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Molecular detection, epidemiology, and genetic characterization of novel European field isolates of equine infectious anemia virus.

ABSTRACT: The application of molecular diagnostic techniques along with nucleotide sequence determination to permit contemporary phylogenetic analysis of European field isolates of equine infectious anemia virus (EIAV) has not been widely reported. As a result, of extensive testing instigated following the 2006 outbreak of equine infectious anemia in Italy, 24 farms with a history of exposure to this disease were included in this study. New PCR-based methods were developed, which, especially in the case of DNA preparations from peripheral blood cells, showed excellent correlation with OIE-approved agar gel immunodiffusion (AGID) tests for identifying EIAV-infected animals. In contrast, the OIE-recommended oligonucleotide primers for EIAV failed to react with any of the Italian isolates. Similar results were also obtained with samples from four Romanian farms. In addition, for the first time complete characterization of gag genes from five Italian isolates and one Romanian isolate has been achieved, along with acquisition of extensive sequence information (86% of the total gag gene) from four additional EIAV isolates (one Italian and three Romanian). Furthermore, in another 23 cases we accomplished partial characterization of gag gene sequences in the region encoding the viral matrix protein. Analysis of this information suggested that most Italian isolates were geographically restricted, somewhat reminiscent of the "clades" described for human immunodeficiency virus type 1 (HIV-1). Collectively this represents the most comprehensive genetic study of European EIAV isolates conducted to date.

SUBMITTER: Cappelli K

PROVIDER: S-EPMC3020406 | biostudies-literature | 2011 Jan

REPOSITORIES: biostudies-literature

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Molecular detection, epidemiology, and genetic characterization of novel European field isolates of equine infectious anemia virus.

Cappelli Katia K Capomaccio Stefano S Cook Frank R FR Felicetti Michela M Marenzoni Maria Luisa ML Coppola Giacomo G Verini-Supplizi Andrea A Coletti Mauro M Passamonti Fabrizio F Passamonti Fabrizio F

Journal of clinical microbiology 20101117 1

The application of molecular diagnostic techniques along with nucleotide sequence determination to permit contemporary phylogenetic analysis of European field isolates of equine infectious anemia virus (EIAV) has not been widely reported. As a result, of extensive testing instigated following the 2006 outbreak of equine infectious anemia in Italy, 24 farms with a history of exposure to this disease were included in this study. New PCR-based methods were developed, which, especially in the case o ...[more]

PMID: 21084503

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Project description:The equine infectious anemia virus (EIAV) attenuated vaccine was developed by long-term passaging of a field-isolated virulent strain in cross-species hosts, followed by successive cultivation in cells in vitro To explore the molecular mechanism underlying the evolution of the EIAV attenuated vaccine, a systematic study focusing on long-terminal-repeat (LTR) variation in numerous virus strains ranging from virulent EIAV to attenuated EIAV was performed over time both in vitro and in vivo Two hypervariable regions were identified within the U3 region in the enhancer region (EHR) and the negative regulatory element (NRE) and within the R region in the transcription start site (TSS) and the Tat-activating region (TAR). Among these sites, variation in the U3 region resulted in the formation of additional transcription factor binding sites; this variation of the in vitro-adapted strains was consistent with the loss of pathogenicity. Notably, the same LTR variation pattern was observed both in vitro and in vivo Generally, the LTR variation in both the attenuated virus and the virulent strain fluctuated over time in vivo Interestingly, the attenuated-virus-specific LTR variation was also detected in horses infected with the virulent strain, supporting the hypothesis that the evolution of an attenuated virus might have involved branching from EIAV quasispecies. This hypothesis was verified by phylogenetic analysis. The present systematic study examining the molecular evolution of attenuated EIAV from EIAV quasispecies may provide an informative model reflecting the evolution of similar lentiviruses.IMPORTANCE The attenuated EIAV vaccine was the first lentiviral vaccine used to successfully control for equine infectious anemia in China. This vaccine provides an important reference for studying the relationship between EIAV gene variation and changes in biological characteristics. Importantly, the vaccine provides a model for the investigation of lentiviral quasispecies evolution. This study followed the "natural" development of the attenuated EIAV vaccine by use of a systematic analysis of LTR evolution in vitro and in vivo The results revealed that the increase in LTR variation with passaging was accompanied by a decrease in virulence, which indicated that LTR variability might parallel the attenuation of virulence. Interestingly, the attenuated-virus-specific LTR variation was also detected in virulent-strain-infected horses, a finding consistent with those of previous investigations of gp90 and S2 evolution. Therefore, we present a hypothesis that the evolution of the attenuated virus may involve branching from EIAV quasispecies present in vivo.

Dataset Information

Molecular detection, epidemiology, and genetic characterization of novel European field isolates of equine infectious anemia virus.

Publications

Molecular detection, epidemiology, and genetic characterization of novel European field isolates of equine infectious anemia virus.

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