Mycoplasma Gallisepticum Bacterin Research Articles

Chitosan-adjuvanted Mycoplasma gallisepticum bacterin via intraocular administration enhances Mycoplasma gallisepticum protection in commercial layers.

Mycoplasma gallisepticum (MG) causes respiratory signs and economic losses in the poultry industry. MG vaccination is one of the effective prevention and control measures that have been used around the world. Our previous study demonstrated that chitosan-adjuvanted MG bacterin could effectively reduce pathological lesions induced by MG and that chitosan could be used as an adjuvant in MG bacterin. The present study determining the efficacy of MG bacterins against the Thai MG strain was based on vaccine programs. Seven groups (25 layers/group) were received MG bacterins containing 0.5% chitosan or a commercial bacterin via intramuscular (IM) or intraocular (IO) route at 6 and 10 wk of age. Sham-negative and sham-positive controls were groups 1 and 2, respectively. Group 3: IM route of chitosan bacterin followed by IM route of chitosan bacterin; group 4: commercial bacterin via IM route followed by chitosan bacterin via IO route; group 5: commercial bacterin via IM route followed by commercial bacterin via IM route; group 6: chitosan bacterin via IM followed by chitosan bacterin via IO route; and group 7: chitosan bacterin via IO route followed by chitosan bacterin via IO route were determined. At 16 wk of age, all groups, excluding group 1, were challenged intratracheally with 0.1mL containing Thai MG strain 107 colony-forming unit. At 17, 18, and 20 wk of age, 5 birds in each group were bled for serological testing and swabbed at the choanal cleft for the quantitative real-time PCR assay, the euthanized and necropsied. The results showed that birds vaccinated with a commercial intramuscular bacterin followed by an intraocularly chitosan adjuvant bacterin showed the best protection against the MG challenge. The study indicated that chitosan could be the effective mucosal adjuvant and increased the effectiveness of MG bacterin.

The Efficacy of Chitosan-Adjuvanted, Mycoplasma gallisepticum Bacterin in Chickens.

Mycoplasma gallisepticum (MG) is one of the major pathogens that cause respiratory signs in the poultry industry. To control MG infection, vaccination is the useful procedure. In this study, MG vaccine was developed by using the local Thai MG isolate (AHRL 20/52). Chitosan, a polysaccharide adjuvant derived from crustaceans, has been successfully used in various vaccines. The objectives of this study were to prepare MG bacterins by using chitosan, serving as an adjuvant, to determine protection against the field Thai MG isolate and to evaluate tissue reaction at the injection site. Six groups of 6-wk-old layers (20 birds/group) were intramuscularly vaccinated with bacterin containing various concentrations of chitosan (0.25, 0.5, and 1%), a commercially available MG bacterin, respectively. Sham-negative and sham-positive controls were included in the experiment. Six weeks postvaccination, all groups excluding the negative control were intratracheally challenged with 100 μl of 108 colony-forming units of Thai MG isolate (AHRL 58/46). At 1, 2, 3, and 4 wk postchallenge, five birds from each group were euthanatized and necropsied to determine the gross and histopathologic lesions. For a tissue reaction study, three groups of 24 birds each including sham negative control, 0.5% chitosan bacterin and commercial vaccine were given as previously described. At 1, 2, and 3 wk postvaccination, 8 birds from each group were randomly selected to euthanatize, necropsy, and determine the gross lesions, and 3 out of 8 birds were randomly selected to determine the histopathologic lesions. The results demonstrated that prepared bacterins induced lower numbers of positive antibody birds compared to the commercial vaccine, but groups receiving bacterin containing 0.5 and 1% chitosan exhibited significantly lower tracheal lesions than the positive control and commercial vaccine groups (P < 0.05). Chitosan formulation caused less tissue reaction than the commercial vaccine. These results demonstrated that the prepared MG bacterins could effectively reduce MG-induced pathologic lesions and that chitosan could be used as adjuvant in MG bacterins.

The Efficacy of Three Commercial Mycoplasma gallisepticum Vaccines in Laying Hens

The efficacy of three commercial Mycoplasma gallisepticum (MG) immunizing agents-a bacterin, a recombinant fowlpox-MG vaccine, and a live F-strain vaccine-was compared in specific-pathogen-free hens in egg production. Three groups of 25 chickens were vaccinated with one of the vaccines at 10 wk of age and 25 birds were not vaccinated. At 25 wk of age (and approximately 50% egg production), 20 birds from each of the three vaccinated groups and 15 nonvaccinated controls were challenged with virulent R-strain via aerosol; the birds were necropsied and evaluated at 10 days post-challenge. The MG bacterin and live F-strain vaccinations were both protective and resulted in significant differences in air sac lesions, tracheal lesions, and ovarian regression compared to the nonvaccinated controls and the recombinant fowlpox-MG vaccine (P < or = 0.05). The evaluation of ovarian regression is a useful method of testing the efficacy of MG vaccines in laying hens.

Facial Cellulitis Induced in Chickens by Mycoplasma gallisepticum Bacterin and Its Treatment

Ten-to-14-day-old replacement chickens were vaccinated subcutaneously in the neck with a Mycoplasma gallisepticum bacterin. A few days later, 40% of the flock developed cellulitis of the head. Birds were submitted for diagnostic investigation between 4 and 6 wk of age. Histology revealed lesions in the subcutis consistent with oil-emulsified vaccine/bacterin reaction. No significant bacteria were isolated from the lesions. Birds were treated with 1 mg of methyl prednisol acetate intramuscularly. Improvement was noted as early as 12 hr posttreatment. One week after treatment only 1%-2% of the flock still had facial cellulitis.

Facial Cellulitis Induced In Chickens By Mycoplasma gallisepticum Bacterin and Its Treatment

Facial Cellulitis Induced In Chickens By Mycoplasma gallisepticum Bacterin and Its Treatment

Local Reaction and Serological Response in Commercial Layer Chickens Injected Intramuscularly in the Leg with Oil-Adjuvanted Mycoplasma gallisepticum Bacterin

The incidence of local vaccine reaction was investigated in three flocks of commercial layer chickens after they were vaccinated intramuscularly in the leg with oil-adjuvanted Mycoplasma gallisepticum (MG) bacterin by commercial crews. Local vaccine reaction typically involved swelling due to a granulomatous cellulitis in the connective tissue above the tibiotarsal joint of the vaccinated leg. Histopathology revealed that the inflammatory reaction was confined primarily to subcutis and muscle fascia and rarely extended into muscle fibers, tendons, or tendon sheaths. Movement of the vaccinated flocks from growing to laying houses was associated with a significant increase in the incidence and severity of leg swelling. Antibodies against MG as measured by the hemagglutination-inhibition test were significantly higher in chickens with severe leg swelling than in chickens without leg swelling.

A Comparative Study of Mycoplasma gallisepticum Vaccines in Young Chickens

Ten-day-old leghorn chickens were vaccinated with the F, ts-11, or 6/85 strain of Mycoplasma gallisepticum (MG) via the intraocular route or subcutaneously with MG bacterin and challenged by aerosol with the R strain of MG at 30, 60, or 90 days post-vaccination. Respiratory reaction post-vaccination, serological response, persistence of the vaccine strain, and protection against aerosol challenge were compared. In general, the ts-11 and 6/85 strains induced a milder post-vaccination reaction than F-strain, produced a weaker serological response, and did not persist as long in the upper respiratory tract. The F-strain-vaccinated chickens had the fewest and mildest air-sac lesions post-challenge, the 6/85 and ts-11 groups had somewhat less protection, and bacterin-vaccinated chickens had no detectable protection against airsacculitis. The F-strain-vaccinated chickens also had the fewest MG organisms in the trachea 10 days postchallenge.

Protection against airsacculitis with sequential systemic and local immunization of chickens using killed Mycoplasma gallisepticum bacterin with iota carrageenan adjuvant

The induction of protective immunity to Mycoplasma gallisepticum (MG) by bacterins containing 0.2% iota carrageenan (iCGN) as an adjuvant has been studied. Various combinations of intracoelomic (i.c.), intratracheal (i.t.), intranasal (i.n.), intravenous (i.v.), subcutaneous (s.c.) and oral immunization routes were evaluated. Vaccinated and non-vaccinated groups were compared with a group vaccinated s.c. with a commercial bacterin. Primary i.c. immunization with the bacterin was as effective as commercial bacterin and was more effective when followed by i.n. or i.t. immunization. Oral immunization was ineffective, in contrast to observations reported with mice. The i.c./i.n. and i.c./i.t. combinations were the most effective, produced the highest levels of anti-MG IgG and IgA in serum and tracheobronchial washes, and sometimes provided 100% protection against air sac lesions. Chickens vaccinated by the i.c./i.n. or i.c./i.t. routes had the fewest virulent organisms in their respiratory tract secretions. These results demonstrated that i.c. immunization followed by local immunization with the bacterin is most efficacious in protecting chickens against airsacculitis.

Comparison of Immunity Induced with a Mycoplasma gallisepticum Bacterin between High- and Low-Responder Lines of Chickens

Chickens of the high-responder line GSP and low-responder line BM-C, which had been known to have different antibody responses to Mycoplasma gallisepticum (MG) antigen, were immunized by intramuscular injection and by subsequent intratracheal instillation of MG bacterin. They were then challenged with the pathogenic strain SAS of MG. The preventive effects of local antibodies detectable in the trachea, saliva, and lacrima were compared between the two lines of chickens. The local antibody responses, as determined by an enzyme-linked immunosorbent assay, were higher in line GSP than in line BM-C before and after challenge. Following challenge, chickens of both lines were protected from colonization by MG and the development of respiratory lesions. The degree of protection in line GSP was higher than that of line BM-C. The results suggest that local antibodies may play an important role in the host defense mechanism to respiratory MG infection.

Effect of Mycoplasma gallisepticum Bacterin on Egg-Transmission and Egg Production

Groups of white leghorn hens were vaccinated twice with a Mycoplasma gallisepticum (MG) bacterin, once with bacterin, or left unvaccinated. Four weeks after vaccination, they were challenged with virulent R strain MG. Egg production was significantly higher in challenged vaccinated groups than in the challenged control group. Four challenged control hens went out of production, whereas only one twice-vaccinated hen did. MG was first isolated directly from eggs 5 days postchallenge (PC) in twice-vaccinated hens, 4 days PC in once-vaccinated hens, and 2 days PC in controls, and the hens continued to lay positive eggs till the end of the experiment 7 weeks PC. MG was found in 17.65%, 38.55%, and 45.90% of eggs cultured in twice-vaccinated, once-vaccinated, and control groups, respectively. Nine of 16 twice-vaccinated hens were found to be shedding MG through their eggs, whereas 15 of 17 once-vaccinated hens and 14 of 16 controls were shedding MG through their eggs.

Immunity Induced with an Aluminum Hydroxide-Adsorbed Mycoplasma gallisepticum Bacterin in Chickens

The protective effect of an inactivated Mycoplasma gallisepticum (MG) bacterin was evaluated in chickens subsequently challenged intratracheally (IT) with the homologous strain. Antibody responses in sera and tracheal washings (TWs) from these chickens were determined by an enzyme-linked immunosorbent assay. A group of chickens was vaccinated intramuscularly (IM) with two doses of the bacterin containing aluminum hydroxide gel (IM + IM). Another group was vaccinated IM with the same bacterin followed by IT with bacterin lacking the adjuvant (IM + IT). Chickens of both vaccinated groups had similar levels of antibody in TWs at the time of challenge. MG was eliminated from the trachea at higher rates and inflammatory lesions in the trachea were less severe in vaccinated chickens than in unvaccinated controls. The protective effect in chickens vaccinated IM + IT was greater than that in chickens vaccinated IM + IM. Perhaps vaccinal immunity is mediated by local rather than systemic antibody responses, or perhaps resistance provided by vaccination IM + IT is conferred partly by another immune mechanism such as cell-mediated immunity.

Efficacy of Commercial Mycoplasma gallisepticum Bacterin (MG-Bac [Registered Trademark]) in Preventing Air-Sac Lesions in Chickens

One-week-old chickens were vaccinated with commercial Mycoplasma gallisepticum bacterin subcutaneously and challenged with the S6 strain by the intra-air-sac route 3 weeks later. Significantly fewer vaccinated chickens had air-sac lesions than controls.

Observations on Commercial Layers Vaccinated with Mycoplasma gallisepticum (MG) Bacterin on a Multiple-Age Site Endemically Infected with MG

A commercially available inactivated Mycoplasma gallisepticum (MG) bacterin was administered to chickens on a multiple-age farm endemically infected with MG. A total of 3400 MG-free pullets were vaccinated with the MG bacterin at 19 weeks of age, and 4300 unvaccinated pullets served as controls. The vaccinated group became serologically positive by the rapid plate agglutination (RPA) test within 3 weeks, and the unvaccinated group became positive in 7 weeks. The hemagglutination-inhibition test responses were observed at approximately the same time as the RPA in both of the groups. Egg production and mortality through 50 weeks of age did not differ significantly between the two groups. MG was isolated from birds of the vaccinated and control groups near the termination of the study.

Bacterin to Control the Vertical Transmission of Mycoplasma gallisepticum in Chickens

A Mycoplasma gallisepticum bacterin was prepared and used in Mycoplasma gallisepticum (MG)-positive primary breeders to control vertical transmission of MG. Two generations were vaccinated, but the third generation was not vaccinated and was monitored serologically. Results showed no evidence of MG at 1 day, 6 weeks, 11 weeks, 16 weeks, or 31 weeks of age. This procedure may offer small breeder organizations and showbird fanciers a way to eliminate MG.

Evaluation of Protection against Colonization of the Chicken Trachea Following Administration of Mycoplasma gallisepticum Bacterin

Twelve-week-old commercial white leghorn pullets were given one or two doses of an inactivated oil-emulsion Mycoplasma gallisepticum (MG) vaccine or kept as unvaccinated controls. At 24 weeks of age, all groups were challenged intratracheally with one of six dilutions of a low-passage R strain of MG. Three days postchallenge, the tracheas from all chickens were cultured for MG to determine the number of challenge organisms required to initiate infection. The log10 ID50 of chickens vaccinated 0, one, or two times was 2.9, 3.4, and 3.7, respectively, and the minimum infectious dose (the lowest challenge dose to infect a single bird) was 15, 150, and 1500 colony-forming units, respectively. It was concluded that the vaccine provided measurable, though limited, protection against infection under these experimental conditions.

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.

Efficacy of Experimental Inactivated Mycoplasma gallisepticum Oil-Emulsion Bacterin in Egg-Layer Chickens

Six groups of white leghorn pullets were studied to determine the ability of beta-propiolactone-inactivated Mycoplasma gallisepticum (MG) oil-emulsion bacterins to counteract reductions in egg production caused by MG infection. The pullets were inoculated with 0.5 ml of MG bacterin subcutaneously in the neck at about 20 weeks of age and were challenged with MG near 28 weeks of age, when they were in peak egg production. Various challenge schemes with infectious bronchitis virus were used at the time of MG challenge to increase the reduction in egg production. MG bacterins afforded protection against moderate drops in egg production in at least three of the studies, where the unvaccinated challenged control hens exhibited reduced egg production.

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.

Evaluation of Inactivated Mycoplasma gallisepticum Oil-Emulsion Bacterins for Protection against Airsacculitis in Broilers

Broiler chicks were vaccinated subcutaneously in the neck at various ages with a single 0.5-ml dose of beta-propiolactone-inactivated Mycoplasma gallisepticum (MG) oil-emulsion bacterin. Four weeks later, vaccinated and control chicks were placed in cold environmental cabinets, infected with infectious bronchitis virus intratracheally, and 2 days later challenged by aerosol exposure to live MG broth culture. All chicks were killed 21 days later and scored postmortem for the rate and severity of airsacculitis produced in each group. Broiler chicks vaccinated at 1 day of age had only slight protection against the development of airsacculitis. Results were variable when chicks were vaccinated at 7 days of age, with little evidence of resistance to airsacculitis. However, when broiler chicks were vaccinated with MG bacterins at 11 to 15 days of age, they acquired significant protection against airsacculitis compared with controls. Viable MG organisms were readily isolated from most of the sampled tracheas and air-sac lesions cultured 21 days post-challenge, indicating a lack of protection against infection of the respiratory tract. MG-vaccinated chicks generally produced antibodies readily detectable by the rapid serum-plate test, tube-agglutination, and hemagglutination-inhibition (HI) tests. Some of the vaccinated chicks, but none of the unvaccinated control chicks, developed positive reactions to agar-gel-precipitin tests following challenge. Low HI titers at challenge were not necessarily indicative of lack of protection against the development of airsacculitis, since good protection was often observed in chickens with low to moderate HI titers.

Mycoplasma gallisepticum (MG): Laboratory and Field Studies Evaluating the Safety and Efficacy of an Inactivated MG Bacterin

A highly antigenic isolate of Mycoplasma gallisepticum (MG) was utilized in the production of an inactivated, oil-emulsified MG bacterin (MGB). Laboratory tests indicated that the bacterin was capable of protecting chickens from clinical signs of MG caused by intrasinus challenge with the R, S-6, PG-31, or 1150 strain of MG. Vaccinated turkeys also were protected from clinical signs of disease when challenged with MG. Use of the MGB in chickens under laboratory conditions resulted in a reduction in airsacculitis from 44% in nonvaccinates to 10% in vaccinates and further reduced the number of organisms present in the trachea post-challenge. Commercial chickens vaccinated subcutaneously midway or lower in the nape of the neck showed no untoward effects due to the bacterin. Those improperly vaccinated at the base of the skull developed a transient edema around the eye(s). This swelling did not appear to affect the performance of the chickens and had been reabsorbed by the next observation period. Subcutaneous inoculation should be at the mid or lower neck region. Field trials at a commercial egg operation comparing production efficiency showed that chickens vaccinated with the MGB had higher egg production, a greater percentage of eggs graded large and over, a smaller percentage of undergrades, and better feed conversion than chickens vaccinated with a live-culture, low-virulence Conn-F strain vaccine. The results of these studies indicate that the oil-emulsified MG bacterin is safe and highly efficacious.