Nguyen Thi Dieu THUY, Nguyen Thi THU, Nguyen Giang SON, Le Thi Thu HA, Do Vo Anh KHOA

Genetic Analysis of the ORF7 Gene in Vietnamese Porcine Reproductive and Respiratory Syndrome Virus (PRRSV)

Domuz reprodüktif ve respiratorik sendromu (DRRS), dünya çapında domuz endüstrisi için ekonomik olarak en fazla kayba neden olan hastalıklardan birisidir. Vietnamda, 2008-2012 boyunca 36 sahadaki DRRSV izolatlarının 372-bp komple nükleer kılıf proteinini (N-protein) kodlayan gen (ORF7) dizilimi yapıldı ve DSRRVnin belli aşıları ve yayınlanmış türleri ile karşılaştırıldı. Otuzaltı 36 tür arasında, ORF7nin nukleotid dizilim benzerliği (nt) ve aminoasit (aa) özdeşliği en yüksek olup, %95.1 ile 100 arasında değişiklik gösterdi. Bu izolatlar, VR2332 (nt %91.9-94.3, aa %92.6-96.7) ve LV (nt %62.7-65.3, aa %58.5-60.1) ile benzerlik taşıyordu. Quang Nam yöresindeki 2007 DRRS salgınında QN07 (nt %96.2-99.1, aa %96.7-99.1) ile 1995te Çinde izole edilen CH-1a (nt %93.0-96.2, aa %92.6-95.9) ve Çinde 2006da izole edilen yüksek patojenik tür JXA (nt %96.7-99.7, aa %97.5-100) ile daha yüksek düzeyde benzerlikler vardı. Prototip tür VR-2332ye göre, her iki değişkende ve N-protein amino asit diziliminin korunaklı bölgelerinde yerleşik 6 aa mutasyonları, 36 izolatın çoğunda ve Çindeki yüksek patojenik DRRSV türlerinde tespit edildi. Dizilim analizleri sonuçları, Vietnamda 2008-2012 boyunca izole edilen DRRSVlerin Kuzey Amerikan Genotipi olarak sınıflandırıldığını gösterdi. Filogenetik ağaç, ek olarak 36 DRRSV izolatlarını, diğer yakın zamanda bildirilen Vietnam türlerini, yüksek patojenik Çin türlerini ve JXA1-R aşı türlerini aynı kümede topladı ve prototip tür (VR-2332) ve Ingelvac MLV/Besta aşı türlerinden ayrıldı. Sirkülasyondaki DRRSV türlerindeki ORF7nin genetik karakterizasyonu sonucu, Vietnamdaki DRRSnin etkili izleme ve kontrol stratej ilerinin gelişimine yardım edebilir.

Vietnam Domuz Reprodüktif ve Respiratorik Sendrom Virüsü (DRRSV) ORF7 Geninin Genetik Analizi

Porcine reproductive and respiratory syndrome (PRRS) is one of the most economically devastating diseases for the swine industry worldwide. The 372-bp complete nuclear capsid protein (N-protein) encoding gene (ORF7) of 36 field PRRSV isolates from Vietnam collected during 2008- 2012 were sequenced and compared with certain vaccines and published strains of PRRSV. The ORF7 nucleotide sequence (nt) similarity and amino acid (aa) identity among 36 strains showed the highest and ranged from 95.1 to 100%. These isolates shared similarities with VR-2332 (nt 91.9-94.3%, aa 92.6-96.7%) and LV (nt 62.7-65.3%, aa 58.5-60.1%). There were higher level of similarity with QN07 (nt 96.2-99.1%, aa 96.7-99.1%) from the 2007 PRRS outbreak in Quang Nam province, CH-1a (nt 93.0-96.2%, aa 92.6-95.9%) isolated in China in 1995 and JXA1 (nt 96.7-99.7%, aa 97.5-100%), the highly pathogenic strain from China isolated in 2006. Six aa mutations located in both variable and conserved regions of N-protein amino acid sequence were detected in most of the 36 isolates and highly pathogenic PRRSV strains in China in comparison to the prototype strain VR-2332. Results of sequence analyses indicated that PRRSVs isolated in Vietnam during 2008-2012 were classified as North American genotype. Phylogenetic tree also clustered those 36 PRRSV isolates, other recently reported Vietnamese strains, highly pathogenic Chinese strains and JXA1-R vaccine strain in the same cluster and separated from the prototype strain (VR-2332) and Ingelvac MLV/Besta vaccine strains. The result on genetic characterization of ORF7 of circulating PRRSV strains may assist the development of effective strategies for monitoring and controlling PRRS in Vietnam.

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