Determination of HIV type 1 CRF01_AE gag p17 and env-V3 consensus sequences for HIV/AIDS vaccine design

Hepatitis C virus antigenic convergence

Vaccine development against hepatitis C virus (HCV) is hindered by poor understanding of factors defining cross-immunoreactivity among heterogeneous epitopes. Using synthetic peptides and mouse immunization as a model, we conducted a quantitative analysis of cross-immunoreactivity among variants of the HCV hypervariable region 1 (HVR1). Analysis of 26,883 immunological reactions among pairs of peptides showed that the distribution of cross-immunoreactivity among HVR1 variants was skewed, with antibodies against a few variants reacting with all tested peptides. The HVR1 cross-immunoreactivity was accurately modeled based on amino acid sequence alone. The tested peptides were mapped in the HVR1 sequence space, which was visualized as a network of 11,319 sequences. The HVR1 variants with a greater network centrality showed a broader cross-immunoreactivity. The entire sequence space is explored by each HCV genotype and subtype. These findings indicate that HVR1 antigenic diversity is extensively convergent and effectively limited, suggesting significant implications for vaccine development.

A computationally optimized broadly reactive antigen (COBRA) based H5N1 VLP vaccine elicits broadly reactive antibodies in mice and ferrets

Pandemic outbreaks of influenza are caused by the emergence of a pathogenic and transmissible virus to which the human population is immunologically naïve. Recent outbreaks of highly pathogenic avian influenza (HPAI) of the H5N1 subtype are of particular concern because of the high mortality rate (60% case fatality rate) and novel subtype. In order to develop a vaccine that elicits broadly reactive antibody responses against emerging H5N1 isolates, we utilized a novel antigen design technique termed computationally optimized broadly reactive antigen (COBRA). The COBRA HA sequence was based upon HA amino acid sequences from clade 2 H5N1 human infections and the expressed protein retained the ability to bind the receptor, as well as mediate particle fusion. Non-infectious recombinant VLP vaccines using the COBRA HA were purified from a mammalian expression system. Mice and ferrets vaccinated with COBRA HA H5N1 VLPs had protective levels of HAI antibodies to a representative isolates from each subclade of clade 2. Furthermore, VLP vaccinated animals were completely protected from a lethal challenge of the clade 2.2 H5N1 virus A/Whooper Swan/Mongolia/244/2005. This is the first report describing the use of COBRA-based antigen design. The COBRA HA H5N1 VLP vaccine elicited broadly reactive antibodies and is an effective influenza vaccine against HPAI virus.

Viral sequence diversity: challenges for AIDS vaccine designs

Among the greatest challenges facing AIDS vaccine development is the intrinsic diversity among circulating populations of HIV-1 in various geographical locations and the need to develop vaccines that can elicit enduring protective immunity to variant HIV-1 strains. While variation is observed in all of the viral proteins, the greatest diversity is localized to the viral envelope glycoproteins, evidently reflecting the predominant role of these proteins in eliciting host immune recognition and responses that result in progressive evolution of the envelope proteins during persistent infection. Interestingly, while envelope glycoprotein variation is widely assumed to be a major obstacle to AIDS vaccine development, there is very little experimental data in animal or human lentivirus systems addressing this critical issue. In this review, the state of vaccine development to address envelope diversity will be presented, focusing on the use of centralized and polyvalent sequence design as mechanisms to elicit broadly reactive immune responses.

A single-nucleotide synonymous mutation in the gag gene controlling human immunodeficiency virus type 1 virion production

Viral factors as well as host ones play major roles in the disease progression of human immunodeficiency virus type 1 (HIV-1) infection. We have examined cytotoxic T-lymphocyte activity and HIV-1 DNA PCR results of 312 high-risk seronegative drug users in northern Thailand and identified four seronegative cases positive for both assays. Furthermore, we have identified a synonymous mutation in nucleotide position 75 of the gag p17 gene (A426G) of HIV-1 that belongs to the CRF01_AE virus circulating in Thailand. The replication-competent HIV-1 clone containing the A426G mutation demonstrated a dramatic reduction of virion production and perturbation of viral morphogenesis without affecting viral protein synthesis in cells.