Immunogenicities of Env glycoproteins from circulating HIV-1 isolates in China focusing on the strategy of "DNA prime plus protein boost".
ABSTRACT The adenovirus-based HIV-1 vaccine developed by Merck Company suffered from an unexpected failure in September 2007. This generated a big shift in the strategy of HIV vaccine development with renewed focus on the induction of neutralizing antibodies. A major challenge in developing an HIV-1 vaccine is to identify immunogens and adopt delivery methods that can elicit broadly neutralizing antibodies against primary isolates of different genetic subtypes.
Most circulating HIV-1 isolates in China are composed of clades Thai-B, CRF_BC and CRF01_AE. In order to construct DNA vaccines against these 3 HIV-1 subtypes, DNA vaccines carrying the gp120 regions from HIV-1 isolates of GX48(AE), GX79(AE), NX22(BC), GS22(BC), HN24(Thai-B) were constructed. Expression of gp120 from these DNA vaccines was detected by Western blotting in transiently transfected 293T cells. Pilot immunizations of New Zealand white rabbits were performed using the strategy of "DNA prime plus protein boost" and the neutralizing antibody response was detected in a Tzm-bl cell based assay against different HIV-1 strains.
Response of gp120-specific antibody was relatively low after DNA primes (mean titer = 10(4.72)); however, the titer of gp120-specific antibody went up with 2 protein boosts (mean titer = 10(6.81)). Above all, neutralizing antibody (Nab) titers induced by this combined approach were much better than those elicited by DNA or protein used alone (P < 0.01). Neutralizing activities of immunized rabbit sera against several pseudoviruses and laboratorial strains were evaluated, most rabbit sera primed with monovalent vaccine were capable of neutralizing only 1 of 5 viruses, however, sera primed with the polyvalent DNA vaccines were able to neutralize at least 2 of 5 viruses.
Polyvalent DNA prime plus protein boost is an effective immunization strategy to broaden the neutralization breadth and further research should be performed on the basis of this pilot study.
- SourceAvailable from: Shan Lu
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- "A DNA vaccine (HN24) expressing CNHN24 gp120 was constructed and its expression by this DNA vaccine vector was confirmed by Western blot using supernatant that was transiently expressed in 293T cells (Fig 5-A). Rabbits were immunized with either a DNA prime-protein boost approach or protein immunization alone after receiving the mock immunization of empty DNA vector without HIV-1 Env antigen, as reported (Wang et al., 2009). Animal studies were conducted with the review and approval by the University of Massachusetts Medical School (UMMS) Institutional Animal Care and Use Committee (IACUC) according to accepted international animal welfare regulations. "
ABSTRACT: A novel HIV-1 Env expression vector (SF162-Z) was developed by introducing two new cloning sites on the backbone of an existing vector that produces a full length Env from HIV-1 SF162 isolate. These sites facilitate the swapping of the gp120 portion of the SF162 Env with matching gp120 antigens from HIV-1 isolates of different genetic clades. Final production of functional pseudotyped viruses will express chimeric Env antigens, including gp41 of the parental SF162 and gp120 from other primary isolates. This system is useful for testing the neutralizing sensitivity of partial env gene products frequently identified in viral quasi species in patients infected with HIV or when only partial gp120 gene products are available.Journal of virological methods 10/2010; 171(1):183-9. DOI:10.1016/j.jviromet.2010.10.022 · 1.88 Impact Factor
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ABSTRACT: Hand, foot, and mouth disease (HFMD) is a common viral illness in young children. HFMD is caused by viruses belonging to the enterovirus genus of the picornavirus family. Recently, enterovirus 71 (EV71) has emerged as a virulent agent for HFMD with severe clinical outcomes. In the current report, we conducted a pilot antigen engineering study to optimize the expression and immunogenicity of subunit VP1 antigen for the design of EV71 vaccines. DNA immunization was adopted as a simple technical approach to test different designs of VP1 antigens without the need to express VP1 protein in vitro first. Our studies indicated that the expression and immunogenicity of VP1 protein can be improved with alternated VP1 antigen designs. Data presented in the current report revealed novel pathways to optimize the design of VP1 antigen-based EV71 vaccines.Biochemical and Biophysical Research Communications 03/2012; 420(4):755-61. DOI:10.1016/j.bbrc.2012.03.067 · 2.28 Impact Factor
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ABSTRACT: INTRODUCTION: The development of an effective vaccine against HIV-1 has been challenging but recent advances in both the HIV prevention landscape and the partial efficacy of the recent RV144 vaccine efficacy trial in Thailand provide hope for an improved arsenal of approaches to prevent HIV-1 transmission. AREAS COVERED: This review describes recent advances in HIV-1 prevention such as circumcision, microbicides and pre-exposure prophylaxis with antiretroviral therapy, but focuses mainly on the current state of HIV-1 vaccine development in the post-RV144 era. EXPERT OPINION: The field of HIV-1 vaccine development has been plagued by the unprecedented challenges involved with designing a vaccine effective in preventing transmission of a retrovirus, due in part to sequence diversity, retroviral integration into host chromosomes, establishment of reservoir sites and glycosylation shielding of the HIV-1 envelope. The partial efficacy of the recent RV144 vaccine trial in Thailand may allow for better understanding of immune correlates of infection risk, which could enable iterative improvements to vaccine regimens in the development pipeline. In parallel, a number of promising vaccine strategies incorporating viral vectors, novel immunogens, delivery systems and adjuvants are advancing in clinical development. Vaccine development must occur in parallel with continued advances in HIV-1 prevention.Expert opinion on biological therapy 05/2012; 12(8):983-94. DOI:10.1517/14712598.2012.688020 · 3.65 Impact Factor