Control of avian mycoplasmoses by vaccination

Pereira

Rev. Bras. Cienc. Avic.

et al. 2005

Avian mycoplasmas occur in a variety of bird species. The most important mycoplasmas for chickens and turkeys are Mycoplasma gallisepticum (MG), M. synoviae (MS), and M. meleagridis. Besides, M. iowe (MI) is an emerging pathogen in turkeys, but of little concern for chickens. Mycoplasmas are bacteria that lack cell wall and belong to the class Mollicutes. Although they have been considered extracellular agents, scientists admit nowadays that some of them are obligatory intracellular microorganisms, whereas all other mycoplasmas are considered facultative intracellular organisms. Their pathogenic mechanism for disease include adherence to host target cells, mediation of apoptosis, innocent bystander damage to host cell due to intimate membrane contact, molecular (antigen) mimicry that may lead to tolerance, and mitotic effect for B and/or T lymphocytes, which could lead to suppressed T-cell function and/or production of cytotoxic T cell, besides mycoplasma by-products, such as hydrogen peroxide and superoxide radicals. Moreover, mycoplasma ability to stimulate macrophages, monocytes, T-helper cells and NK cells, results in the production of substances, such as tumor necrosing factor (TNF-α), interleukin (IL-1, 2, 6) and interferon (α, β, γ). The major clinical signs seen in avian mycoplasmosis are coughing, sneezing, snicks, respiratory rales, ocular and nasal discharge, decreased feed intake and egg production, increased mortality, poor hatchability, and, primarily in turkeys, swelling of the infraorbital sinus(es). Nevertheless, chronic and unapparent infections are most common and more threatening. Mycoplasmas are transmitted horizontally, from bird to bird, and vertically, from dam to offspring through the eggs. Losses attributed to mycoplasmosis, mainly MG and MS infections, result from decreased egg production and egg quality, poor hatchability (high rate of embryonic mortality and culling of day-old birds), poor feed efficiency, increase in mortality and carcass condemnations, besides medication costs. Mycoplasmas are diagnosed by serologic tests, culture and PCR and are sensitive to antimicrobials whose action sites are other than the bacterial cell wall, such as tetracyclines, macrolides, quinolones and tiamulin. However, mycoplasma control is more efficiently achieved by acquisition of birds free of MG, MS, MM and/or MI, vaccination of layers, and monitoring of breeder flocks, followed by elimination of the infected flocks that are detected.

Section: Treatment and Immunoprofilaxismentioning

confidence: 99%

Section: Treatment and Immunoprofilaxismentioning

confidence: 99%

Avian mycoplasmosis update

Pereira

Rev. Bras. Cienc. Avic.

et al. 2005

“…Attenuated vaccines stimulate immune responses by cellular and humoral basis and act as an instrument of competitive exclusion in relation to field MG strains (Cummings & Kleven 1986, Whithear 1996. There are four live MG vaccine types available, i.e., F-Conn strain (MG-F), ts-11, 6/85 and MG-70 which can reduce drop in egg production, although they are not able to prevent transovarial transmission (Carpenter et al 1981, Glisson & Kleven 1984.…”

Section: Introductionmentioning

confidence: 99%

Transmission, serologic and tissue responses in chickens vaccinated with Mycoplasma gallisepticum F strain (MG-F)

Machado

Santos

et al. 2016

Pesq. Vet. Bras.

MG-F protects chickens from MG Mycoplasmosis and monitoring is done by serology (SAR and ELISA) and PCR. Histopathology is used to evaluate bird response to MG. This study evaluated MG-F profile vaccination in SPF chicken. This trial used 100 chickens, being 40 unvaccinated (G1), 40 eye-drop vaccinated at 8 weeks of age with MG-F ( Ceva Animal Health , São Paulo , SP , Brazil ) (G2) and 20 immunized by contact (G3) . Samples were obtained on the 8th, 12th, 15th, 18th, 20th and 24th week for SAR, ELISA and PCR. Fragments of trachea and air sac, for microscopy, were got after necropsies on the 15th and 24th week. Up to 12 weeks there was no significant difference among groups by SAR. SAR reactions appeared from the 15th week with these averages: G1 (1.7, 1.76 , 0.1, 0.15) , G2 (7.81, 7.65, 8.25, 6.29) and G3 (8.1, 8.5, 9.5, 6.16), while by ELISA it occurred after the 18th week with optical densities averages: G1 (0.19, 0.14, 0.16) , G2 (0.47, 0.45, 0.41) and G3 (0.55, 0.51, 0.51) . Positivity in G3 by PCR occurred seven weeks after exposure. At the 15th week the air sac score means were 0.20, 0.55, and 0.32 and 24th week were 0.15, 0.80 and 0.66 (p>0.05). For trachea, G2 (0.48) yielded higher score average than G1 (0.10) and G3 (0.00) on the 15th week. Changes in G3 were seen only at 24th week, being this average (1.00) significantly different (p<0,05) from G1 (0.08) and G2 (0.46). SAR and PCR detected MG-F in G3 earlier than ELISA. Higher tracheal changes for G2 and G3 as compared to G1 could be ascribed to MG-F vaccine infection.

“…This suggests that it could be safer than the MG-F strain for vaccinated flocks. The ability to replace wild or vaccine MG strain has originated controversy among researchers (11,23).…”

Section: Introductionmentioning

confidence: 99%

“…These techniques have made it feasible to determine if MG-F strain long-term used as a vaccine in multiple-age commercial layers has resulted in displacement of the original field strain with the F vaccine strain. Random amplified polymorphic DNA analysis was used to discriminate between F and TS-11 strain (3), but one of the disadvantages of current available vaccines is that there is no convenient serological technique to accurately distinguish between vaccinated or naturally infected flocks (23). A MG marker to distinguish vaccine from wild type-strains would be useful as diagnostic tool.…”

Section: Introductionmentioning

confidence: 99%

Phenotypic and antigenic variation of Mycoplasma Gallisepticum vaccine strains

Ferraz¹,

Danelli²

2003

Braz. J. Microbiol.

Phenotypic and antigenic variations among Mycoplasma gallisepticum vaccine F and Ts-11 strains were investigated by SDS-PAGE and serological methods (hemagglutination-inhibition and immunoblot assays). The SDS-PAGE system followed by densitometer analysis showed weak phenotypic variability between the strains, being the major difference close to the 75 kDa level where a prominent peptide band was detected only in the F vaccine strain. Polyclonal antibodies to the M. gallisepticum antigens produced in chickens were used in serological tests for this antigenic variability study. There were strong cross-reactions between the strains and homologous/ heterologous antibodies. The most evident characteristic was the specific response of the vaccine-type F polyclonal antiserum to the 75 kDa peptide band of the homologous strain.