A serotypic survey of Pasteurella multocida isolated from poultry   总被引：6，自引：0，他引：6  

C L Hofacre  J R Glisson 《Avian diseases》1986,30(3):632-633

One hundred forty-eight Pasteurella multocida isolates from four southeastern states and California were serotyped by a gel diffusion precipitin test. The isolates were predominantly from turkeys and chickens. Sixty-eight percent of the isolates had antigenic characteristics of serotypes 3 and 4 (3 X 4). In turkeys, 76% of the isolates were 3 X 4, and serotype 3 was second (17%) in frequency. In chickens, 54% of the isolates were 3 X 4 and 19% were serotype 1.  相似文献   

Severe disease following experimental exposure of calves to noncytopathic bovine viral diarrhoea virus isolate New York-1   总被引：1，自引：0，他引：1  

DJ MARSHALL  RA MOXLEY  CL KELLING 《Australian veterinary journal》1998,76(6):428-430

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Antigenic stability of fimbriae of Bacteroides nodosus     

LJ MOORE  AT CROWE  M NORMAN  CL KRISTO  JR EGERTON 《Australian veterinary journal》1990,67(6):219-223

Successful vaccination of sheep against footrot and attempts to eradicate the disease depend on there being a limit to the antigenic diversity of the causative bacterium, Bacteroides nodosus. Fimbrial antigenic variation was therefore investigated in vivo, both under conditions of chronic infection and under the pressure of a vaccine-induced immune response, to ascertain whether this represented an obstacle to such goals. Material was available from 5 experiments and although B. nodosus appeared to have undergone changes in its fimbrial antigens in one of these, the possibility that superinfection was responsible for the variation detected could not be ruled out because all sheep in this case were maintained at pasture. Overall, the results provided no evidence of fimbrial antigenic shift in B. nodosus in vivo and in conclusion, the survival of the organism in the sheep's foot, both in long-term natural infection and following vaccination, must therefore be related to factors other than the ability to undergo antigenic variation in order to evade the host's immune response.  相似文献   

Evaluation of Pasteurella multocida mutants of low virulence. I. Development and pathogenicity   总被引：1，自引：0，他引：1  

C L Hofacre  J R Glisson  S H Kleven  J Brown  G N Rowland 《Avian diseases》1989,33(2):270-274

Mutagenesis of the Clemson University (CU) vaccine strain of Pasteurella multocida with N-methyl-N-nitro-N-nitrosoguanidine resulted in temperature-sensitive mutants that grew at 37 C but not at 42 C. Seven such mutants were evaluated for immunogenicity in turkeys. From these seven, only two, PM#1 and PM#3, provided turkeys with a level of protection against challenge with a virulent serotype 3 P. multocida strain (P-1059) comparable to the protection provided by the CU strain. Intravenous (IV) inoculation of PM#1, PM#3, or CU was used to assess differences in virulence. PM#1 and PM#3 resulted in lower rates of mortality and lameness than the CU strain. Histopathological evaluation of spleens 24, 48, and 72 hours after IV inoculation demonstrated that the CU strain induced significantly more fibrinoid necrosis of the spleen than either PM#1 or PM#3.  相似文献   

Newcastle disease vaccination of broilers with high- and low-titered commercial vaccines     

C L Hofacre  P Villegas  R K Page 《Avian diseases》1986,30(3):623-627

The virus titers of seven commercial B1 strain Newcastle disease vaccines were evaluated. A 2 log difference in virus content was found between the vaccine with the highest titer (10(8.8) EID 50/ml) and the one with the lowest titer (10(6.8) EID 50/ml). Broiler chickens were vaccinated with the high- and low-titered vaccines to compare hemagglutination-inhibition (HI) antibody and challenge responses. The effect of vaccination at different ages on the HI titers was also examined. There were no significant differences between vaccine groups in HI antibody response or resistance to challenge. However, the high-titered vaccine may provide a margin of safety with the currently used methods of mass vaccination.  相似文献   

Coccidia-induced mucogenesis promotes the onset of necrotic enteritis by supporting Clostridium perfringens growth     

Collier CT  Hofacre CL  Payne AM  Anderson DB  Kaiser P  Mackie RI  Gaskins HR 《Veterinary immunology and immunopathology》2008,122(1-2):104-115

This study tested the hypothesis that a host mucogenic response to an intestinal coccidial infection promotes the onset of necrotic enteritis (NE). A chick NE model was used in which birds were inoculated with Eimeria acervulina and E. maxima and subsequently with Clostridium perfringens (EAM/CP). A second group of EAM/CP-infected birds was treated with the ionophore narasin (NAR/EAM/CP). These groups were compared to birds that were either non-infected (NIF), or infected only with E. acervulina and E. maxima (EAM), or C. perfringens (CP). The impact of intestinal coccidial infection and anti-coccidial treatment on host immune responses and microbial community structure were evaluated with histochemical-, cultivation- and molecular-based techniques. Barrier function was compromised in EAM/CP-infected birds as indicated by elevated CFUs for anaerobic bacteria and C. perfringens in the spleen when compared to NIF controls at day 20, with a subsequent increase in intestinal NE lesions and mortality at day 22. These results correlate positively with a host inflammatory response as evidenced by increased ileal interleukin (IL)-4, IL-10 and IFN-gamma RNA expression. Concurrent increases in chicken intestinal mucin RNA expression, and goblet cell number and theca size indicate that EAM/CP induced an intestinal mucogenic response. Correspondingly, the growth of mucolytic bacteria and C. perfringens as well as alpha toxin production was greatest in EAM/CP-infected birds. The ionophore narasin, which directly eliminates coccidia, reduced goblet cell theca size, IL-10 and IFN-gamma expression, the growth of mucolytic bacteria including C. perfringens, coccidial and NE lesions and mortality in birds that were co-infected with coccidia and C. perfringens. Collectively the data support the hypothesis that coccidial infection induces a host mucogenic response providing a growth advantage to C. perfringens, the causative agent of NE.  相似文献