The possible role of CCR5Δ32 mutation in Crimean-Congo hemorrhagic fever infection

Novel small synthetic HIV-1 V3 crown variants: CCR5 targeting ligands

The CC chemokine receptor 5 (CCR5) antagonism represents a promising pharmacological strategy for therapeutic intervention as it plays a significant role in reducing the severity and progression of a wide range of pathological conditions. Here we designed and generated peptide ligands targeting the chemokine receptor, CCR5, that were derived from the critical interaction sites of the V3 crown domain of envelope protein glycoprotein gp120 (TRKSIHIGPGRAFYTTGEI) of HIV-1 using computational biology approach and the peptide sequence corresponding to this region was taken as the template peptide, designated as TMP-1. The peptide variants were synthesized by employing Fmoc chemistry using polymer support and were labelled with rhodamine B to study their interaction with the CCR5 receptor expressed on various cells. TMP-1 and TMP-2 were selected as the high-affinity ligands from in vitro receptor-binding assays. Specific receptor-binding experiments in activated peripheral blood mononuclear cells and HOS.CCR5 cells indicated that TMP-1 and TMP-2 had significant CCR5 specificity. Further, the functional analysis of TMP peptides using chemotactic migration assay showed that both peptides did not mediate the migration of responsive cells. Thus, template TMP-1 and TMP-2 represent promising CCR5 targeting peptide candidates.

Methylene-tetrahydrofolate reductase gene C677T and A1298C polymorphisms as a risk factor for Crimean-Congo hemorrhagic fever

Crimean-Congo hemorrhagic fever (CCHF) is a deadly viral disease. Methylene-tetrahydrofolate reductase (MTHFR) has an important role in folate metabolism, and also in the formation of new cells, DNA synthesis, repair and methylation. We aimed to examine the relationship between MTHFR gene C677T (Ala222Val, rs1801133) and A1298C (Glu429Ala, rs1801131) polymorphisms with CCHF in a Turkish population. Totally 273 participants were included in the current study. One hundred forty-one participants were CCHF patients and one hundred thirty-two participants were healthy controls. The polymerase chain reaction (PCR) and further restriction fragment length polymorphism (RFLP) assays were applied to determine the genotypes of MTHFR polymorphisms. We did not find any differences between the CCHF patients and healthy controls in terms of allele and genotype distributions of both the C677T and A1298C polymorphisms. In composite genotype analysis between different groups, the frequency of CT-AA composite genotype, which is formed by C677T-A1298C polymorphisms, was found to be significantly higher in Mild CCHF patients compared to both Severe CCHF patients and controls (p = 0.036 and p = 0.008, respectively). In conclusion, in this study, we found a relationship between CCHF and MTHFR gene polymorphisms. CT-AA composite genotype of MTHFR gene C677T and A1298C polymorphisms showed a predisposition to Mild CCHF.

Beyond HIV infection: Neglected and varied impacts of CCR5 and CCR5Δ32 on viral diseases

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CCR5 regulates multiple cell types (e.g., T regulatory and Natural Killer cells) and immune responses.

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The effects of CCR5, CCR5Δ32 (variant associated with reduced CCR5 expression) and CCR5 antagonists vary between infections.

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CCR5 affects the pathogenesis of flaviviruses, especially in the brain.

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The genetic variant CCR5Δ32 increases the risk of symptomatic West Nile virus infection.

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The triad “CCR5, extracellular vesicles and infections” is an emerging topic.

The interactions between chemokine receptors and their ligands may affect susceptibility to infectious diseases as well as their clinical manifestations. These interactions mediate both the traffic of inflammatory cells and virus-associated immune responses. In the context of viral infections, the human C-C chemokine receptor type 5 (CCR5) receives great attention from the scientific community due to its role as an HIV-1 co-receptor. The genetic variant CCR5Δ32 (32 base-pair deletion in CCR5 gene) impairs CCR5 expression on the cell surface and is associated with protection against HIV infection in homozygous individuals. Also, the genetic variant CCR5Δ32 modifies the CCR5-mediated inflammatory responses in various conditions, such as inflammatory and infectious diseases. CCR5 antagonists mimic, at least in part, the natural effects of the CCR5Δ32 in humans, which explains the growing interest in the potential benefits of using CCR5 modulators for the treatment of different diseases. Nevertheless, beyond HIV infection, understanding the effects of the CCR5Δ32 variant in multiple viral infections is essential to shed light on the potential effects of the CCR5 modulators from a broader perspective. In this context, this review discusses the involvement of CCR5 and the effects of the CCR5Δ32 in human infections caused by the following pathogens: West Nile virus, Influenza virus, Human papillomavirus, Hepatitis B virus, Hepatitis C virus, Poliovirus, Dengue virus, Human cytomegalovirus, Crimean-Congo hemorrhagic fever virus, Enterovirus, Japanese encephalitis virus, and Hantavirus. Subsequently, this review addresses the impacts of CCR5 gene editing and CCR5 modulation on health and viral diseases. Also, this article connects recent findings regarding extracellular vesicles (e.g., exosomes), viruses, and CCR5. Neglected and emerging topics in “CCR5 research” are briefly described, with focus on Rocio virus, Zika virus, Epstein-Barr virus, and Rhinovirus. Finally, the potential influence of CCR5 on the immune responses to coronaviruses is discussed.

Role of the genetic variant CCR5Δ32 in HBV infection and HBV/HIV co-infection

CCR5 is a chemokine receptor that mediates the action of inflammatory cells, besides acting as an HIV co-receptor. CCR5Δ32 states for a genetic variant containing a 32 base pair deletion in the coding region of the CCR5 gene. In homozygosis, CCR5Δ32 results in the lack of CCR5 expression on the cell surface, which was associated with protection against HIV infection. Heterozygous individuals for CCR5Δ32 have a reduced CCR5 expression. Recent evidence demonstrates that CCR5 and CCR5Δ32 are involved in the pathogenesis of other viral infections besides HIV infection. Nevertheless, the role of CCR5 and CCR5Δ32 in HBV infection is not clear and conflicting results have been reported. Thus, the objective of this study was to investigate the role of CCR5Δ32 in HBV mono-infection and HBV/HIV co-infection in a population from southern Brazil. A total of 1113 individuals were evaluated, divided in controls (n = 334), HBV+ (n = 335), HBV+/HIV+ (n = 144), and including an HIV+ group to complement the analyses (n = 300, obtained from a previous study of our research team). The CCR5Δ32 allele frequencies found were 7.5 %, 9.0 %, and 3.1 %, respectively for controls, HBV+, and HBV+/HIV+ patients. The individuals were classified in CCR5Δ32 allele carriers and CCR5Δ32 allele non-carriers and the groups were compared using binary logistic regression adjusted for covariates. No significant effect of the CCR5Δ32 variant was observed on the susceptibility or protection against HBV mono-infection in individuals from southern Brazil. A potential protective effect of CCR5Δ32 on HBV/HIV co-infection was observed. However, it can be due to the effect of CCR5Δ32 in the protection against HIV infection or external factors not covered in the study. Finally, this study contributes to the understanding of the role of CCR5 in HBV infection, suggesting no effect of CCR5Δ32 on susceptibility to HBV mono-infection.

Predominance of the heterozygous CCR5 delta-24 deletion in African individuals resistant to HIV infection might be related to a defect in CCR5 addressing at the cell surface

INTRODUCTION

The chemokine receptor CCR5 is the main co-receptor for R5-tropic HIV-1 variants. We have previously described a novel 24-base pair deletion in the coding region of CCR5 among individuals from Rwanda. Here, we investigated the prevalence of hCCR5Δ24 in different cohorts and its impact on CCR5 expression and HIV-1 infection in vitro.

METHODS

We screened hCCR5Δ24 in a total of 3232 individuals which were either HIV-1 uninfected, high-risk HIV-1 seronegative and seropositive partners from serodiscordant couples, Long-Term Survivors, or HIV-1 infected volunteers from Africa (Rwanda, Kenya, Guinea-Conakry) and Luxembourg, using a real-time PCR assay. The role of the 24-base pair deletion on CCR5 expression and HIV infection was assessed in cell lines and PBMC using mRNA quantification, confocal analysis, flow and imaging cytometry.

RESULTS AND DISCUSSION

Among the 1661 patients from Rwanda, 12 individuals were heterozygous for hCCR5Δ24 but none were homozygous. Although heterozygosity for this allele may not confer complete resistance to HIV-1 infection, the prevalence of the mutation was 2.41% (95%CI: 0.43; 8.37) in 83 Long-Term Survivors (LTS) and 0.99% (95%CI: 0.45; 2.14) in 613 HIV-1 exposed seronegative members as compared with 0.35% (95% Cl: 0.06; 1.25) in 579 HIV-1 seropositive members. The prevalence of hCCR5Δ24 was 0.55% (95%CI: 0.15; 1.69) in 547 infants from Kenya but the mutation was not detected in 224 infants from Guinea-Conakry nor in 800 Caucasian individuals from Luxembourg. Expression of hCCR5Δ24 in cell lines and PBMC showed that the hCCR5Δ24 protein is stably expressed but is not transported to the plasma membrane due to a conformational change. Instead, the mutant receptor was retained intracellularly, colocalized with an endoplasmic reticulum marker and did not mediate HIV-1 infection. Co-transfection of hCCR5Δ24 and wtCCR5 did not indicate a transdominant negative effect of CCR5Δ24 on wtCCR5.

CONCLUSIONS

Our findings indicate that hCCR5Δ24 is not expressed at the cell surface. This could explain the higher prevalence of the heterozygous hCCR5Δ24 in LTS and HIV-1 exposed seronegative members from serodiscordant couples. Our data suggest an East-African localization of this deletion, which needs to be confirmed in larger cohorts from African and non-African countries.

Host immunogenetics in tick-borne encephalitis virus infection-The CCR5 crossroad

The human Tick-borne encephalitis virus (TBEV) infection is a complex event encompassing factors derived from the virus itself, the vectors, the final host, and the environment as well. Classically, genetic traits stand out among the human factors that modify the susceptibility and progression of infectious diseases. However, and although this is a changing scenario, studies evaluating the genetic factors that affect the susceptibility specifically to TBEV infection and TBEV-related diseases are still scarce. There are already some interesting pieces of evidence showing that some genes and polymorphisms have a real impact on TBEV infection. Also, the inflammatory processes involving tick-human interactions began to be understood in greater detail. This review focuses on the immunogenetic and inflammatory aspects concerning tick-host interactions, TBEV infections, and tick-borne encephalitis. Of note, it has been described that polymorphisms in CD209, GSTM1, IL-10, IL-28B, MMP9, OAS2, OAS3, and TLR3 have a statistically significant impact on TBEV infection. Besides, CCR5, its ligands, and the CCR5Δ32 genetic variant seem to have a very important influence on the infection and its immune responses. Taking this information into consideration, a special discussion regarding the effects of CCR5 on TBEV infection and tick-borne encephalitis will be presented. Emerging topics (such as exosomes, evasins, and CCR5 blockers) involving immunological and inflammatory aspects of TBEV-human interactions will also be addressed. Lastly, the current picture of TBEV infection and the importance to address the TBEV-associated problems through the One Health perspective will be discussed.

Effects of Paraoxonase-1 variants on course of severity and mortality of Crimean-Congo hemorrhagic fever

Crimean-Congo hemorrhagic fever (CCHF) is an acute viral hemorrhagic fever caused by Crimean Congo hemorrhagic fever virus (CCHFV). Paraoxonase-1 (PON1) is a high density lipoprotein (HDL)-binding protein which defense the body against oxidative stress. To investigate the role of the PON1 gene in CCHF, we screened the genotypes of two single nucleotide polymorphisms (Q192R [rs662] and L55M [rs854560]) in CCHF patients stratified according to course of severity and mortality by using PCR-based RFLP assay. Overall, 132 patients diagnosed as CCHF were enrolled in this study. The frequencies of the three genotypes and two alleles of Q192R and L55M polymorphisms didn't show any statistically significant differences in terms of mortality and disease severity (p > 0.05). Any statistically significant differences were not found between severe and mild and fatal and non-fatal CCHF patients according to seven composite genotypes (p > 0.05). When we analyzed the clinical characteristics of CCHF patients stratified according to PON1gene polymorphisms, any statistically significant differences were not also observed (p > 0.05). Our study showed no possible association between genotypes of PON1 gene Q192R and L55M polymorphisms and CCHF.

The Expanding Therapeutic Perspective of CCR5 Blockade

CCR5 and its interaction with chemokine ligands have been crucial for understanding and tackling HIV-1 entry into target cells. However, over time, CCR5 has witnessed an impressive transition from being considered rather unimportant in physiology and pathology to becoming central in a growing number of pathophysiological conditions. It now turns out that the massive efforts devoted to combat HIV-1 entry by interfering with CCR5, and the subsequent production of chemokine ligand variants, small chemical compounds, and other molecular entities and strategies, may set the therapeutic standards for a wealth of different pathologies. Expressed on various cell types, CCR5 plays a vital role in the inflammatory response by directing cells to sites of inflammation. Aside HIV-1, CCR5 has been implicated in other infectious diseases and non-infectious diseases such as cancer, atherosclerosis, and inflammatory bowel disease. Individuals carrying the CCR5Δ32 mutation live a normal life and are warranted a natural barrier to HIV-1 infection. Therefore, CCR5 antagonism and gene-edited knockout of the receptor gained growing interest for the therapeutic role that CCR5 blockade may play in the attenuation of the severity or progression of numerous diseases.