title: Emergence of new virulent rabbit hemorrhagic disease virus strains in Saudi Arabia.
abstract: Rabbit hemorrhagic disease is an acute fatal highly contagious viral infectious disease that causes high losses among rabbitries. The disease was first reported in China in 1984 and later on in Saudi Arabia in 1996. The aim of this study was to investigate the emergence and pathogenicity of new rabbit hemorrhagic disease virus (RHDV) strains in Saudi Arabia. The pathogenicity was confirmed by inoculation in susceptible rabbits. Three RHDV strains were detected by reverse transcriptase polymerase chain reaction (RT-PCR) using primers targeting VP60 capsid protein gene in infected rabbitries during 2012 and 2013. These strains clustered into two genetically distinct genogroups related to year of isolation (G2 and G3). All new Saudi Arabia viruses clustered with the European strains, while the old strains clustered with strains from China and America. Based on amino acids and nucleotide sequences, the Saudi Arabia strains (RHD/1/SA/2012, RHD/2/SA/2012, and RHD/3/SA /2013) had high identity with Mexico89, Ca11-ITA, and 00-13,FRA virus; on the other hand, there was a relatively high identity with Bahrain strain. The evolutionary relationship of Saudi RHDVs strains revealed significant nucleotides and amino acid substitutions in hypervariable region E, suggesting the emergence of new RHDVs circulating in Saudi Arabia rabbitries. These antigenic changes represented by the antigenic index might be a potential cause of vaccination failure and raises the need to review the vaccination strategies against RHD.
authors.affiliation: Department of Poultry Diseases, College of Veterinary Medicine, Kafrelsheikh University, Kafrelsheikh, Egypt.
authors.forename: Mahmoud M
authors.initials: MM
authors.lastname: Ismail
authors.affiliation: Department of Clinical Studies, College of Veterinary Medicine, King Faisal University, Al-Hufof, 31982, Saudi Arabia. mahmoudhassanain@yahoo.com.|Department of Avian and Rabbit Medicine, College of Veterinary Medicine, Zagazig University, Zagazig, 44511, Egypt. mahmoudhassanain@yahoo.com.
authors.forename: Mahmoud H A
authors.initials: MH
authors.lastname: Mohamed
authors.affiliation: Central Biotechnology Laboratory, College of Veterinary Medicine, King Faisal University, Al-Hufof, 31982, Saudi Arabia.|Department of Virology, Faculty of Veterinary Medicine, Cairo University, 12211, Giza, Egypt.
authors.forename: Ibrahim M
authors.initials: IM
authors.lastname: El-Sabagh
authors.affiliation: Department of Microbiology and Parasitology, College of Veterinary Medicine, King Faisal University, Al-Hufof, 31982, Saudi Arabia.
authors.forename: Mohamed A
authors.initials: MA
authors.lastname: Al-Hammadi
mesh_terms: D000818:Animals; D017250:Caliciviridae Infections / Q000662:veterinary* / Q000821:virology; D019143:Evolution, Molecular; D005838:Genotype; D017929:Hemorrhagic Disease Virus, Rabbit / Q000145:classification / Q000235:genetics* / Q000472:pathogenicity*; D010802:Phylogeny; D011817:Rabbits; D012529:Saudi Arabia; D017423:Sequence Analysis, RNA / Q000662:veterinary; D015678:Viral Structural Proteins / Q000235:genetics*; D014774:Virulence
chemical_list: D015678:Viral Structural Proteins; C081149:viral protein 60, rabbit hemorrhagic disease virus
keywords: Phylogeny; RHDV; RT-PCR; Saudi Arabia; Sequencing; VP60