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Small Ruminant Lentiviruses: Genetic Variability, Tropism and Diagnosis
Laboratory of Virology, Genetics and Molecular Biology, FES-Cuautitlán, UNAM C-4 Veterinary, Cuautitlán Izcalli, State of Mexico 54714, Mexico
Institute of Agrobiotechnology, CSIC-UPNA-Government of Navarra, Ctra. Mutilva Baja s/n, Navarra 31192, Spain
Current address: Game and Fish Research Centre, University of Córdoba, Ctra Nacional IV-a Km 396, Córdoba 14071, Spain
* Author to whom correspondence should be addressed.
Received: 20 February 2013; in revised form: 9 April 2013 / Accepted: 12 April 2013 / Published: 23 April 2013
Abstract: Small ruminant lentiviruses (SRLV) cause a multisystemic chronic disease affecting animal production and welfare. SRLV infections are spread across the world with the exception of Iceland. Success in controlling SRLV spread depends largely on the use of appropriate diagnostic tools, but the existence of a high genetic/antigenic variability among these viruses, the fluctuant levels of antibody against them and the low viral loads found in infected individuals hamper the diagnostic efficacy. SRLV have a marked in vivo tropism towards the monocyte/macrophage lineage and attempts have been made to identify the genome regions involved in tropism, with two main candidates, the LTR and env gene, since LTR contains primer binding sites for viral replication and the env-encoded protein (SU ENV), which mediates the binding of the virus to the host’s cell and has hypervariable regions to escape the humoral immune response. Once inside the host cell, innate immunity may interfere with SRLV replication, but the virus develops counteraction mechanisms to escape, multiply and survive, creating a quasi-species and undergoing compartmentalization events. So far, the mechanisms of organ tropism involved in the development of different disease forms (neurological, arthritic, pulmonary and mammary) are unknown, but different alternatives are proposed. This is an overview of the current state of knowledge on SRLV genetic variability and its implications in tropism as well as in the development of alternative diagnostic assays.
Keywords: SRLV; CAEV; VMV; genetic variability; tropism; diagnosis
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Ramírez, H.; Reina, R.; Amorena, B.; Andrés, D.D.; Martínez, H.A. Small Ruminant Lentiviruses: Genetic Variability, Tropism and Diagnosis. Viruses 2013, 5, 1175-1207.
Ramírez H, Reina R, Amorena B, Andrés DD, Martínez HA. Small Ruminant Lentiviruses: Genetic Variability, Tropism and Diagnosis. Viruses. 2013; 5(4):1175-1207.
Ramírez, Hugo; Reina, Ramsés; Amorena, Beatriz; Andrés, Damián D.; Martínez, Humberto A. 2013. "Small Ruminant Lentiviruses: Genetic Variability, Tropism and Diagnosis." Viruses 5, no. 4: 1175-1207.