Genomic analysis of an effective lentiviral vaccine-attenuated equine infectious anemia virus vaccine EIAVFDDV13

Abstract

Chinese equine infectious anemia virus (EIAV) attenuated vaccine is the first lentiviral vaccine with a successful application. In order to understand the correlation of viral genomic mutations with viral attenuation and with induced immunoprotective properties, we analyzed the proviral genome sequences of the EIAV-attenuated vaccine strain EIAV(FDDV13) (EIAV fetal donkey dermal cell-adapted vaccine) and its highly virulent parental strain EIAV(LN40). The sequences of these strains were compared with those of the major foreign EIAV strains. The results indicated a large genetic distance between the Chinese EIAV strain and the major EIAV strains in America and Japan. The Chinese strains belong to an independent phylogenetic branch. The divergence between the entire genome of the Chinese strains and that of other major EIAV strains is approximately 23%. The divergence rate in LTR is over 14%, whereas that in each open reading frame is over 20%. The gp90 exhibited a divergence of 35% in its nucleotide sequence and 40% in its amino acid sequence. The present study found that after long-term passage in vitro, EIAV(FDDV13) has accumulated many stable substitution mutations in each gene. These mutations at multiple sites in multiple genes of the vaccine strain, especially the conserved mutations, provide important references for further understanding the attenuation mechanism of Chinese EIAV-attenuated vaccine and the immunoprotection mechanism of lentiviral vaccines.

Unique evolution characteristics of the envelope protein of EIAVLN40, a virulent strain of equine infectious anemia virus

“…Previous studies proposed that during persistent EIAV infection, immunological pressure, particularly from neutralizing antibody, is the major factor that promotes variations and antigenic drift of the Env [19]. It has been known that the Chinese EIAV LN40 is in a different phylogenetic branch from other published EIAV strains (EIAV Wyoming , V70, V26, and EIAV PA ) [35]. To fully understand the characteristics of mutations of EIAV LN40 gp90 gene and the relationship between these mutations and the disease, both lethal and non-lethal doses of EIAV LN40 were used to infect horses in this study.…”

“…The Japanese virulent strain is evolutionally similar to EIAV Wyoming . The genome of the Chinese virulent strain is different from those of these two strains by about 23%, the variation of Env is as high as 35.9-40.6%, and the difference between EIAV PA SU is greater than 40% [35]. Indepth analysis and comparison of EIAV virulent strains that have obvious differences in their genomes but very similar biological properties can help us to better understand the relationship between gene characteristics and functions of EIAV.…”

Cloning, expression and preliminary crystallographic analysis of the equine infectious anaemia virus (EIAV) gp45 ectodomain

“…Briefly, the HR1 and HR2 regions were connected by a GGSGG (GGAGGTTCCGGCGGG) linker and the disulfidebond loop between HR1 and HR2 was replaced by this linker. HR1 and HR2 were amplified by polymerase chain reaction (PCR) using the gene encoding full-length EIAV gp140 (gp90 plus gp45) from the EIAV LN40 strain (Qi et al, 2010) as a template. The forward primer for gp45-HR1 was 5 0 -TACTTCCAATCCAATGCCGATAGTGTA-CAAAAT-3 0 and the reverse primer was 5 0 -CCCGCCGGAACCT-CCAATCAAATTAAATGT-3 0 .…”

“…The crystal structure of simian immunodeficiency virus (SIV) gp41 (PDB code 1qbz; Roux & Taylor, 2007) contains the longest helices. To solve the structure of EIAV gp45, we cloned, expressed and crystallized the ectodomain of EIAV gp45 from the EIAV LN40 strain (Qi et al, 2010). To facilitate purification, a short stretch of the disulfide-bond loop region was omitted and most of the sequences predicted within the helix region were included in our construct (Fig.…”

Equine infectious anemia virus in Japan: Viral isolates V70 and V26 are of North American not Japanese origin

“…These strains have been Veterinary Microbiology 174 (2014) 276-278 described as of Japanese origin with either a virulent (V70) or an attenuated (V26) phenotype (Pang et al, 1997;Zheng et al, 1997aZheng et al, ,b, 2000a. As a result of these published reports V70 and V26 have been included as ''Japanese'' or ''Asian'' viruses in a number of phylogenetic and epidemiological studies published in Veterinary Microbiology (Capomaccio et al, 2012b) and other journals (Asseged et al, 2012;Boldbaatar et al, 2013;Capomaccio et al, 2012a,b;Cappelli et al, 2011;Leroux et al, 2004;Nagarajan and Simard, 2007;Qi et al, 2010;Spyrou et al, 2005;Wang et al, 2011a,b).…”