HIV-1 infection is characterized by generalized deregulation of the immune system, resulting in increased chronic immune activation. However, some individuals called HIV controllers (HICs) present spontaneous control of viral replication and have a more preserved immune system. Among HICs, discordant results have been observed regarding immune activation and the frequency of different T cell subsets, including Treg and Th17 cells. We evaluated T cell immune activation, differentiation and regulatory profiles in two groups of HICs—elite controllers (ECs) and viremic controllers (VCs)—and compared them to those of cART-treated individuals (cART) and HIV-1-negative (HIV-neg) individuals. ECs demonstrated similar levels of activated CD4⁺ and CD8⁺ T cells in comparison to HIV-neg, while cART and VCs showed elevated T cell activation. CD4⁺ T cell subset analyses showed differences only for transitional memory T cell frequency between the EC and HIV-neg groups. However, VC individuals showed higher frequencies of terminally differentiated, naïve, and stem cell memory T cells and lower frequencies of transitional memory and central memory T cells compared to the HIV-neg group. Among CD8⁺ T cell subsets, ECs presented higher frequencies of stem cell memory T cells, while VCs presented higher frequencies of terminally differentiated T cells compared to the HIV-neg group. HICs showed lower frequencies of total Treg cells compared to the HIV-neg and cART groups. ECs also presented higher frequencies of activated and a lower frequency of resting Treg cells than the HIV-neg and cART groups. Furthermore, we observed a high frequency of Th17 cells in ECs and high Th17/Treg ratios in both HIC groups. Our data showed that ECs had low levels of activated T cells and a high frequency of activated Treg and Th17 cells, which could restrict chronic immune activation and be indicative of a preserved mucosal response in these individuals.

HIV-1 has an antisense gene overlapping env that encodes the ASP protein. ASP functions are still unknown, but it has been associated with gp120 in the viral envelope and membrane of infected cells, making it a potential target for immune response. Despite this, immune response patterns against ASP are poorly described and can be influenced by the high genetic variability of the env gene. To explore this, we analyzed 100k HIV-1 ASP sequences from the Los Alamos HIV sequence database using phylogenetic, Shannon entropy (Hs), and logo tools to study ASP variability in worldwide and Brazilian sequences from the most prevalent HIV-1 subtypes in Brazil (B, C, and F1). Data obtained in silico guided the design and synthesis of 15-mer overlapping peptides through spot synthesis on cellulose membranes. Peptide arrays were screened to assess IgG and IgM responses in pooled plasma samples from HIV controllers and individuals with acute or recent HIV infection. Excluding regions with low alignment accuracy, several sites with higher variability (Hs > 1.5) were identified among the datasets (25 for worldwide sequences, 20 for Brazilian sequences). Among sites with Hs < 1.5, sequence logos allowed the identification of 23 other sites with subtype-specific signatures. Altogether, amino acid variations with frequencies > 20% in the 48 variable sites identified were included in 92 peptides, divided into 15 sets, representing near full-length ASP. During the immune screening, the strongest responses were observed in three sets, one in the middle and one at the C-terminus of the protein. While some sets presented variations potentially associated with epitope displacement between IgG and IgM targets and subtype-specific signatures appeared to impact the level of response for some peptides, signals of cross-reactivity were observed for some sets despite the presence of B/C/F1 signatures. Our data provides a map of ASP regions preferentially targeted by IgG and IgM responses. Despite B/C/F1 subtype signatures in ASP, the amino acid variation in some areas preferentially targeted by IgM and IgG did not negatively impact the response against regions with higher immunogenicity.

The yellow fever (YF) vaccine is one of the safest and most effective vaccines currently available. Still, its administration in people living with HIV (PLWH) is limited due to safety concerns and a lack of consensus regarding decreased immunogenicity and long-lasting protection for this population. The mechanisms associated with impaired YF vaccine immunogenicity in PLWH are not fully understood, but the general immune deregulation during HIV infection may play an important role. To assess if HIV infection impacts YF vaccine immunogenicity and if markers of immune deregulation could predict lower immunogenicity, we evaluated the association of YF neutralization antibody (NAb) titers with the pre-vaccination frequency of activated and exhausted T cells, levels of pro-inflammatory cytokines, and frequency of T cells, B cells, and monocyte subsets in PLWH and HIV-negative controls. We observed impaired YF vaccine immunogenicity in PLWH with lower titers of YF-NAbs 30 days after vaccination, mainly in individuals with CD4 count <350 cells/mm³. At the baseline, those individuals were characterized by having a higher frequency of activated and exhausted T cells and tissue-like memory B cells. Elevated levels of those markers were also observed in individuals with CD4 count between 500 and 350 cells/mm³. We observed a negative correlation between the pre-vaccination level of CD8⁺ T cell exhaustion and CD4⁺ T cell activation with YF-NAb titers at D365 and the pre-vaccination level of IP-10 with YF-NAb titers at D30 and D365. Our results emphasize the impact of immune activation, exhaustion, and inflammation in YF vaccine immunogenicity in PLWH.

Background: HIV controllers (HICs) constitute a heterogeneous group of HIV-1 individuals able to suppress plasma viremia to low or undetectable levels in the absence of antiretroviral therapy. Host genetic factors may be involved in the sustained control of viral replication observed. We investigated the distribution and the potential impact of human leukocyte antigens (HLA)-B and -C alleles, killer immunoglobulin-like receptor (KIR) genes, single nucleotide polymorphisms (SNPs) of the NLRP3, CARD8 and IL-1β inflammasome genes, and CCR5Δ32 mutation on the viral control among HICs. Methods: In total, 28 HICs were categorized as persistent elite controllers (PECs, n = 7), ebbing elite controllers (EECs, n = 7), and viremic controllers (VCs, n = 14) according to the level of natural suppression of viremia. HLA alleles were assigned by sequencing-based typing, KIR alleles by polymerase chain reaction (PCR) sequence-specific amplification, SNPs by real-time PCR, and the CCR5Δ32 mutation by PCR. Results: Significant differences were observed in the pairwise comparisons of protective HLA-B alleles, KIR Bx genotype, KIR2DL3 + C1 pair, KIR2DL5, and KIR2DS5 allelic carrier frequencies among the HIC groups. Multivariate models showed that HICs without the KIR2DL3 allele or without KIR2DL3 + C1/C2 pair, with the HLA-C*08 allele or with the NLRP3 rs10754558-G SNP had a higher mean hazard of a viral load above 2,000 copies/mL, while a lower mean hazard of this event was observed for HICs with KIR2DL5, KIR2DS1, KIR2DS5, and KIR3DS1 alleles. Moreover, HICs with the KIR2DS5 allele had less risk of undergoing viral load (VL) blips within the same normalized period than those participants without this allele, while HICs without the KIR2DL3 allele had a mean higher risk of experiencing VL blips. Conclusions: These results indicate that innate immune mechanisms may play an essential role in modulating the sustained control of viral replication in HICs.

This study aimed to identify the distinct intrinsic response potential of γδ T cells from COVID-19 patients with different illness severities, to better understand the implication of these cells in COVID-19 disease. Forty-four COVID patients were enrolled at hospitalization and classified as: moderate without oxygen support (MWO₂; N = 15), moderate with oxygen support (MO₂; N = 15), or severe disease requiring mechanical ventilation (SD; N = 14). γδ T cells were characterized ex vivo, isolated from peripheral blood cells, stimulated in vitro with OKT3 and K562 cells, and evaluated for functional markers by flow cytometry. Ex vivo analysis identified 16.21% of total γδ T cells as Vδ1⁻Vδ2⁻. SD patients presented a lower frequency of TRAIL⁺ and of IL-17-producing Vδ2 cells, as well as lower value of fluorescence intensity values for TNF-α in Vδ2 cells, than MWO₂ patients (p < 0.05). In addition, paired analyses showed a lower frequency of IL-17-producing than CD161⁺ Vδ2 cells in SD patients (p < 0.05). These observations suggest a more restricted response potential of the Vδ2 subset in severe disease, show the impact of general immune dysregulation on these cells, or even suggest some role for IL-17-producing Vδ2 cells in preventing critical symptoms.