Fowl cholera vaccination of growing turkeys with CU strain via routes other than oral

Turkeys developed a high level of protective immunity and serum anti-Pasteurella multocida antibody when vaccinated with the Clemson University (CU) strain of P. multocida via the following routes: wing-web puncture with the recommended dosage or 1:10 dilution of this dosage, subcutaneous, crop injection, cloacal perfusion of the bursa of Fabricius, and intratracheal. The development of immunity after vaccination via the wing-web puncture and subcutaneous routes was dose-dependent: the lower dosages induced less serum antibody and protective immunity. Immunity was greatest 3 weeks after vaccination via wing-web puncture, although immunity was evident as early as 4 days after vaccination. A high level of antibody and protective immunity with no adverse reactions was induced by vaccinating twice, either by the drinking water followed by a similar dosage parenterally or by a parenteral route followed by the drinking water; these regimens were similar to one vaccination in the drinking water. Vaccination via wing-web puncture and possibly subcutaneous injection and bursal perfusion could be used for flocks with a history of a high mortality after vaccination with the CU vaccine in the drinking water and suspected of being immunosuppressed.     

Effects of bursectomy, irradiation, and cyclophosphamide on turkeys vaccinated with CU cholera strain

Turkeys surgically bursectomized, irradiated, and/or injected with cyclophosphamide at 1 day were vaccinated with the live Clemson University (CU) strain of Pasteurella multocida. Bursectomized turkeys vaccinated via drinking water or wing-web puncture at 7 weeks and challenged at 11 weeks had a significantly (P less than 0.05) lower survival rate after challenge than unbursectomized controls. Bursectomized and unbursectomized turkeys vaccinated via drinking water at 7 weeks, revaccinated via the auditory tube at 11 weeks, and challenged at 15 weeks had similar survival rates. The vaccinated bursectomized turkeys had significantly (P less than 0.05) lower levels of serum anti-P. multocida antibody than vaccinated unbursectomized controls. Radiation had no immunosuppressive effect. The immunosuppressive effect of cyclophosphamide was dosage-dependent. Bursectomy and injection of cyclophosphamide in the same turkey were complementary. It was concluded that in young turkeys, the development of immunity to the avirulent CU vaccine is highly dependent upon the bursa of Fabricius, but that as they grow older the bursa is of less importance, particularly if they were vaccinated via a parenteral route, such as in the air spaces of the head.     

Onset and duration of immunity and minimum dosage with CU cholera vaccine in turkeys via drinking water

Growing turkeys were partly protected against fowl cholera 4 days after vaccination with the live Clemson University (CU) strain of Pasteurella multocida administered in drinking water, and they were highly protected from 1 to 4 weeks after vaccination. The commercially available lyophilized vaccine and the freshly cultured vaccine of the CU strain did not differ in the level of immunity induced. Immunity was relatively high in turkeys vaccinated with 1:2 and 1:4 dilutions of the recommended dosage (4 X 10(8) P. multocida) but was significantly (P less than 0.05) lower in turkeys vaccinated with a 1:8 dilution of the recommended dosage. Immunity continued for 13 weeks after the last vaccination in turkeys vaccinated twice 3 weeks apart, but it persisted for only 8 weeks in those vaccinated only once.     

Comparison of vaccination protocols of broiler breeder hens for Pasteurella multocida utilizing enzyme-linked immunosorbent assay and virulent challenge

A commercial enzyme-linked immunosorbent assay (ELISA) to detect serological response to vaccination and virulent challenge with type 1 (X-73) Pasteurella multocida was used to determine the best vaccination protocol for broiler breeders against fowl cholera. Birds vaccinated twice, at 10 and 19 weeks of age, with the avirulent Clemson University (CU) strain both times, with a commercial bacterin first and the CU strain second, or with the CU strain first and bacterin second had the highest survival rates (98-100%) following challenge at 25 weeks. The two groups that received the CU strain and bacterin also produced the highest mean ELISA antibody titers (greater than 10,000). Birds vaccinated once, at 10 weeks, with the CU strain had the same survival rate as birds vaccinated twice with bacterin (90 and 91%). Under the conditions of this experiment, an ELISA titer greater than or equal to 1000 resulted in at least a 92% survival rate after virulent challenge (23% survival in nonvaccinates).     

Comparison of live avirulent M-9, Minnesota, and CU fowl cholera vaccines

The M-9 and Minnesota (MN) avirulent Pasteurella multocida vaccines were evaluated and compared with the Clemson University (CU) vaccine, which had been shown to be highly effective in preventing fowl cholera in turkeys. Neither the M-9 nor the MN vaccine given in the drinking water was as effective as the CU vaccine in protecting turkeys against challenge with virulent P. multocida. When grown in brain-heart infusion (BHI) agar as recommended, the M-9 was not as efficacious as when it was grown in BHI broth. The M-9 was as effective as the CU vaccine only when grown in BHI broth and given at 10 times the standard dosage. Injection of the M-9 vaccine into the air spaces of the head at a site near the caudal rim of the ear after one vaccination in the drinking water was not as effective for hyperimmunizing potential breeders as was the CU vaccine injected at the same site. A microtiter agglutination test demonstrated a significant (P less than 0.05) correlation between the level of anti-P. multocida antibody found 1 week after vaccination and survival after challenge with virulent P. multocida.     

Immunization of turkey breeder hens against fowl cholera by combined oral and wing-web administration of attenuated (CU) pasteurella multocida

Turkey breeder candidates were exposed to attenuated Pasteurella multocida (Clemson University strain) via both mouth (one or three times) and wing-web stick (one or two times). Significant protection lasting to 25-30 weeks post-vaccination was conferred under such immunization programs. The best protection with the fewest adverse effects of vaccination was established when orally vaccinated turkeys were subsequently vaccinated via wing-web at 20 and 25 weeks of age. High doses of attenuated P. multocida via wing-web produced lameness (synovitis and osteomyelitis) and severe wing lesions in growing turkeys.     

Attenutated live fowl cholera vaccine. III. Laboratory and field vaccination trials in turkeys and chickens

Administered via the drinking water, M-3-G, an attenuated strain of Pasteurella multocida of serotype 1, was found to immunize turkeys and chickens against fowl cholera. Immunity was tested by challenging birds intramuscularly, by palatine cleft swab, or orally after 3 vaccinations. No reactions to vaccination were noted in 390 turkeys in 12 laboratory trials, nor in 20,245 vaccinated in field trials. Chickens showed no vaccination reactions, and immunity was elicited by challenge in a laboratory trial and in face of natural outbreaks in the field, where 11,600 chickens were vaccinated. No vaccination reactions were noted, although most birds involved in the trials were carrying Mycoplasma spp. Immunity was found to last about 10 weeks after the last vaccination. The immunizing properties of M-3-G are compared with the CU strain.     

Fowl cholera immunity in broiler breeder chickens determined by the enzyme-linked immunosorbent assay

An enzyme-linked immunosorbent assay (ELISA) was developed to detect antibodies in broiler breeders vaccinated (wing web) with the CU fowl cholera vaccine. Birds were bled weekly from 9 to 26 weeks, every other week from 26 to 40 weeks, and every 4 weeks from 40 to 56 weeks of age. Overall mean ELISA antibody titers (9 to 56 weeks) reported as log10 values and survivability of the vaccinates after virulent challenge were as follows: unvaccinated--5.75, 48%; birds vaccinated once at 8 weeks--5.91, 78%; birds vaccinated twice at 8 and 14 weeks--6.11, 100%; birds vaccinated thrice at 8, 14, and 20 weeks--6.23, 100%; birds vaccinated twice at 8 and 20 weeks--6.12, 100%; and birds vaccinated twice at 8 and 20 weeks (plus fowl pox at 8 weeks)--6.08, 95%. Survivability in the vaccinates after virulent challenge with strain X-73 Pasteurella multocida was 100% in birds with ELISA antibody titers (log10) greater than 6.02. Under the conditions of this experiment, birds vaccinated two or three times between 8 and 20 weeks proved to be sufficiently immune at 56 weeks of age to withstand a virulent fowl cholera challenge. Birds not vaccinated or vaccinated only once at 8 weeks were not sufficiently immunized to withstand virulent challenge.     

Comparison of various antigens and their ability to detect protective antibodies against Pasteurella multocida using enzyme-linked immunosorbent assay

Various antigenic extracts of the CU strain of Pasteurella multocida were prepared to determine their suitability as plate antigens for use in the enzyme-linked immunosorbent assay (ELISA) for the detection of fowl cholera antibodies. Antisera from two separate broiler breeder flocks with known fowl-cholera-vaccination histories were collected just before the birds were challenged with virulent strain X-73 P. multocida. A potassium thiocyanate (KSCN)-extracted antigen, a capsular (CAP) antigen, a lipopolysaccharide-protein antigen, and heat-stable, salt-soluble antigen were all suitable as ELISA plate-coating antigens. Filtered and unfiltered sonicates of the CU strain of P. multocida were also suitable ELISA plate antigens. The results suggested that different plate antigens were detecting different populations of antibodies formed in response to fowl cholera vaccinations. When antibody titers were correlated with survival after challenge, the KSCN and the CAP plate antigens placed more nonsurvivors into low-antibody-titer ranges and more survivors (protected birds) into the high-antibody-titer ranges than the other plate antigens.     

Fowl cholera immunity induced by various vaccines in broiler minibreeder chickens determined by enzyme-linked immunosorbent assay

Broiler minibreeder hens were vaccinated for protection against fowl cholera at 12 and 21 weeks of age using several vaccination schemes, which included a live Pasteurella multocida (CU strain) vaccine, two commercial polyvalent fowl cholera oil-based bacterins, and two experimentally prepared polyvalent oil-based bacterins. Some treatment groups received only live or killed vaccines, whereas others received a live vaccine at 12 weeks followed by a killed product at 21 weeks. At 42 weeks of age, all birds that received the live CU vaccine twice or once followed by a bacterin survived challenge. Birds that received killed vaccines only were significantly less protected but still showed a respectable survival rate of 86%. All unvaccinated controls died within 72 hr after challenge. At 72 weeks of age, overall protection was lower than that at 42 weeks, regardless of vaccination treatment. Antibody titers were usually higher in birds that received bacterins than in those receiving live vaccines, yet overall protection was still greater in those birds that received the live cholera vaccine twice.     

Relationship between anti-Pasteurella multocida antibody titers after CU vaccination and survival after challenge

The relationship between serum anti-Pasteurella multocida antibodies and survival rates after challenge was determined in turkeys vaccinated one or more times with the live avirulent Clemson University (CU) vaccine and then challenged with a virulent isolate (9481) of P. multocida in the drinking water. A microtiter agglutination test for assaying anti-P. multocida serum antibodies demonstrated a highly significant (P less than 0.001) correlation between the serum antibody titer 1 week after the initial or single vaccination and the survival rate after challenge, and a significant (P less than 0.01) correlation between the antibody titer immediately before challenge and the survival rate after challenge. A highly significant (P less than 0.0001) correlation was also observed between the antibody titer before vaccination and the survival rate after challenge. This relationship was considered the result of an anamnestic response by the CU vaccine to a previous sensitization by antigens of other microbial organisms, probably in the intestine and similar antigenically to P. multocida. In contrast, a significant (P less than 0.05) but negative correlation was seen between the antibody titer 1 week after challenge and the survival rate. This relationship was thought to be the result of a marked stimulation of the antibody titer by the systemic infection of P. multocida that subsequently killed the turkeys.     

Evaluation of Pasteurella multocida mutants of low virulence. I. Development and pathogenicity

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.     

Mycoplasma gallisepticum vaccination: further studies on egg transmission and egg production

Leghorn hens vaccinated twice with an inactivated Mycoplasma gallisepticum (MG) bacterin before egg production and subsequently challenged with virulent MG were protected against transmission of MG through the egg. Unvaccinated control hens transmitted MG through the egg at a high rate. When unvaccinated hens were vaccinated with MG bacterin 2 weeks after challenge with MG, there was no significant decrease in egg transmission. Hens vaccinated twice before laying did not suffer as severe egg-production drops as unvaccinated hens did when challenged with virulent MG. In a natural MG outbreak in a leghorn breeder flock, 50 hens were separated from the remainder of the flock and vaccinated with MG bacterin approximately 3 weeks after initial exposure. The unvaccinated hens transmitted MG through the egg at a rate three times higher than the rate of transmission of the vaccinated hens.     

Pasteurella multocida infection in the domestic rabbit: immunization with a streptomycin-dependent mutant.

Fourteen Pasteurella multocida-free rabbits were inoculated intranasally with a streptomycin-dependent mutant of P. multocida serotype 12:A. Vaccinations with approximately 10(8) colony forming units were done on days 0, 14 and 28. Two weeks later the animals were separated into groups, which included 12 rabbits divided into two control groups of six unvaccinated Pasteurella-free animals. Seven vaccinated rabbits were challenged intranasally with the homologous virulent parent strain and the other seven vaccinates were challenged with a virulent strain of serotype 3:A. Rabbits were necropsied two weeks later. The vaccinated group challenged with the parent strain showed a more rapid nasal clearance of the organism than the vaccinated group challenged with the heterologous strain. However, the number of positive cultures of P. multocida recovered from tissues post-challenge were similar in vaccinated and control animals. In a significant number of animals, vaccination with serotype 12:A induced detectable antibody production to somatic antigens of both 12:A and heterologous strain 3:A.     

Mycoplasma gallisepticum vaccination: effects on egg transmission and egg production

The effects of Mycoplasma gallisepticum (MG) vaccination on egg transmission of MG and egg production were evaluated. Leghorn hens vaccinated with live MG (strain F), with strain F plus MG bacterin, with one dose of MG bacterin, or with two doses of MG bacterin all transmitted MG through the egg at a significantly lower level than unvaccinated controls. Hens vaccinated with two doses of MG bacterin had the longest lag before detectable transmission of MG through the egg. All vaccinated groups were protected against the egg-production drop seen in unvaccinated hens challenged with virulent MG.     

Effect of route of administration on the efficacy of a recombinant fowlpox virus against H5N2 avian influenza.

A recombinant fowlpox vaccine virus containing the H5 hemagglutinin gene of avian influenza virus was administered to susceptible chickens via wing-web puncture, eye drop, instillation into the nares, and drinking water. Even though there was a negligible hemagglutination-inhibition (HI) serologic response, all 10 chickens vaccinated by wing-web puncture remained without obvious signs of disease and survived challenge with a highly pathogenic strain of H5N2 avian influenza virus. All unvaccinated chickens and those vaccinated by nasal and drinking-water routes died following challenge. Eight of 10 chickens vaccinated with the recombinant by eyedrop died. All vaccinates were negative on the agar gel precipitin (AGP) test, and only one chicken had a positive HI titer before challenge. All chickens that survived challenge had high levels of HI antibody and were positive on the AGP test, indicating that they were infected by the challenge virus.     

种鸡接种网状内皮组织增生病病毒弱毒疫苗的安全性和免疫效果观察

在正常饲养条件下，在肉种鸡鸡群中试用网状内皮增生病病毒（reticuloendotheliosis virus，REV）的弱毒疫苗，观察其对体重增长、产蛋生产性能、对其他疫苗应答有无影响。同时连续定期测定种鸡血清REV抗体，并测试抗体阳性鸡的后代有无病毒垂直传播。结果表明，该疫苗接种18周龄种鸡后，对生长、产蛋率、受精率和孵化率等生产性能均无不良影响，对正常疫苗免疫的抗体应答也无影响。经免疫接种REV弱毒疫苗的种鸡，在开产后及产蛋高峰期，均不表现病毒的垂直传播。免疫种鸡后，其激发的抗体可持续280d以上，且雏鸡血清中母源抗体可持续至少7d。结果表明，该REV弱毒在开产前种鸡应用时有很高的安全性，并能为雏鸡提供足够的特异性母源抗体。     

Protection of laying hens against infectious bronchitis with inactivated emulsion vaccines

Commercially-reared laying chickens were challenged at 31 weeks of age with a virulent infectious bronchitis (IB) virus. They showed a sharp drop in egg production, despite having been vaccinated at four and eight weeks old with live attenuated IB vaccines to a recommended schedule. In contrast, similar birds that had been further immunised at point-of-lay with inactivated oil emulsion IB vaccine, or with a combined IB/Newcastle disease (ND) emulsion vaccine, showed no detectable fall in egg production after the same challenge. Unvaccinated susceptible specific pathogen-free birds challenged at the same time stopped laying almost completely. In the birds revaccinated with emulsion vaccine, measurement of haemagglutination inhibition antibody levels to IB showed their geometric mean titres to be raised from less than 5 log2 at the time of vaccination to over 10 log2 four weeks later. Their antibody levels did not rise further followining the IB challenge whereas in the birds that had not been revaccinated antibody rises to nearly 10 log2 were detected after the same challenge. For pullets vaccinated earlier with live IB vaccine, revaccination with inactivated IB or IB/ND oil emulsion vaccine at point-of-lay provides a safe and effective way of protecting their egg production against IB infection.     

Immunogenicity of Mycoplasma gallisepticum

The serological response and protective immunity elicited in the chicken by the pathogenic Ap3AS strain and the moderately pathogenic 80083 strain of Mycoplasma gallisepticum and variants of strain 80083 attenuated by repeated passage in mycoplasma broth were investigated. Strain 80083 elicited a substantial serum antibody response after administration either in drinking water or by conjunctival sac instillation to 7-week-old SPF chickens. No vaccinated chickens developed air sac lesions when challenged by intra-abdominal (IA) injection with the virulent Ap3AS strain. Chickens vaccinated with strain 80083M (50 broth passages) showed only a weak serological response but were substantially protected when challenged 4 weeks after vaccination. Chickens vaccinated with 80083H (100 broth passages) were serologically negative 4 weeks after vaccination and developed severe air sac lesions after challenge. Thirty-seven-week-old hens vaccinated 6 months previously with strain 80083 had high serum antibody levels and were completely protected against IA challenge with the homologous strain. However, 4/6 showed mild air sac lesions when challenged intra-abdominally with strain Ap3AS. Another group showed high M. gallisepticum serum antibody levels 6 months after vaccination with strain Ap3AS but 4/6 and 2/6 showed mild lesions after IA challenge with strains Ap3AS or 80083, respectively. Strains 80083 or 80083M were administered by conjunctival sac instillation to susceptible 11-week-old commercial pullets at the time of fowl pox vaccination. The concurrent use of both vaccines had no apparent adverse effect on the health of the chickens. Similar protection against IA challenge with strain Ap3AS was produced with the M. gallisepticum vaccines whether used alone or in combination with fowl pox.     

鸡新城疫、减蛋综合征、传染性支气管炎三联油佐剂灭活苗的研究Ⅰ、三联灭活苗对鸡免疫试验

用新城疫病毒克隆７９株，减蛋综合征病毒ＮＥ＿４株和传染性支气管炎病毒Ｍ＿（４１）株分别接种于鸡胚和鸭胚，并收取其鸡、鸭胚尿囊液毒，经甲醛灭活，按一定比例配比，以矿物油为佐剂制成三联油佐剂灭活苗。本苗接种于产蛋后备鸡，免疫后７天产生免疫应答，免疫后３０天保护率达９０％～１００％，免疫后六个月攻毒，ＮＤ和ＩＢ保护宰为１００％，ＥＤＳ＿（７６）为９５％。１９９２～１９９４上半年，本苗在江苏、安徽、山东等省的一些鸡场免疫十万余只鸡，均获得满意效果。