabbits was associated with Pasteurella multocida infection. Several in vitro and in vivo studies were conducted to document toxin production from P multocida isolates and to determine the relation of toxin to atrophic rhinitis in rabbits. Ten isolates of P multocida serotype A:12 were obtained from adult New Zealand White rabbits with noninduced atrophic rhinitis. Specific-pathogen-free rabbits inoculated intranasally with isolates of P multocida developed rhinitis and turbinate atrophy. However, inoculation with filtrates of the same bacteria failed to induce turbinate atrophy. Cytotoxicity was observed in assays, using bovine embryonic turbinate cell cultures with extracts of P multocida, but not in agar overlay cytotoxicity assays, using bovine embryonic turbinate, bovine embryonic lung, or Vero cell cultures, or in a sandwich elisa, using monoclonal antibodies to purified P multocida toxin. Thus, turbinate atrophy was experimentally reproduced in rabbits with isolates of P multocida, but toxin was only detected in vitro by cell culture assay of P multocida extracts.

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.

Protective effect by cell-free antigen obtained from culture supernatant of phase I Bordetella bronchiseptica.

The cell-free antigen (CFA), with highly hemagglutination activity, obtained from the culture supernatant of Bordetella bronchiseptica was compounded with oil adjuvant to make a component vaccine (CFAV). In the immunization trial in mice, the offsprings whose mothers were immunized with CFAV escaped from death when challenged intrapleurally with virulent strain of B. bronchiseptica. The protective indices (difference of LD50 dose of the challenge strain between immunized and control groups) of the offsprings from CFAV-immunized mothers were over 3.0 in common logarithm value. Moreover, about 90% of the offsprings from CFAV-immunized mothers were negative in nasal turbinate atrophy, while over 80% of them from non-immunized mothers showed obvious turbinate atrophy when challenged intranasally with virulent strain. On the one hand, remarkable differences in the number of bacteria recovered from nostrils were observed between both test groups. It was concluded that CFAV is a very effective vaccine against B. bronchiseptica infection in animals.

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.

Experimental model of atrophic rhinitis in gnotobiotic pigs

To study the pathogenesis of atrophic rhinitis, gnotobiotic pigs (n = 6) were inoculated intranasally with a sterile sonicate of a toxigenic strain of Bordetella bronchiseptica (0.16 mg of protein per ml) at 5 days of age, and they were then inoculated intranasally with 1 ml (5,250 CFU/ml) of a live, toxigenic strain of Pasteurella multocida at 7 days of age. Pigs were necropsied at 2, 5, 9, 14, 21, and 28 days postinoculation; those pigs necropsied after 5 days had developed turbinate atrophy. Other gnotobiotic pigs received the following inoculation protocols: (i) a sterile sonicate of a nontoxigenic strain of B. bronchiseptica (0.2 mg of protein per ml), followed by toxigenic P. multocida (n = 4); (ii) toxigenic P. multocida alone (n = 7); (iii) diluent (sterile tryptose broth) (n = 2); (iv) the sterile sonicate of toxigenic B. bronchiseptica alone (n = 2); or (v) the sterile sonicate of a nontoxigenic strain of B. bronchiseptica alone (n = 2). Turbinate atrophy did not occur in the latter groups except for one pig inoculated with only toxigenic P. multocida. These studies show that turbinate atrophy occurs in pigs given the toxigenic B. bronchiseptica sonicate and then given live, toxigenic P. multocida. This experimental regimen is a useful model for (i) studying the pathogenesis of atrophic rhinitis and (ii) testing vaccine strategies.

Induction of pneumonia in rabbits by use of a purified protein toxin from Pasteurella multocida

SUMMARY Heat-labile toxin from a cell sonicate of a virulent typeD strain of Pasteurella multocida was purified by ammonium sulfate precipitation followed by ion exchange chromatography, gel filtration chromatography, and Polyacrylamide gel electrophoresis. Toxic activity was assayed during toxin purification by cytopathic effect in Vero or bovine embryonic lung cell cultures. Toxicity for cells correlated with dermonecrosis in guinea pig skin. Toxicity was accounted for by a single protein with a molecular weight of 149,000, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Rabbits were inoculated intranasally with purified toxin to determine whether toxin had a role in the induction of pneumonia in rabbits infected with P multocida. Pneumonia, pleuritis, acute hepatic necrosis, and splenic lymphoid atrophy were found in 4 of 5 rabbits. One of 5 rabbits had bilateral turbinate atrophy. Western blotting with monoclonal antibodies to toxin from a P multocida isolate causing atrophic rhinitis in pigs revealed the toxin that induces pleuritis and pneumonia in rabbits to be the same or a closely related toxin.

Reproduction of Turbinate Atrophy in Pigs by Intranasal Consecutive-Day Inoculation with Suspensions of a Toxigenic Serotype D Strain of Pasteurella multocida

Reproduction of Turbinate Atrophy in Pigs by Intranasal Consecutive-Day Inoculation with Suspensions of a Toxigenic Serotype D Strain of Pasteurella multocida