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.     

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.     

Evaluation of an atrophic rhinitis vaccine under controlled conditions.

A vaccine containing inactivated cultures of Bordetella bronchiseptica, toxigenic Pasteurella multocida type D and dermonecrotic P multocida type D toxoid in an oil-in-water adjuvant was given to seven sows, with seven others acting as controls. Half the piglets in each litter were exposed intranasally when four days old to B bronchiseptica and when eight days old to toxigenic P multocida type D. There was considerably less sneezing in the litters of the vaccinated sows and when the piglets were 10 weeks old, only 18 per cent had deformed snouts compared with 74 per cent in the litters of the control sows. The average liveweight gain of the piglets born to vaccinated sows was significantly better (P less than 0.05) between two and 10 weeks of age than that of the piglets born to unvaccinated sows, although there were no significant lower respiratory tract lesions in either group. The conchal atrophy scores were significantly lower (P less than 0.001) in the piglets from the vaccinated sows and were negatively correlated (r = -0.37) with increasing liveweight gain. In the liters of the vaccinated sows, P multocida was not isolated from the nasal passages of the in-contact piglets and from only 7 per cent of those deliberately exposed compared with 65 per cent and 79 per cent, respectively, in the litters of the control sows. P multocida was isolated post mortem from the tonsils of 23 per cent of the piglets of vaccinated sows and from 87 per cent of those from unvaccinated sows.     

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.     

Protection of piglets against atrophic rhinitis by vaccinating the sow with a vaccine against Pasteurella multocida and Bordetella bronchiseptica

The efficacy of a new vaccine against atrophic rhinitis in pigs was tested in the Netherlands and Denmark. The vaccine contained protein dO (a truncated Pasteurella multocida toxin which is immunogenic and non-toxic), inactivated Bordetella bronchiseptica whole cells, and an adjuvant. The sows were either vaccinated intramuscularly with 2 ml of the vaccine at six to eight and two to four weeks before expected farrowing or left unvaccinated as controls. All the piglets were challenged intranasally with B bronchiseptica when three to seven days old and with P multocida three to four days later. Pigs born to the vaccinated sows performed significantly better than pigs born to the control sows when judged on growth, average daily weight gain and snout scores. The challenge organisms were reisolated more frequently from the control pigs than from the pigs in the vaccinated group. The vaccinated sows and their progeny developed high titres of antibodies against B bronchiseptica and P multocida toxin.     

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 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.     

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)     

Vaccination against progressive atrophic rhinitis with a recombinant Pasteurella multocida toxin derivative.

Vaccination against progressive atrophic rhinitis using a purified recombinant derivative of the Pasteurella multocida toxin (PMT), was carried out. Ten pregnant gilts were vaccinated twice with the nontoxic derivative (dO) which apart from a lack of 121 amino acids had an amino acid sequence identical to PMT, while seven gilts were vaccinated with a purified, formaldehyde treated, native PMT and ten gilts served as non-vaccinated controls. The resulting piglets were inoculated intranasally with Bordetella bronchiseptica and toxigenic P. multocida. Among piglets from the nonvaccinated gilts all except one developed clinical atrophic rhinitis and 90% developed severe turbinate atrophy while only a few pigs in the vaccinated groups developed clinical or pathological signs of disease. Gilt colostra from the two vaccinated groups had similar mean anti-PMT titers and the mean titers in the offspring's sera from these groups were nearly identical throughout the study. No pigs born from unvaccinated gilts were seropositive until 8 wk of age (7 wk post-challenge) but 23% became seropositive at slaughter. The infection rate with toxigenic P. multocida in piglets and the total number of P. multocida colonies cultured from nasal swabs were significantly reduced at 5 wk and 8 wk of age in the vaccinated groups, when compared to controls. There was a significantly improved weight gain (greater than 9%) from birth to slaughter in offspring from vaccinated gilts. No significant differences in feed conversion rate or % lean meat were observed among the groups. The study showed the excellent immunoprotective properties of the nontoxic derivative of the PMT molecule.     

Vaccine potential of an attenuated Pasteurella multocida that expresses only the N-terminal truncated fragment of P. multocida toxin in pigs

Previously we described the development of an attenuated Pasteurella multocida mutant that expresses only the N-terminal truncated fragment of P. multocida toxin (N-PMT) and its protective effects in a mouse model. This paper details our evaluation of the vaccine potential of this mutant strain in pigs. Pigs vaccinated with the mutant showed significantly higher rates of antibody induction and lower nasal conchal (turbinate) scores for atrophic rhinitis than controls, which suggests that this mutant strain may be a good candidate for a live attenuated vaccine.     

Epidemiological studies of Brachyspira pilosicoli in two Australian piggeries

The epidemiology of infection with the intestinal spirochaete Brachyspira pilosicoli within pig herds is incompletely understood. To investigate this further, cross-sectional and cohort studies were undertaken on two piggeries. Faeces were subjected to selective culture, and DNA was extracted from growth on the primary media and amplified by polymerase chain reaction (PCR). On one farm, samples from other animal species and the environment were also examined. Isolates were subjected to multilocus enzyme electrophoresis (MLEE) and pulsed field gel electrophoresis (PFGE). The prevalence on farm A (>2000 sows) was 2.4% (95% confidence interval (CI): 0.3, 4.4%). Infection was largely confined to grower/finisher pigs. The six isolates of B. pilosicoli recovered belonged to a single MLEE electrophoretic type (ET) and a single PFGE type. On piggery B, an 80-sow unit located on a research farm, the prevalence amongst growers and finishers was 12.2% (95% CI: 4.7, 19.6%). There was also evidence that weaners were being infected. Ten isolates obtained were genetically heterogeneous, being divided into six ETs and seven PFGE types. One of four isolates in one ET had an identical PFGE type to those on piggery A, and may have been introduced to piggery B in stock from piggery A. On farm B, B. pilosicoli was also detected by PCR in chickens, effluent pond water and wild ducks on the pond. An isolate from the pond belonged to the same ET as one from a pig, whereas the duck isolates were distinct. This study demonstrates the complex epidemiology of B. pilosicoli infections in piggeries.     

Lesions of transmissible gastroenteritis virus infection in experimentally inoculated pigs suckling immunized sows

Intestinal lesions of transmissible gastroenteritis (TGE) virus infection in conventionally reared pigs suckling either nonvaccinated, vaccinated, or previously infected sows were studied by scanning electron microscopy, light microscopy, and immunofluorescent microscopy for TGE viral antigen. Pigs were inoculated with virulent TGE virus when they were 5 or 21 days old and were euthanatized shortly after the onset of diarrhea or 96 hours after inoculation if no diarrhea developed. Pigs inoculated when they were either 5 or 21 days old and suckling nonvaccinated sows developed severe lesions, including swelling and necrosis of enterocytes and severe villus atrophy. Pigs inoculated when they were 5 days old and suckling sows vaccinated with attenuated vaccines developed less-severe villus atrophy, and those suckling sows immunized by exposure to nonattenuated TGE virus developed moderate or no villus atrophy. Pigs inoculated when they were 21 days old and suckling sows vaccinated with attenuated vaccines had severe villus atrophy, whereas those suckling sows immunized by exposure to nonattenuated virus had more-moderate villus lesions. Villus atrophy was inhibited to various degrees in pigs suckling immunized sows, depending in part on the antibody titer in the colostrum and milk.     

Development of a genetically modified nontoxigenic Pasteurella multocida toxin as a candidate for use in vaccines against progressive atrophic rhinitis in pigs

OBJECTIVE: To construct a genetically modified nontoxigenic Pasteurella multocida toxin (PMT) and examine its immunoprotective activity against challenge exposure with wild-type PMT in pigs. ANIMALS: 5 healthy pigs. PROCEDURE: A nontoxigenic PMT was created by replacing the serine at position 1164 with alanine (S1164A) and the cysteine at position 1165 with serine (C1165S). Toxic activity was determined by use of the guinea pig skin test and mouse lethality test. Three pigs were vaccinated twice with the modified PMT, and the remaining 2 pigs served as nonvaccinated control animals. Vaccinated and control pigs were challenge exposed with wild-type PMT. Pigs were euthanatized and necropsied on day 14 after challenge exposure. Turbinate atrophy was examined macroscopically and assigned a score. Serum anti-PMT antibodies were determined by use of an ELISA. RESULTS: The genetically modified PMT was characterized by a total lack of toxic activity. Pigs vaccinated with the modified PMT became seropositive; in contrast, control pigs remained seronegative. Necropsy revealed that the 2 control pigs had moderate and severe turbinate atrophy, respectively, whereas the 3 vaccinated pigs did not have any lesions in the turbinates or abnormalities in other organs. CONCLUSIONS AND CLINICAL RELEVANCE: Modification by use of S1164A and C1165S leads to a complete loss of toxic effects of PMT without impairment of the ability to induce protective immunity in pigs. Analysis of these results suggests that genetically modified PMT may represent a good candidate for use in developing a vaccine against progressive atrophic rhinitis in pigs.     

Effects of purified Pasteurella multocida dermonecrotoxin on the nasal ventral turbinates of fattening pigs: histological observations.

Fattening specific pathogen-free derived pigs were injected intramuscularly with dermonecrotoxin of Pasteurella multocida, capsular type D. Ten days later, the nasal ventral turbinates and liver were examined histologically. A moderate turbinate atrophy was observed due to an increased number of osteoclasts and the absence of intramembranous bone apposition. Liver lesions were limited to some hepatocyte necrosis, sinusoid neutrophil infiltration and Kupffer cell hypertrophy. This study demonstrated that adult pigs are sensitive to P. multocida dermonecrotoxin.     

Long-acting oxytetracycline for control of induced Pasteurella multocida rhinitis in swine

A long-acting oxytetracycline formulation was evaluated for control of rhinitis induced experimentally in pigs with a capsular type A, toxin-negative, low-passage strain of Pasteurella multocida. The pigs were 6 to 7 weeks old and were naturally infected with Haemophilus parasuis. The H parasuis infection was thought to predispose to establishment of P multocida in the nasal cavity. A long-acting oxytetracycline formulation was given IM at the rate of 20 mg/kg, 4 times at 5-day intervals. Medication reduced (P less than 0.05) the severity of turbinate atrophy and the proportion of pigs with P multocida and H parasuis in their nasal cavities. Numbers of colonies of P multocida and H parasuis isolated were also less in medicated pigs.     

Efficacy of Bordetella bronchiseptica bacterin in controlling enzootic atrophic rhinitis in swine.

The efficacy of a Bordetella bronchiseptica bacterin was evaluated in 2 commercial swine herds affected with mild and severe enzootic atrophic rhinitis (AR). In the 1st herd study, (mild AR), the degree of clinical AR, nasal turbinate evaluation, blood serum titer to B bronchiseptica antigen, and adjusted days from birth to 100 kg were determined for individual pigs. Bacterin inoculation reduced the incidence and severity of gross turbinate atrophy 57% and reduced clinical AR over 93%. Inoculated swine had an average blood serum-agglutinating titer greater than 1:2,793 and noninoculated (control) swine had an average titer of 1:112. Increased serum titer significantly (P less than 0.05) correlated with decreased degree of nasal turbinate atrophy. Inoculated and control pigs reached 100 kg in an average of 171 and 178 days after birth, respectively. In the 2nd study (severe enzootic AR), inoculated and control pigs were individually evaluated for clinical AR and total average daily weight gain. Inoculation reduced clinical AR over 90%. The total average daily gain for the inoculated and control pits was 435.84 g and 340.50 g, respectively. Inoculated pigs and control pigs reached 100-kg market weight in 184 and 238 days, respectively.     

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.     

Epidemiology and control of Menangle virus in pigs

OBJECTIVE: To describe the epidemiology and eradication of Menangle virus infection in pigs. DESIGN: Field observations and interventions, structured and unstructured serological surveys, prospective and cross-sectional serological studies and laboratory investigations. PROCEDURE: Serum samples were collected from pigs at a 2600-sow intensive piggery in New South Wales that experienced an outbreak of reproductive disease in 1997. Serum samples were also collected from piggeries that received pigs from or supplied pigs to the affected piggery and from other piggeries in Australia. Serum and tissue samples were collected from pigs at piggeries experiencing reproductive disease in New South Wales. Sera and faeces were collected from grey-headed flying foxes (Pteropus poliocephalus) in the region of the affected piggery. Serum samples were tested for neutralising antibodies against Menangle virus. Virus isolation was attempted from faeces. RESULTS: Following the outbreak of reproductive disease, sera from 96% of adult pigs at the affected piggery, including sows that produced affected litters, contained neutralising antibodies against Menangle virus. Neutralising antibodies were also detected in sera from 88% of finisher pigs at two piggeries receiving weaned pigs from the affected piggery. No evidence of Menangle virus infection was found in other piggeries in Australia. In cross-sectional studies at the affected piggery, colostral antibodies were undetectable in most pigs by 14 to 15 weeks of age. By slaughter age or entry to the breeding herd, 95% of pigs developed high antibody titres (> or = 128) against Menangle virus in the virus neutralisation test. Menangle virus was eradicated from the affected piggery following a program of serological testing and segregation. Neutralising antibodies against Menangle virus were also detected in P poliocephalus from two colonies in the vicinity of the affected piggery. Two piggery workers were infected with Menangle virus. There was no evidence of infection in cattle, sheep, birds, rodents, feral cats and a dog at the affected piggery. CONCLUSIONS: Serological evidence of infection with Menangle virus was detected in pigs at a piggery that had experienced reproductive disease, in pigs at two associated piggeries and in fruit bats in the region of the piggery. Two humans were infected. The mode of transmission between pigs is unknown, but spread by faecal or urinary excretion is postulated. This virus can be eradicated by the segregation of pigs into discrete age groups.     

The pathogenesis of persistent turbinate atrophy induced by toxigenic Pasteurella multocida in pigs

Six one-week-old piglets were pretreated with a 1% acetic acid solution for two days in one or both nostrils. Three piglets were not treated with acetic acid. Three days after treatment all nine piglets were inoculated in both nostrils with a toxigenic type D strain of Pasteurella multocida. Three piglets were killed seven days after inoculation; one died spontaneously 13 days after inoculation and the remaining pigs were killed at approximately 90 kg body weight, i.e., five to six months of age. All acetic acid-treated animals developed severe atrophy of the turbinates in the treated nostrils. Untreated nostrils were normal. The present results showed that toxigenic P. multocida can induce turbinate atrophy that persisted until 90 kg body weight when the lesions were similar to spontaneous atrophic rhinitis in pigs. The turbinate atrophy was not accompanied by inflammatory reaction, atrophy of other bone structures, or lesions in other organs. The experiment showed furthermore that toxigenic P. multocida may be present in the tonsils of control animals without causing turbinate atrophy. A pathogenesis for atrophic rhinitis in pigs is proposed.