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Yue-Zhi Lin,
Rong-Xian Shen,
Zhen-Ying Zhu,
Xi-Lin Deng,
Xue-Zhi Cao,
Xue-Feng Wang,
Jian Ma,
Cheng-Gang Jiang, Li-Ping Zhao,
Xiao-Ling Lv,
Yi-Ming Shao,
Jian-Hua Zhou
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ABSTRACT: The EIAV (equine infectious anemia virus) multi-species attenuated vaccine EIAV(DLV121) successfully prevented the spread of equine infectious anemia (EIA) in China in the 1970s and provided an excellent model for the study of protective immunity to lentiviruses. In this study, we compared immune responses induced by EIAV(DLV121) to immunity elicited by the virulent EIAV(LN40) strain and correlated immune responses to protection from infection. Horses were randomly grouped and inoculated with either EIAV(DLV121) (Vaccinees, Vac) or a sublethal dose of EIAV(LN40) (asymptomatic carriers, Car). Car horses became EIAV(LN40) carriers without disease symptoms. Two of the four Vac horses were protected against infection and the other two had delayed onset or reduced severity of EIA with a lethal EIAV(LN40) challenge 5.5 months post initial inoculation. In contrast, all three Car animals developed acute EIA and two succumbed to death. Specific humoral and cellular immune responses in both Vac and Car groups were evaluated for potential correlations with protection. These analyses revealed that although plasma viral loads remained between 10(3) and 10(5)copies/ml for both groups before EIAV(LN40) challenge, Vac-treated animals developed significantly higher levels of conformational dependent, Env-specific antibody, neutralizing antibody as well as significantly elevated CD4(+) T cell proliferation and IFN-γ-secreting CD8(+) T cells than those observed in EIAV(LN40) asymptomatic carriers. Further analysis of protected and unprotected cases in vaccinated horses identified that cellular response parameters and the reciprocal anti-p26-specific antibody titers closely correlated with protection against infection with the pathogenic EIAV(LN40). These data provide a better understanding of protective immunity to lentiviruses.
Antiviral research 08/2011; 92(2):292-304. · 3.61 Impact Factor
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ABSTRACT: Preliminary studies revealed that the gene of the gp45 transmembrane protein (TM) of the attenuated equine infectious anemia virus (EIAV) vaccine strain EIAV(FDDV13) had a high frequency of a premature stop codon at position 261W, which generated a 154-residue truncation at the C-terminus. EIAV(FDDV-TM36), a recombinant virus with the TM truncated at the intracytoplasmic (CT) domain due to the presence of a stop codon, was constructed based on EIAV(FDDV)3-8, which is a proviral derivative of the vaccine. EIAV(FDDV-TM36) had a significantly reduced replication capability compared to EIAV(FDDV)3-8 in equine or donkey monocyte-derived macrophages and a decreased ability to induce apoptosis. However, both viruses raised a similar plasma viral load in inoculated horses and did not induce clinical symptoms of EIA. To further compare the in vivo behavior between EIAV(FDDV-TM36) and EIAV(FDDV)3-8, inoculated horses were transiently immunosuppressed with dexamethasone. While three of the four horses inoculated with EIAV(FDDV)3-8 demonstrated significant increases in viral loads after the drug treatment, none of the four horses inoculated with EIAV(FDDV-TM36) showed a statistically increased plasma viral load. Significantly increased neutralizing antibody levels were also observed in the group of horses inoculated with EIAV(FDDV)3-8, but not EIAV(FDDV-TM36), after immunosuppression. Our results indicate that although the CT truncation of TM decreased viral replication in cultivated equine and donkey macrophages, the primary target cell of EIAV, and did not influence the plasma viral load of inoculated hosts, it weakened the potential pathogenicity of the vaccine. The host immunity is presumably responsible for the equal in vivo replication levels of viruses with either the CT-truncated or prototype TM.
Virus Research 06/2011; 158(1-2):235-45. · 2.94 Impact Factor
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Jian Ma,
Nan Shi,
Cheng-Gang Jiang,
Yue-Zhi Lin,
Xue-Feng Wang,
Shuai Wang,
Xiao-Ling Lv, Li-Ping Zhao,
Yi-Ming Shao,
Xian-Gang Kong,
Jian-Hua Zhou,
Rong-Xian Shen
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ABSTRACT: To investigate essential factors that determine the efficacy of vaccines against lentiviruses, an effective attenuated equine infectious anemia virus (EIAV) vaccine strain and a proviral derivative of the vaccine were compared with respect to differences in inducing protective immunity. Although these two strains replicated equally well in vitro and in vivo, the proviral strain induced significantly less protection from disease and infection caused by viral challenge and significantly lower specific neutralizing capability. These findings indicated that the proviral strain had lost the ability to stimulate immune protection compared to the parental vaccine strain. A further analysis of the envelope gp90 gene variation revealed that compared to the proviral strain, the vaccine strain displayed a wide sequence diversity in immunogen composition. Thus, we inferred that the differences in immunogen composition might be the major cause for the failure of the proviral derivative to elicit the immune protection induced by the parental strain.
Virology 02/2011; 410(1):96-106. · 3.35 Impact Factor
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ABSTRACT: Bovine parainfluenza virus type 3 (BPIV3) is one of the most important of the known viral respiratory pathogens of both young and adult cattle. However BPIV3 has not been detected or isolated in China prior to this study. In 2008, four BPIV3 strains were isolated with MDBK cells from cattle in China and characterized by RT-PCR, nucleotide sequence analysis, transmission electron microscope observation, hemadsorption and hemagglutination tests. Nucleotide phylogenetic analysis of partial hemagglutinin-neuraminidase (HN) gene for four isolates and the complete genome for the SD0835 isolate implicated that the four Chinese BPIV3 strains were distinct from the previously reported genotype A (BPIV3a) and genotype B (BPIV3b) and might be a potentially new genotype, which was tentatively classified as genotype C (BPIV3c). This is the first study to report the isolation and genetic characterization of BPIV3 from cattle in China.
Veterinary Microbiology 11/2010; 149(3-4):446-51. · 3.33 Impact Factor
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ABSTRACT: China experienced an outbreak of equine influenza during 2007-2008. Meanwhile, its neighbor countries, such as Mongolia, India and Japan, have also been affected by various influenza virus strains in each country. Phylogenetic analysis showed that the newly emerging Chinese strains belong to Florida sublineage clade 2, as well as the Indian strain Jammu-Katra/6/08 and the Mongolian strain Mongolia/1/08. All of these strains were derived from European strains of this clade, such as the Newmarket/1/07 and Cheshire/1/07 strains, but these were not related to Japanese strains isolated around the same time (Florida sublineage clade 1) or to Chinese strains isolated in the 1990s (European lineage). Some unique amino acid changes were found in the antigenic sites in Asian strains of Florida sublineage clade 2. Moreover, the loss of a glycosylation site was found in the Liaoning/9/08 strain. From these studies, we have determined that equine influenza viruses in China have evolved with some new characteristics during recent years, and this emphasizes the importance of continued equine influenza virus surveillance in China.
Archives of Virology 09/2010; 155(9):1425-32. · 2.11 Impact Factor
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ABSTRACT: The threshold hypothesis of attenuated lentiviral vaccine considers that the type of host response to infections of lentiviruses depends on the viral load. To evaluate the correlation between viral loads of the attenuated vaccine strain of equine infectious anemia virus (EIAV) and their effects to induce protective immunity, longitudinal plasma viral loads in groups of horses inoculated with either an attenuated EIAV vaccine strain (EIAV(DLV125)) or sub-lethal dose of an EIAV virulent strain (EIAV(LN40)) were compared. Similar levels of plasma viral loads ranging from 10(3)-10(5) copies/mL were detected from samples of these two groups of animals (P > 0.05) during 23 weeks post the inoculation. However, different responses to the challenge performed thereafter with lethal dose of the EIAV virulent strain were observed from the groups of horses inoculated with either EIAV(DLV125) or sub-lethal dose of EIAV(LN40). The protective efficiency was 67% (3 of 4 cases) and 0 (none of 2 cases), respectively. Our results implicate that the viral load of EIAV attenuated vaccine is not the primary factor, or at least not the solo primary factor, to determine the establishment of immune protection.
Bing du xue bao = Chinese journal of virology / [bian ji, Bing du xue bao bian ji wei yuan hui] 03/2010; 26(2):128-33.
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ABSTRACT: To disclose the potential roles of humoral immune response in the EIAV vaccine-induced protective immunity. In this study, major parameters of humoral immunity be compared between horses inoculated with the EIAV vaccine strain and the pathogenic virulent strain.
Experimental horses were randomly assigned into the group inoculated with the vaccine strain EIAV(DLV); (the vaccinated group) and the group inoculated with sub-morbigenous dose of virulent strain EIAV(Liao); (the inapparent infection group). Humoral immunity parameters, including binding endpoint titer and avidity index of antibodies to the envelop protein (Env) and the capsid protein (P26), and the conformation-dependent index of the Env antibody, were assayed and compared between these two groups by using ELISA. Neutralizing antibodies to the EIAV vaccine strain and a pathogenic strain were simultaneously detected by using plaque forming unite assay (PFU) and reverse transcriptase activity assay, respectively.
In general, all humoral parameters increased with a time-dependent manner in both the vaccinated and the inapparent infection group. However, significantly higher antibody activities for P26 binding endpoint titer and Env avidity index were detected in the vaccinated group within 2 months post infection (P<0.05). Furthermore, the conformation-dependent index of the Env antibody in the vaccinated group was significantly higher than that in the inapparent infection group throughout the entire observation period (P<0.05). The most dramatic difference between these experimental groups was in the raise of the neutralizing antibody. The antibody neutralizing both the vaccine strain EIAV(DLV); and a virulent strain EIAV(DLV34); was detected significantly earlier and in higher titers in vaccinated horses than in virulent strain-infected horses (P<0.01 for EIAV(FDDV); and P<0.05 for EIAV(DLV34);).
Statistically significant differences in EIAV-specific binding antibodies and the neutralizing antibody are detected between animals induced with the EIAV vaccine strain and the virulent strain. Importantly, the significantly early and strong responses in the neutralizing antibody and the conformation-dependent Env antibody induced by the vaccine implicate special roles these antibodies playing in EIAV vaccine-induced immune protection.
Xi bao yu fen zi mian yi xue za zhi = Chinese journal of cellular and molecular immunology 12/2009; 25(12):1079-83.
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ABSTRACT: To elucidate the function of the S2 gene in equine infectious anemia virus (EIAV) and its role in the attenuation of the Chinese attenuated EIAV vaccine strains, the S2 in the EIAV vaccine strain EIAV (FDDV) was reverse-mutated and the in vitro replication character of the resultant virus was evaluated. Based on the sequence variation of the S2 gene between the EIAV virulent strains and vaccine strains, all the four vaccine-specific sites in the S2 of an EIAV(FDDV) infectious clone, pFDDV3-8, were reverse-mutated to the sequences of the virulent strain EIAV(DV115). The reverse-mutated molecular clone pFDDVS2r1-3-4-5 was used to transfect fetal donkey dermal (FDD) cells for rescuing the derived virus vpFDDVS2r1-3-4-5. The production and replication of vpFDDVS2r1-3-4-5 in FDD cells were proved by RT-PCR, immune fluorescence assay and reverse transcriptase activity assay. Typical virons of EIAV were clearly observed under the electron microscopy. The parallel analysis of the dynamic replication of the reverse-mutated viral clone vpFDDVS2r1-3-4-5 and its parental virus vpFDDV3-8 showed that the virus with four reverse mutations in the S2 replicated only slightly slower than its parental vaccine strain in FDD cells. This result implicates that the mutations in the S2 of the EIAV vaccine strains did not significantly alter the viral replication in vitro. Further studies on the in vivo replication of the reverse-mutated viral clone are required for understanding the relationship between the S2 and the attenuated pathogenesis of EIAV attenuated vaccines.
Bing du xue bao = Chinese journal of virology / [bian ji, Bing du xue bao bian ji wei yuan hui] 07/2009; 25(4):309-15.
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Xue-Feng Wang,
Cheng-Gang Jiang,
Wei Guo,
We Xiang,
Xiao-Ling Lv, Li-Ping Zhao,
Feng-Long Wang,
Xian-Gang Kong,
Xiao-Yan Zhang,
Yi-Ming Shao,
Jian-Hua Zhou
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ABSTRACT: The donkey leukocyte-attenuated vaccine of equine infectious anemia virus (EIAV) was the first lentiviral vaccine that induced solid protection from the infection of virulent strains. To elucidate the mechanism of increased immunogenicity and attenuated virulence of the vaccine, the proviral genomic DNA of an EIAV vaccine strain, EIAV(DLV121) was analyzed and compared with the genome of a parental virulent strain EIAV(DV117). Full length viral genomic DNAs were amplified as two segments by LA-PCR and were cloned. Because of the genomic diversity of retroviral quasispecies, 10 full-length sequences of EIAV(DLV121) and 4 full-length sequences of EIAV(DV117) from randomly picked clones were analyzed. Results showed that the average length of the complete nucleotide sequence of EIAV(DLV121) was 8,236bp and EIAV(DV117) was 8,249bp, with the inter-strain diversity of 2.8%. As for individual genes between the vaccine and virulent strains, the differences in nucleotide sequence of S2, LTR and env were significantly higher than the other genes with the diversity of 4.1%, 3.7% and 3.1%, respectively. Considerable variations in deduced amino acid sequences were found in S2, S3 and env. The diversities were 10.4%, 5.6% and 4.8%, respectively. Furthermore, the LTR of EIAV(DLV121) consisted of at least 5 subtypes grouped by their nucleotide sequences. There were two additional N-linked glycosylation sites in the deduced amino acid sequence of EIAV(DV117) gp90 than that of EIAV(DLV121). Among glycosylation sites in the gp90 of virulent strain, 3 were found unique only in EIAV(DV117), of which 2 were located in the principle neutralizing domain (PND). In addition, there was one EIAV(DLV121) -specific glycosylation site, which was positioned in the PND, too. Taken together, it is clear that greatly increased genomic diversity exists in the EIAV vaccine strain, which provides important information for the further study on biological characters of the Chinese EIAV attenuated vaccine.
Bing du xue bao = Chinese journal of virology / [bian ji, Bing du xue bao bian ji wei yuan hui] 12/2008; 24(6):443-50.
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ABSTRACT: To develop a flow cytometry using (5-carboxyfluorescein diacetate succinmidyl ester, CFSE) to detect the proliferation of specific T lymphocytes from equine infectious anemia virus (EIAV).
Peripheral blood mononuclear cells (PBMC) were isolated, stained with CFSE and incubated with EIAV for 5 days. After interacted with either CD4(+) or CD8(+) antibody, the cells were detected for proliferated population, which contained serially 2-fold reduced CFSE in CD4(+) and CD8(+) T lymphocytes.
The concentration of CFSE, and the type, concentration and reaction time of EIAV-specific antigens were tested and optimized to improve the sensitivity and specificity of this flow cytometry-based assay. PBMCs isolated from the horses infected with either virulent or vaccine strains of EIAV and health controls were analyzed to evaluate this technique. The proliferation rates of CD4(+) and CD8(+) T lymphocytes were observed in the cells from differently treated horses.
The CFSE-based flow cytometry is a reliable tool to analyze antigen-specific proliferation of lymphocytes, which plays an important role in evaluating the immune responses induced by EIAV and other viruses.
Xi bao yu fen zi mian yi xue za zhi = Chinese journal of cellular and molecular immunology 12/2008; 24(11):1044-7.
