RETRACTED: Mycoplasma synoviae vaccine modifies virus shedding and immune responses of avian influenza (H9N2) infection in commercial layers

Abstract

Mycoplasma synoviae (MS) is an important pathogen of domestic poultry and is prevalent in commercial layers. Avian influenza (AI; H9N2) infections are emerging respiratory problems causing huge economic losses to the poultry industry, especially in the presence of other co-infecting pathogens. The possible role of MS vaccination and response to AI (H9N2) virus in commercial layers was evaluated during this study. Experimental commercial layers were divided into different groups which were identified as follows: non-vaccinated non-challenged (NVNC), non-vaccinated challenged (NVC), vaccinated non-challenged (VNC), and vaccinated challenged (VC). The titer of AI antibodies was measured pre- and post-challenge to confirm experimental infection. Infected layers showed clinical signs of differing severity, with the most prominent disease signs and mortality (25%) appearing in layers of the VC group. Moreover, the layers in VC group showed a significant decrease in weight and enhanced gross lesions. All infected layers showed positive results for virus shedding; however, the pattern of virus shedding was different, with layers of VC group showing more pronounced virus excretion than the layers in the NVC group. In addition, layers of VC group showed significantly reduced antibody responses and interferon gene expression when compared with the layers of NVC group. The present study revealed that MS vaccine could facilitate replication of avian influenza viruses and thus avian influenza virus infections can be worse after MS vaccination, especially in AIV-endemic areas.

Mycoplasma Synoviae Infection in Layers: Diagnosis and Control Measures – A Review

“…In general, this bacteria causes subclinical respiratory infection (Kleven 2008). However, it may evolve progressively and will induce air sacculitis lesions, particularly when mycoplasma infection is exacerbated by other pathogens such as Newcastle disease virus (NDV), IBV and avian infl uenza virus (AIV), or when birds are infected with highly virulent M. synoviae strains (Lockaby et al, 1999;Santos et al, 2014;Umar et al, 2017). Experimental infection of breeder hens with virulent M. synoviae strain can induce EAA eggs production from the sixth day aft er a single intra-tracheal inoculation if preceded by an infection with IBV.…”

“…Moreover, M. synoviae vaccines may predispose poultry to severe viral and bacterial infections. Immunosuppressed layer hens have been shown high levels of viral particles in tissues caused by AIV, subtype H9N2 (Kwon et al, 2008;Umar et al, 2017). Similarly, immunosuppression can increase the susceptibility of hens to bacteria and viruses infections (Subler et al, 2006).…”

“…Indeed, M. synoviae vaccine strains can modify AIV replication and immune responses. Furthermore, live vaccines can act as a complicating factor during respiratory co-infection in layers, which may subsequently lead to vaccination strategies advance against poultry respiratory pathogens, in general (Umar et al, 2017).…”

Molecular characterization and antimicrobial susceptible profiles of Thai mycoplasma synoviae and immune response chickens received live mycoplasma synoviae vaccine

“…The disease control strategy of M. synoviae infection in breeder, layer and broiler flocks normally consists of three general approaches; pathogen-free flocks' maintenance, medication, and vaccination (Umar et al, 2017). Besides, the successful strategy requires the early detection of disease and the corrected assessments of risks in poultry farms (Stipkovits and Kempf, 1996).…”