Development of duplex dual-gene and DIVA real-time RT-PCR assays and use of feathers as a non-invasive sampling method for diagnosis of Turkey Meningoencephalitis Virus

A two-branched upgrade to demonstrate ITV transmission by blood-sucking insects

The enveloped flavivirus Israel turkey meningoencephalitis virus (ITV) causes a neuroparalytic disease in adult turkeys leading to morbidity and mortality. This study reevaluates the role of blood-sucking insects in the transmission of ITV. We demonstrate the crucial importance of two factors in detecting viruses carried by blood-sucking insects: first, enhanced molecular detection of ITV in insects by nested qRT-PCR and second, collection and maintenance of live insects until their molecular examination. These upgrades allowed overcoming the small virus quantities contained in the insects and detecting ITV for the first time in field-collected Culex pipiens.

Biotic concerns in generating molecular diagnosis matrixes for 4 avian viruses with emphasis on Marek's disease virus

The great advance in the field of diagnosis of avian viruses is reflecting the highly sophisticated molecular assays of the human and general virology in providing highly sensitive and fast methods of diagnosis. The present review will discuss the biotic factors and the complexities that became evident with the evolution of the novel molecular diagnostic assays with emphasis on 4 avian viruses, chicken anemia, infectious laryngotracheitis, turkey meningoencephalitis, but mainly on Marek's disease virus. To create a biologically meaningful diagnosis, attention should be dedicated to various biotic factors and not only of the diagnostic assay. Included among the important factors are, (a) the sample examined and the sampling strategy, (b) the outcomes of the pathogen amplification ex vivo, (c) the sampling time and its reflection on the disease diagnosis, (d) the impact of simultaneous multiple virus-infections regarding the ability to demonstrate all pathogens and inter- and intra-interactions between the pathogens. A concerted consideration of the relevant factors and the use of advanced molecular diagnostic assay would yield biologically significant diagnosis in real-time that would beneficiate the poultry industry.

Mosquito-borne epornitic flaviviruses: an update and review

West Nile Virus, Usutu virus, Bagaza virus, Israel turkey encephalitis virus and Tembusu virus currently constitute the five flaviviruses transmitted by mosquito bites with a marked pathogenicity for birds. They have been identified as the causative agents of severe neurological symptoms, drop in egg production and/or mortalities among avian hosts. They have also recently shown an expansion of their geographic distribution and/or a rise in cases of human infection. This paper is the first up-to-date review of the pathology of these flaviviruses in birds, with a special emphasis on the difference in susceptibility among avian species, in order to understand the specificity of the host spectrum of each of these viruses. Furthermore, given the lack of a clear prophylactic approach against these viruses in birds, a meta-analysis of vaccination trials conducted to date on these animals is given to constitute a solid platform from which designing future studies.

Monitoring the uptake of live avian vaccines by their detection in feathers

Protection against diseases caused by the avian viruses, Marek's disease, Infectious laryngotracheitis, chicken anemia and turkey meningoencephalitis is achieved by live vaccines. The application quality is important to assure proper uptake in commercial flocks. We describe a novel evaluation method for the vaccination process by sequential monitoring the vaccine viruses in feathers. Feather collection is easy, non-invasive and non-lethal for the birds, therefore advantageous for monitoring purposes. To demonstrate the vaccine virus presence, an innovative assay of nested real-time amplification was approached because vaccine viruses presence in vivo is less abundant comparing to virulent wild-type isolates. The Marek's disease virus vaccine virus, Rispens/CVI988, in feathers of commercial flock was detected from 4 to 7 days and for at least 3 months post-vaccination, until the survey stopped. As the drinking water route was newly adopted for Infectious laryngotracheitis vaccination, one or two vaccine doses/bird were administered. The virus uptake was detected in feathers between 2 and 20 days-post-vaccination. With a doubled vaccine dose the positivity bird rate was higher. For the first time the chicken anemia vaccine virus presence in chicken feathers was demonstrated between 14 and 35 days-post-vaccination. No previous studies were available, thus in parallel to feathers the vaccine virus was demonstrated in the livers and spleens. The turkey meningoencephalitis vaccine virus uptake in turkey feather-pulps is even more innovative because this is the first turkey virus amplified from feather-pulps. The vaccine virus presence resemble the kinetics of the other 3 viruses, 3-21 days-post-vaccination. Detecting the specific antibodies following vaccination possessed a lower sensitivity than vaccine virus demonstration in feathers. In summary, the presented assay can be adopted for the quality evaluation of the vaccination process in poultry.