Virulence evaluation of Israeli Marek's disease virus isolates from commercial poultry using their meq gene sequence.

Fifty-seven Gallid alphaherpesvirus 2 (GaHV-2) isolates, collected during a 30-year period (1990-2019) from commercial poultry flocks affected by Marek's disease (MD), were molecularly characterised. The GaHV-2 meq gene was amplified and sequenced to evaluate the virus virulence, based on the number of PPPPs within the proline-rich repeats (PRRs) of its transactivation domain. The present illustration of virus virulence evaluation on a large scale of field virus isolates by molecular analysis exemplifies the practical benefit and usefulness of the molecular marker in commercial GaVH-2 isolates.

Marek's disease in genetically susceptible Cochin chickens in Italy: a case report.

The present study investigates an outbreak of classical Marek's disease (MD) in backyard Cochin chickens reared for hobby in Italy. Examined chickens showed spastic paralysis of the legs and at necropsy, enlargement and discoloration of the peripheral nerves and plexuses that matched microscopic A‑ and B‑ type MD lesions. Molecular analysis of the meq gene of the detected Gallid alphaherpesvirus 2 (GaHV‑2) strain, showed typical markers of low virulence and the strain shared the entire meq gene sequence with strains circulating in Italian backyard chickens.

The Complexity of Swine Caliciviruses. A Mini Review on Genomic Diversity, Infection Diagnostics, World Prevalence and Pathogenicity.

Caliciviruses are single stranded RNA viruses, non-enveloped structurally, that are implicated in the non-bacterial gastroenteritis in various mammal species. Particularly in swine, viral gastroenteritis represents a major problem worldwide, responsible for significant economic losses for the pig industry. Among the wide range of viruses that are the proven or suspected etiological agents of gastroenteritis, the pathogenicity of the members of Caliciviridae family is among the less well understood.

Epidemiology of Astrovirus, Norovirus and Sapovirus in Greek pig farms indicates high prevalence of Mamastrovirus suggesting the potential need for systematic surveillance.

Backround: Astrovirus, Norovirus and Sapovirus exhibit a wide distribution in swine pig herds worldwide. However, the association of porcine Astrovirus (PAstV), porcine Norovirus (PoNoV) and porcine Sapovirus (PoSaV) with disease in pigs remains uncertain. In this study, we investigated the prevalence of PAstV, PoNoV and PoSaV in Greek pig farms using both conventional RT-PCR and SYBR-Green Real-time RT-PCR in an effort to compare the sensitivity of the two methods.

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.

Israeli Pox Virus (IsrRAPXV) Infection in Juvenile Egyptian Fruit Bat (): Clinical Findings and Molecular Detection.

During 2019, five carcasses of juvenile Egyptian fruit bats () were submitted to the Kimron Veterinary Institute. These bats exhibited typical poxvirus like lesion plaques of different sizes on the skin, abdomen and the ventral side of the wings. Clinical and histopathological findings suggested a poxvirus infection.

Out of Sight, but Not Out of Mind: Aspects of the Avian Oncogenic Herpesvirus, Marek's Disease Virus.

Marek's disease virus is an economically important avian herpesvirus that causes tumors and immunosuppression in chickens and turkeys. The virus, disease, and vaccines have been known for more than 50 years, but as knowledge gaps still exists, intensive research is still ongoing. The understanding of MDV complexity can provide scientific insight in topics that cannot be experimented in humans, providing a unique model that is dually useful for the benefit of the poultry industry and for studying general herpesvirology.

A novel poxvirus isolated from an Egyptian fruit bat in Israel.

An Egyptian fruit bat (Rousettus aegyptiacus) from the Zoological Gardens, at Tel Aviv, Israel, showed pox-like clinical signs including vesicular and nodular skin lesions on the wings. Cell culture isolation, histopathology, electron microscopy and molecular analysis, revealed the presence of a novel bat poxvirus. Future research is needed to determine whether this virus can affect human health.

Molecular characterization of a Marek's disease virus strain detected in tumour-bearing turkeys.

Marek's disease (MD) is a lymphoproliferative disease caused by (GaHV-2), which primarily affects chickens. However, the virus is also able to induce tumours in turkeys, albeit less frequently than in chickens. This study reports the molecular characterization of a GaHV-2 strain detected in a flock of Italian meat-type turkeys exhibiting visceral lymphomas.

Marek's disease viruses circulating in commercial poultry in Italy in the years 2015-2018 are closely related by their meq gene phylogeny.

Marek's disease (MD) is a lymphoproliferative disease important to the poultry industry worldwide; it is caused by Gallid alphaherpesvirus 2 (GaHV-2). The virulence of GaHV-2 isolates has shifted over the years from mild to virulent, very virulent and very virulent +. Nowadays the disease is controlled by vaccination, but field strains of increased virulence are emerging worldwide.

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.

Study of the underlying mechanisms and consequences of pathogenicity differences between two in vitro selected G1-H9N2 clones originating from a single isolate.

The G1-H9N2 avian influenza virus (AIV) has caused significant economic losses in the commercial poultry industry due to reduced egg production and increased mortality. The field observations have shown that H9N2 viruses circulate and naturally mix with other pathogens and these simultaneous infections can exacerbate disease. To avoid an incorrect virus characterization, due to co-infection, isolates were purified by in vitro plaque assays.

A G1-lineage H9N2 virus with oviduct tropism causes chronic pathological changes in the infundibulum and a long-lasting drop in egg production.

Since 1997, G1-lineage H9N2 avian influenza viruses have been circulating in Asia and later on in the Middle East, and they have been associated to mild respiratory disease, drops in egg production and moderate mortality in chickens, in particular in the presence of concurrent infections. In this study, we investigated the importance of the G1-lineage H9N2 A/chicken/Israel/1163/2011 virus as a primary pathogen in layers, analyzing its tropism and binding affinity for the oviduct tissues, and investigating the long-term impact on egg production. Besides causing a mild respiratory infection, the virus replicated in the oviduct of 60% of the hens causing different degrees of salpingitis throughout the organ, in particular at the level of the infundibulum, where the detection of the virus was associated with severe heterophilic infiltrate, and necrosis of the epithelium.

Middle East respiratory syndrome coronavirus specific antibodies in naturally exposed Israeli llamas, alpacas and camels.

Thus far, no human MERS-CoV infections have been reported from Israel. Evidence for the circulation of MERS-CoV in dromedaries has been reported from almost all the countries of the Middle East, except Israel. Therefore, we aimed to analyze MERS-CoV infection in Israeli camelids, sampled between 2012 and 2017.

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.

Differential amplification of Marek's disease CVI988 vaccine and of wild-type isolates from organs of commercial chickens using single or duplexed probes in real-time PCR.

The differentiation of Marek's disease virus (MDV)-infected and vaccinated animal (DIVA) test, based on the MDV pp38 gene was described by Baigent et al. [(2016). Real-time PCR for differential quantification of CVI988 vaccine and virulent MDV strains.

Synergy or interference of a H9N2 avian influenza virus with a velogenic Newcastle disease virus in chickens is dose dependent.

Field observations indicate that the impact of velogenic Newcastle disease virus (vNDV) is more severe in countries with concomitant circulation of low pathogenicity avian influenza virus, as is the case in the Middle East, in particular in Israel, where H9N2 and NDV are endemic. In our study, we evaluated how the exposure of chickens to an H9N2 challenge either favours or interferes with a subsequent vNDV infection and its transmission to sentinels. For this purpose, single vNDV and sequential H9/NDV challenges were performed with increasing doses of vNDV (10-10 EID).

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.

The avian flavivirus Turkey Meningoencephalitis Virus (TMEV) causes a neuroparalytic disease of commercial turkeys, expressed in paresis, incoordination, drooping wings and mortality that is controlled by vaccination. The molecular diagnosis using brain tissue RNA has now been upgraded by the development of a diagnostic dual-gene multiplex real-time PCR targeting the envelope and the non-structural NS5 gene, increasing the sensitivity by 10-100-fold compared to the previously existing assays. Based on the recent complete sequences of five TMEV isolates we have now developed a Differentiating Infected from Vaccinated Animals (DIVA) assay, to distinguish between wild-type TMEV strains and the vaccine virus.

Antigenic Cartography of H9 Avian Influenza Virus and Its Application to Vaccine Selection.

Vaccination is frequently used as a control method for the H9 subtype of low pathogenicity avian influenza virus (AIV), which is widespread in Asia and the Middle East. One of the most important factors for selecting an effective vaccine strain is the antigenic match between the hemagglutinin protein of the vaccine and the strain circulating in the field. To demonstrate the antigenic relationships among H9 AIVs, with a focus on Israeli H9 isolates, antigenic cartography was used to develop a map of H9 AIVs.

Molecular Epidemiology and Evolution of Influenza Viruses Circulating within European Swine between 2009 and 2013.

Unlabelled: The emergence in humans of the A(H1N1)pdm09 influenza virus, a complex reassortant virus of swine origin, highlighted the importance of worldwide influenza virus surveillance in swine. To date, large-scale surveillance studies have been reported for southern China and North America, but such data have not yet been described for Europe. We report the first large-scale genomic characterization of 290 swine influenza viruses collected from 14 European countries between 2009 and 2013.

Genome-wide mapping of DNase I hypersensitive sites and association analysis with gene expression in MSB1 cells.

DNase I hypersensitive sites (DHSs) mark diverse classes of cis-regulatory regions, such as promoters and enhancers. MSB-1 derived from chicken Marek's disease (MD) lymphomas is an MDV-transformed CD4+ T-cell line for MD study. Previously, DNase I HS sites were studied mainly in human cell types for mammalian.

Differential diagnosis of fowlpox and infectious laryngotracheitis viruses in chicken diphtheritic manifestations by mono and duplex real-time polymerase chain reaction.

Infectious laryngotracheitis virus (ILTV) and fowlpox virus (FPV) cause diphtheritic lesions in chicken tracheas and can simultaneously infect the same bird. A differential molecular diagnostic test, the duplex real-time polymerase chain reaction, is now reported using ILTV and FPV vaccine viruses and clinical samples from chickens, either uninfected or naturally infected with ILTV or FPV, or with both viruses. The dual virus amplification by real-time polymerase chain reaction was demonstrated to behave similarly to monoplex amplification, in spite of the fact that the real-time exponential amplification plots of the vaccine viruses were more illustrative than those of the clinical samples.