Insights into vaccine development for acquired immune deficiency syndrome from crystal structures of human immunodeficiency virus-1 gp41 and equine infectious anemia virus gp45

Magnetic Resonance Features of Acquired Immune Deficiency Syndrome Involving Central Nervous System Diseases by Intelligent Fuzzy C-Means Clustering (FCM) Algorithm

This study was aimed to explore the application of fuzzy C-means (FCM) algorithm in MR images of acquired immune deficiency syndrome (AIDS) patients. Sixty AIDS patients with central nervous disease were selected as the research object. A method of brain MR image segmentation based on FCM clustering optimization was proposed, and FCM was optimized based on the neighborhood pixel correlation of gray difference. The correlation was introduced into the objective function to obtain more accurate pixel membership and segmentation features of the image. The segmented image can retain the original image information. The proposed algorithm can clearly distinguish gray matter from white matter in images. The average time of image segmentation was 0.142 s, the longest time of level set algorithm was 2.887 s, and the running time of multithreshold algorithm was 1.708 s. FCM algorithm had the shortest running time, and the average time was significantly better than other algorithms (P < 0.05). FCM image segmentation efficiency was above 90%, and patients can clearly display the location of lesions after MRI imaging examination. In summary, FCM algorithm can effectively combine the spatial neighborhood information of the brain image, segment the BRAIN MR image, analyze the characteristics of AIDS patients from different directions, and provide effective treatment for patients.

SARS-CoV 2 spike protein S1 subunit as an ideal target for stable vaccines: A bioinformatic study

The Covid-19 a pandemic infectious disease and affected life across the world resulting in over 188.65 million confirmed cases across 223 countries, territories and areas with 4.06 million deaths. It is caused by a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and spike (S) protein of SARS-CoV-2, which plays a key role in the receptor recognition and cell membrane fusion process, is composed of two subunits, S1 and S2. The S1 subunit contains a receptor-binding domain (RBD) that recognizes and binds to the host receptor angiotensin-converting enzyme 2 (ACE2), while the S2 subunit mediates viral cell membrane fusion. Hence, it is a key target for developing neutralizing antibodies. Here, we have performed phylogenetic analysis and structural modeling of the SARS-CoV-2 spike glycoprotein, which is found highly conserved. The overall percent protein sequence identity from the SARS-CoV-2 spike protein sequences from the NCBI database was 99.68%. The functional domains of the S protein reveal that the S1 subunit was highly conserved (99.70%) than the S2 subunit (99.66%). Further, the 319-541 residues (RBD) of amino acids within the S1 domain were 100% similar among the spike protein. The 3D modeling of SARS-CoV-2 spike glycoprotein indicated that S protein has four domains with five protein units and the S1 subunit from 1 to 289 amino acid of domain 1 is highly conserved without any change in the ligand interaction site. This analysis clearly suggests that the S1 subunit (RBD 319-541) can be used as a target region for stable and safe vaccine development.

The Importance of Glycosylation in COVID-19 Infection

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is currently one of the major health problems worldwide. SARS-CoV-2 survival and virulence are shown to be impacted by glycans, covalently attached to proteins in a process of glycosylation, making glycans an area of interest in SARS-CoV-2 biology and COVID-19 infection. The SARS-CoV-2 uses its highly glycosylated spike (S) glycoproteins to bind to the cell surface receptor angiotensin-converting enzyme 2 (ACE2) glycoprotein and facilitate host cell entry. Viral glycosylation has wide-ranging roles in viral pathobiology, including mediating protein folding and stability, immune evasion, host receptor attachment, and cell entry. Modification of SARS-CoV-2 envelope membrane with glycans is important in host immune recognition and interaction between S and ACE2 glycoproteins. On the other hand, immunoglobulin G, a key molecule in immune response, shows a distinct glycosylation profile in COVID-19 infection and with increased disease severity. Hence, further studies on the role of glycosylation in SARS-CoV-2 infectivity and COVID-19 infection are needed for its successful prevention and treatment. This chapter focuses on recent findings on the importance of glycosylation in COVID-19 infection.

DNA adjuvant Amiloride conjunct long immunization interval promote higher antibody responses to HIV-1 gp41 and gp140 immunogens

Recent studies have revealed that the interface of gp120 and gp41 and some parts of gp41 are also critical epitopes for elicitation of broadly neutralizing antibodies. Therefore, potential trimeric gp41 or gp140 immunogen candidates are needed. Previously, we developed a trimer motif MTQ and demonstrated that it could help formation of trimeric gp120 and gp140 proteins. In the present study, we immunized Balb/c mice using trimeric gp41-expressing plasmid for prime and monomeric gp41 or trimeric gp140 protein as well as a mutant (Q577A) for boost. The antibody responses in the context of regimens with various immunization intervals and DNA adjuvants including praziquantel (PZQ), cimetidine (CIM), and amiloride (AML) were evaluated. We found that these three adjuvants were not enough to elicit remarkable specific Abs after gp41 DNA immunization, while AML could significantly promote humoral immune responses after protein boosts. Long immunization interval could induce the specific binding Abs earlier and higher and maintain a high level of Abs in the following 27 weeks after final protein boost. Moreover, two times of protein boosts with DNA adjuvant and a longer time interval achieved a higher titer of specific Abs than three times of protein boosts with a shorter time interval. Q577A mutant was benefit for trimeric gp140 boost in the production of binding Abs but harmful to inducing neutralizing Abs, while this mutant in monomeric gp41 presented the opposite trend which may be associated with the immunogen structures. This study highlights the significance of DNA adjuvant Amiloride and long immunization interval in promoting antibody responses and provides new insights into effective HIV immunization regimen design in the future.

The SARS-CoV-2 Spike Glycoprotein Biosynthesis, Structure, Function, and Antigenicity: Implications for the Design of Spike-Based Vaccine Immunogens

The ongoing pandemic of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), poses a grave threat to global public health and imposes a severe burden on the entire human society. Like other coronaviruses, the SARS-CoV-2 genome encodes spike (S) glycoproteins, which protrude from the surface of mature virions. The S glycoprotein plays essential roles in virus attachment, fusion and entry into the host cell. Surface location of the S glycoprotein renders it a direct target for host immune responses, making it the main target of neutralizing antibodies. In the light of its crucial roles in viral infection and adaptive immunity, the S protein is the focus of most vaccine strategies as well as therapeutic interventions. In this review, we highlight and describe the recent progress that has been made in the biosynthesis, structure, function, and antigenicity of the SARS-CoV-2 S glycoprotein, aiming to provide valuable insights into the design and development of the S protein-based vaccines as well as therapeutics.

A non-canonical binding interface in the crystal structure of HIV-1 gp120 core in complex with CD4

Numerous crystal structures of HIV gp120 have been reported, alone or with receptor CD4 and cognate antibodies; however, no sole gp120/CD4 complex without stabilization by an antibody is available. Here, we report a crystal structure of the gp120/CD4 complex without the aid of an antibody from HIV-1 CRF07_BC, a strain circulating in China. Interestingly, in addition to the canonical binding surface, a second interacting interface was identified. A mutagenesis study on critical residues revealed that the stability of this interface is important for the efficiency of Env-mediated membrane fusion. Furthermore, we found that a broad neutralizing antibody, ibalizumab, which targets CD4 in the absence of gp120, occupies the same binding surface as the second interface identified here on gp120. Therefore, we identified the possibility of the involvement of a second gp120-CD4 interaction interface during viral entry, and also provided a reasonable explanation for the broad activity of neutralizing antibody ibalizumab.

Structural and functional characterization of EIAV gp45 fusion peptide proximal region and asparagine-rich layer

Equine infectious anaemia virus (EIAV) and human immunodeficiency virus (HIV) are members of the lentiviral genus. Similar to HIV gp41, EIAV gp45 is a fusogenic protein that mediates fusion between the viral particle and the host cell membrane. The crystal structure of gp45 reported reveals a different conformation in the here that includes the fusion peptide proximal region (FPPR) and neighboring asparagine-rich layer compared with previous HIV-1 gp41 structures. A complicated hydrogen-bond network containing a cluster of solvent molecules appears to be critical for the stability of the gp45 helical bundle. Interestingly, viral replication was relatively unaffected by site-directed mutagenesis of EIAV, in striking contrast to that of HIV-1. Based on these observations, we speculate that EIAV is more adaptable to emergent mutations, which might be important for the evolution of EIAV as a quasi-species, and could potentially contribute to the success of the EIAV vaccine.