Biomedical subjects

Zuqiang Liu

Publications and source records attributed to Zuqiang Liu.

6 recordsLinked to original sources

PubMed2005

Predefined spacers between epitopes on a recombinant epitope-peptide impacted epitope-specific antibody response.

We have developed a widely applicable method to construct epitope-peptide gene for epitope-vaccine strategy recently. In this study, we wanted to know whether the predefined spacers between epitopes on a recombinant epitope-peptide impacted the production of epitope-specific antibodies. The neutralizing epitope ELDKWA on the C-domain of HIV-1 gp41 was defined by the monoclonal antibody (mAb) 2F5 with broad neutralizing activity. We constructed three recombinant ELDKWA-epitope-peptides with different spacers between epitopes. The recombinant epitope-peptide GST-K8, GST-S8 and GST-R8 were bearing eight copies of ELDKWA-epitope with amino acid spacer GS, GSGGGGS and RS, respectively. GST-K8 and GST-S8 could induce high titer of ELDKWA-epitope-specific antibodies, much better than GST-R8. Besides, both antibodies could recognize the recombinant soluble gp41 and the transfected CHO-WT cells that stably express HIV-1 envelope glycoprotein on the cell surfaces. These experimental results indicated that the spacer GSGGGGS and GS were feasible in constructing a recombinant epitope-vaccine.

Animals↗

PubMed2005

The recombinant immunogen with high-density epitopes of ELDKWA and ELDEWA induced antibodies recognizing both epitopes on HIV-1 gp41.

The high mutation rate of HIV-1 (human immunodeficiency virus-1) is a major obstacle to developing an effective vaccine. The mutation of ELDKWA-(aa669-674) to ELDEWA-epitope on HIV-1 gp41 caused the immune escape from neutralization by potent anti-HIV-1 human monoclonal antibody (mAb) 2F5. In this study, we suggested and evaluated a multi-epitope vaccine as a new strategy to develop HIV-1 vaccines. A glutathione S-transferase (GST) fusion protein (GST-K8E8) containing 8 copies of ELDKWA-and mutated ELDEWA-epitopes was constructed and used to immunize mice or rabbits. Analysis of the antisera (rAS3) induced by GST-K8E8 suggested that multi-epitope vaccine immunogen could raise antibodies in mice and rabbits against either the original ELDKWA-epitope or the mutated ELDEWA-epitope that resulted in immune escape. Briefly, ELDKWA-epitope-specific antibodies, directly purified from rAS3 by ELDKWA-epitope-peptide affinity chromatography, recognized either original gp41 protein (ELDKWA, rgp41K) or mutated gp41 (ELDEWA, rgp41E) in immunoblotting assay; in contrast, the existing ELDKWA-epitope antibodies recognized only rgp41K but not rgp41E, which were purified by ELDKWA-epitope-peptide affinity chromatography from rAS3 that were firstly completely pre-absorbed by ELDEWA-epitope-peptide affinity beads. And the same results were also observed when detecting the ELDEWA-epitope-specific antibodies in rAS3 by a means similar to the above. All the data presented here demonstrated that a high density multi-epitope vaccine could be an interesting strategy against HIV-1 mutation.

Animals↗

PubMed2004

High epitope density in a single recombinant protein molecule of the extracellular domain of influenza A virus M2 protein significantly enhances protective immunity.

The degree of epitope density has been shown to be a critical factor influencing the magnitude of epitope-specific responses. However, whether high epitope density in just a single protein molecule can still enhance the humoral response or, more importantly, the protective immunity, has not been determined. To test this, five glutathione-S-transferase fusion proteins bearing various numbers of copies of the M2e epitope on M2 protein of influenza virus (1, 2, 4, 8 and 16 copies) were prepared, and used to immunize mice and rabbits. Our data show clearly that M2e-specific humoral response was enhanced with increasing epitope density. By lethal challenge assay in mice, it was observed that recombinant proteins with higher M2e epitope densities resulted in higher survival rates and slower weight losses. The survival rate was directly related to the degree of epitope density in the single recombinant protein: 100% in the case of 16 M2e copies; 50% with 4 M2e epitopes; and 0% with one.

Animals↗

PubMed2004

Design and construction of a recombinant epitope-peptide gene as a universal epitope-vaccine strategy.

The multiple sequence and antigenic variability of HIV-1 has led to unprecedented difficulties in the development of effective vaccines. More and more experimental evidence suggests that HIV-1 mutants have resulted in immune evasion and pose a challenge for conventional efforts to prepare effective vaccines. We have suggested that an epitope-vaccine could offer a new strategy against HIV-1. Several candidate epitope-vaccines were prepared and systematically studied in animal experiments. Here, we have proposed a universal method for the preparation of immunogens for an epitope-vaccine by genetic engineering. With this method, copies of epitopes from one or more antigens can be conveniently combined into one recombinant immunogen, which may also help to design epitope-vaccines against other viral infections.

AIDS Vaccines↗

PubMed2003

Epitope-vaccine strategy against HIV-1: today and tomorrow.

Vaccines play important roles in preventing infectious diseases caused by different pathogens. However, some pathogens such as HIV-1 challenge current vaccine strategy. Poor immunogenicity and the high mutation rate of HIV-1 make great difficulties in inducing potent immune responses strong enough to prevent infection via vaccination. Epitope-vaccine, which could intensively enhance predefined epitope-specific immune responses, was suggested as a new strategy against HIV-1 and HIV-1 mutation. Epitope-vaccines afford powerful approaches to elicit potent, broad and complete immune protection against not only primary homologous viral isolates but also heterologous viral mutants. Although most studies are still preliminary now, epitope-vaccine as a novel strategy against the AIDS epidemic has great developmental potential. To trigger T-cell-dependent IgG antibody responses and improve affinities of the epitope-specific antibodies, approaches such as recombinant multi-epitope-vaccination and prime-boosting vaccination were suggested. Cellular immune responses, especially CTL responses, could also be elicited and enhanced in addition to humoral immune responses. Developed epitope-vaccines activating both arms of the immune system would benefit prevention and immunotherapy not only against HIV but also other chronic infections.

AIDS Vaccines↗

PubMed2002

A predefined epitope-specific monoclonal antibody recognizes ELDEWA-epitope just presenting on gp41 of HIV-1 O clade.

Diverse variation of HIV-1 is a grave challenge for prevention of viral infection and immunotherapy. Monoclonal antibody (mAb) 2F5 recognizing an epitope ELDKWA (aa669-674) on HIV-1 envelope protein gp41 showed broad neutralizing activity against a lot of HIV-1 strains including primary isolates. However, viral mutation from ELDKWA to ELDEWA resulted in viral evasion from neutralization by mAb 2F5. Using ELDEWA-epitope-peptide (C-GFLDEWAGELDEWA) conjugated with carrier protein keyhole limpet hemocyanin (KLH), a mAb 14D9 (IgGl) was prepared and identified as the mAb with predefined ELDEWA-epitope specificity. The mAb 14D9 recognized the ELDEWA epitope, but not other three epitopes (ELDKWA, ELNKWA and ELEKWA). In comparison, mAb 2F5 could recognize only ELDKWA, but not three neutralization-resistant epitopes (ELDEWA, ELNKWA and ELEKWA). Interestingly, we searched several authoritative HIV sequence databases (http://hiv-web.lanl.gov) and found out that nearly all the viral isolates bearing the ELDEWA epitope belong to the O clade, the only exceptional viral isolate bearing the epitope ELDEWA has been demonstrated to be an intergroup M/O recombinant, which suggests that the ELDEWA-epitope on gp41 represents a specific epitope-marker of HIV-1 O clade. To confirm whether the mAb 14D9 recognizes gp41 of HIV-1 O clade, the rsgp41(IIIB), bearing ELDKWA-epitope was site-directed-mutated to the rsgp41 bearing ELDEWA-epitope. The mAb 14D9 could bind to rsgp41 bearing ELDEWA-epitope in immunoblotting analysis, did not bind to rsgp41 bearing ELDKWA-epitope. These experimental results suggest that the mAb 14D9 with predefined ELDEWA-epitope specificity may be applied to HIV-1 O clade identification.

AIDS Vaccines↗