Description

Description: Feline leukemia virus (FeLV) is a widespread pathogen of the domestic feline and (Cornell University, 2016) and was first described in 1964. It is an RNA virus in the subfamily Oncovirinae belonging to the Retroviridae family. The FeLV genome contains three genes coding for the structural proteins of the virus; the group specific antigen (gag) gene, including p27; the polymerase (pol) gene coding for the reverse transcriptase, protease and integrase; and the envelope (env) gene coding for the glycoprotein gp70 and the transmembrane protein p15 E (Coffin, 1979). The total genome is ~9.6kbp. Following synthesis of a DNA copy of the viral RNA genome, it integrates into the genome of the target cell as a provirus. This provirus remains in the genome of the cell for the life span of the cell and, upon cellular division, the viruses bud from the membrane of the infected cell, undergoing the final phase of maturation with cleavage of the Pr65 group antigen (Gag) precursor into the mature structural proteins p15 matrix (MA), p27 capsid (CA) and p10 nucleocapsid (NC). FeLV assembles at the plasma membrane. The precursor of the viral structural proteins Pr65Gag is thought to attach to the underside of the membrane. Once bound, the Pr65Gag proteins multimerise, triggering the membrane to bend around the forming core. Env proteins associate with the nascent particle through their co-localization on the membrane until an immature particle is formed. A scission event then takes place, releasing the immature virion, at which time the viral protease cleaves Pr65Gag into distinct matrix (MA), capsid (CA) and nucleocapsid (NC) proteins. As they bud from the infected cell, nascent virions acquire the envelope glycoprotein Env, comprising the surface (SU) glycoprotein gp70 and transmembrane (TM) protein p15E. Gp70 is the target for neutralizing antibodies in recovered felines and is an essential component of FeLV vaccines (Willett and Hosie, 2013). The prevalence of FeLV in felines has decreased significantly in the past 25 years since the development of an effective vaccine and more accurate testing procedures (Cornell University, 2016). The majority of in-practice tests for FeLV detect viral antigen (capsid protein p27) in blood, plasma or serum. P27 is the most abundant viral protein in the plasma of viremic felines. Its utility as a diagnostic marker for FeLV viremia is only possible because felines do not appear to respond serologically to the protein, an observation that has led to speculation that felines may be largely immunologically tolerant to p27 through exposure to endogenously expressed FeLV Gag (Willett and Hosie, 2013). Felines that clear infectious virus from the plasma will be negative by virus isolation, ELISA, immunochromatography, and Immunofluorescence, but will remain positive by provirus PCR and are considered regressively infected. A small proportion (2-3%) of felines remains positive by ELISA and immunochromatography although no infectious virus can be isolated from plasma. These felines have foci of infection outside the bone marrow from which soluble p27 is released into the circulation; such felines are potential sources of infection (Lutz et al., 1980c; Regina Hofmann-Lehmann et al., 2018).

Additional Text

Purification

Protein A purified

Antibody Clonality

Monoclonal