1. An EIAV field isolate reveals much higher levels of subtype variability than currently reported for the equine lentivirus family.
- Author
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Craigo JK, Barnes S, Zhang B, Cook SJ, Howe L, Issel CJ, and Montelaro RC
- Subjects
- Animals, Antibodies, Viral immunology, Cross Reactions, Equine Infectious Anemia virology, Horses, Infectious Anemia Virus, Equine immunology, Infectious Anemia Virus, Equine isolation & purification, Pennsylvania, Protein Structure, Secondary, Sequence Homology, Amino Acid, Genetic Variation, Infectious Anemia Virus, Equine classification, Infectious Anemia Virus, Equine genetics, Viral Envelope Proteins genetics
- Abstract
Background: Equine infectious anemia virus (EIAV), a lentivirus that infects horses, has been utilized as an animal model for the study of HIV. Furthermore, the disease associated with the equine lentivirus poses a significant challenge to veterinary medicine around the world. As with all lentiviruses, EIAV has been shown to have a high propensity for genomic sequence and antigenic variation, especially in its envelope (Env) proteins. Recent studies have demonstrated Env variation to be a major determinant of vaccine efficacy, emphasizing the importance of defining natural variation among field isolates of EIAV. To date, however, published EIAV sequences have been reported only for cell-adapted strains of virus, predominantly derived from a single primary virus isolate, EIAVWyoming (EIAVWY)., Results: We present here the first characterization of the Env protein of a natural primary isolate from Pennsylvania (EIAVPA) since the widely utilized and referenced EIAVWY strain. The data demonstrated that the level of EIAVPA Env amino acid sequence variation, approximately 40% as compared to EIAVWY, is much greater than current perceptions or published reports of natural EIAV variation between field isolates. This variation did not appear to give rise to changes in the predicted secondary structure of the proteins. While the EIAVPA Env was serologically cross reactive with the Env proteins of the cell-adapted reference strain, EIAVPV (derivative of EIAVWY), the two variant Envs were shown to lack any cross neutralization by immune serum from horses infected with the respective virus strains., Conclusion: Taking into account the significance of serum neutralization to universal vaccine efficacy, these findings are crucial considerations towards successful EIAV vaccine development and the potential inclusion of field isolate Envs in vaccine candidates.
- Published
- 2009
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