Molecular Characterization and Phylogenetic Analysis of Marek's Disease Virus from Clinical Cases of Marek's Disease in Egypt

Abstract

In spite of the intensive vaccination policy against the Marek's disease virus (MDV) in Egypt, the Egyptian poultry flocks are still suffering from several tumor and paralysis cases. To investigate if MDV is the possible cause, feather follicle and tumor samples were collected during 2011 from 30 vaccinated chicken flocks experiencing nervous signs, emaciation, and tumor lesions. The samples were screened by PCR amplification of the meq full-length gene. Only five of 30 flocks were positive for MDV. Additionally, we sequenced meq from five samples and gL and gC from three samples. A phylogenetic tree was constructed using the deduced amino acid sequences of the meq gene. The sequence analysis revealed that most of the studied sequences showed > or = 98% identity to the very virulent European ATE and C12/130 isolates and the very virulent Chinese LMS, YA, WS03, and GX070060 MDV isolates. The two glycoproteins, gL and gC, displayed high similarity to the classical MDV strains published in the database regardless of their virulence.

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

“…At the moment in vivo studies are mandatory for an accurate inclusion of GaHV‐2 strains into one of the known pathotypes. The meq gene polymorphism is also useful to create epidemiological molecular linkages between various GaHV‐2 strains, according to the numerous studies that have been recently published from various countries: China (Tian et al, ; Yu et al, ; Zhang, Liu, Zhang, Shi, & Li, ), Poland (Woźniakowski & Samorek‐Salamonowicz, ), USA (Padhi & Parcell, ), Colombia (Lòpez‐Osorio et al, ), Egypt (Abdallah et al, ; Hassanin, Abdallah, & El‐Araby, ), India (Gupta, Deka, & Ramneek, ; Prathibha, Sreedevi, Vinod Kumar, & Srilatha, ; Suresh, Johnson Rajeswar, Sukumar, Harikrishnan, & Srinivasan, ) and Japan (Abd‐Ellatieff et al, ).…”

Th1 and Th2 Cytokines Activity during Transformation and Lymphoma Formation Stage in Chicken Naturally Infected with Marek's disease virus.

“…Spleen was used to obtain target cDNA, as it was known that spleen harbor all stages of the MDV life cycle (Baigent and Davison, 2004) and plays an important role in elicitation of immune responses. Conventional PCR for the detection of MDV-meq gene from spleen and other visceral organs DNA preparations using previously published specific primer (Hassanin et al, 2013) was done for initial MDV screening. The PCR amplification was performed in a 50 μl volume containing 2 μl of DNA, 4 μl of dNTP, 1 μl (10 μMol) of each primer, 5 μl 10x Ex Taq buffer, 0.25 μl Ex Taq polymerase (Takara, Kyoto, Japan), and 36.75 μl distilled water.…”

Identification and Characterization of Marek’s Disease Virus Serotype 1 Using Molecular Approaches

“…Pengendalian penyakit Marek di peternakan ayam komersial dilakukan melalui program vaksinasi sejak tahap penetasan menggunakan beberapa macam tipe vaksin seperti herpesvirus of turkey (HVT), Gallid Herpesvirus 3 (GaHV3) maupun MDV-1 atenuasi (Bublot & Sharma 2004). Meskipun kasus penyakit Marek dapat dikendalikan dengan program vaksinasi, namun laporan kejadian kasus masih sering terjadi di lapangan karena vaksinasi tidak 100% efektif mencegah infeksi virus di lapangan (Arulmozhi et al 2011;Gong et al 2013;Hassanin et al 2013). Penerapan program vaksinasi juga diduga memicu terjadinya evolusi virus MDV-1 menjadi lebih patogen (Gimeno 2008).…”

“…Marker atenuasi motif 132 bp repeats region masih digunakan dalam beberapa penelitian (Doosti & Golshan 2011;Kalyani et al 2011), namun banyak beberapa penelitian lainnya telah menggunakan marker gen lain seperti meq, ICP4, gB dan lain-lainnya (Handberg et al 2001;Jwander et al 2012;Hassanin et al 2013). Gen meq menjadi prioritas untuk identifikasi virus MDV-1 karena peran pentingnya dalam mengkode protein transaktivator dalam pembentukan sel tumor.…”

“…Demikian juga, Murata et al (2013) mengidentifikasi mutasi pada gen meq pada isolat MDV-1 asal Jepang yang diduga berkaitan dengan proses transaktivasinya. Kemudian, Hassanin et al (2013) melakukan analisis sekuen gen meq, gL dan gC pada sampel asal peternakan petelur komersial di Mesir yang sudah divaksinasi. Hasil analisisnya secara molekuler pada gen meq menunjukkan tingkat homologi yang tinggi dengan virus very virulent asal Eropa dan Cina sedangkan untuk gen gL dan gC mempunyai similaritas yang tinggi terhadap strain klasik.…”