Diversification of specificity after maturation of the antibody response to the HIV gp41 epitope ELDKWA

The degree of HIV-1 amino acid variability is strictly related to different disease progression rates

The aim of this study is to evaluate the amino acid variability of HIV-1 Gp41, C2-V3, and Nef in a group of patients characterized by different disease progression rates. HIV-1 sequences were collected from 19 Long term non progressor patients (LTNPs), 9 slow progressors (SPs), and 11 rapid progressors (RPs). Phylogenetic trees were estimated by MEGA 6. Differences in amino acid variability among sequences belonging to the 3 groups have been evaluated by amino acid divergence, Shannon entropy analysis, and the number of amino acid mutations (defined as amino acid variations compared with HxB2). The involvement of amino acid mutations on epitope rich regions was also investigated. The population was mainly composed of males (74.3%) and HIV-1 subtype B strains (B: 92.32%, CRF_12BF, A1, C: 2.56% each). Viral load (log₁₀ copies/mL) and CD4⁺T cell count (cells/mm³) were 3.9 (3.5-4.2) and 618 (504-857) in LTNPs, 3.3 (2.8-4.7) and 463 (333-627) in SPs, and 4.6 (4.3-5.3) and 201 (110-254) in RPs. Gp41 and C2-V3 amino acid divergence was lower in LTNP and SP strains compared to RPs (median value: 0.085 and 0.091 vs. 0.114, p = 0.005 and 0.042) and a trend of lower variability was observed for Nef (p = 0.198). A lower entropy value was observed at 10, 3, and 7 positions of Gp41, C2-V3, and Nef belonging to LTNPs and at 7, 3, and 1 positions of Gp41, C2-V3, and Nef belonging to SPs compared with RPs (p < 0.05). Focusing on epitope rich regions, again a higher degree of conservation was observed in Gp41 and C2-V3 sequences belonging to LTNPs and SPs compared to those belonging to RPs. This study shows that the extent of amino acid variability correlates with a different HIV-1 progression rate. This variability also involves CTL epitope rich regions, thus suggesting its involvement in the immune escape process modulation.

An Env-derived multi-epitope HIV chimeric protein produced in the moss Physcomitrella patens is immunogenic in mice

The first report on the recombinant production of a candidate vaccine in the moss system. The need for economical and efficient platforms for vaccine production demands the exploration of emerging host organisms. In this study, the production of an antigenic protein is reported employing the moss Physcomitrella patens as an expression host. A multi-epitope protein from the Human Immunodeficiency Virus (HIV) based on epitopes from gp120 and gp41 was designed as a candidate subunit vaccine and named poly-HIV. Transgenic moss plants were generated carrying the corresponding poly-HIV transgene under a novel moss promoter and subsequently seven positive lines were confirmed by PCR. The poly-HIV protein accumulated up to 3.7 µg g(-1) fresh weight in protonema cultures. Antigenic and immunogenic properties of the moss-produced recombinant poly-HIV are evidenced by Western blots and by mice immunization assays. The elicitation of specific antibodies in mice was observed, reflecting the immunogenic potential of this moss-derived HIV antigen. This is the first report on the production of a potential vaccine in the moss system and opens the avenue for glycoengineering approaches for the production of HIV human-like glycosylated antigens as well as other vaccine prototypes under GMP conditions in moss bioreactors.