HLA Alleles and Dengue Virus Infection in Venezuelan Patients: A Preliminary Study

HLA alleles and dengue susceptibility across populations in the era of climate change: a comprehensive review

Dengue, a viral infection transmitted by Aedes mosquitoes, is an emerging global health threat exacerbated by climate change. Rising temperatures and altered precipitation patterns create favourable conditions for vector proliferation and extended transmission periods, increasing the risk of dengue in endemic regions and facilitating its spread to non-endemic areas. Understanding the interplay between critical genetic factors and dengue susceptibility is crucial for developing effective public health strategies. The Human Leukocyte Antigen (HLA) genes encode proteins essential for an effective immune response against pathogens, and their genetic variations influence susceptibility to severe dengue. In this study, we conducted a comprehensive meta-analysis of HLA alleles associated with dengue infection and dengue severity. We analysed 19 case-control studies on dengue infections in populations worldwide to infer HLA associations with various pathological forms of dengue and to examine differences across different populations. Our findings indicate that HLA-A*02 increases susceptibility to dengue fever (DF), while HLA-A*03 increases the risk of Dengue Haemorrhagic Fever (DHF), with these increased susceptibilities primarily observed in Southeast Asian populations. Additionally, HLA-A*24 is associated with DHF and all symptomatic dengue infections (DEN), contributing to dengue risk in both Southeast Asia and the Caribbean. Conversely, HLA-A*33 and HLA-B*44 show a protective effect against DHF but show significant regional heterogeneity, highlighting divergent, population-specific susceptibility profiles. This study underscores the importance of population-specific genetic risk assessments for dengue infection and emphasizes the need for targeted medical interventions and improved predictive models to mitigate dengue's impact, especially as climate change accelerates disease spread.

Immune system gene polymorphisms associated with severe dengue in Latin America: a systematic review

One of the main challenges in the clinical management of dengue is the early identification of cases that could progress to severe forms of the disease. A biomarker that may enable this identification is the presence of genetic polymorphisms in genes associated with immune responses. The objective of this study was to perform a systematic review of the Latin American literature on these genes. An electronic literature search was carried out in PubMed, Scopus, Lilacs, and the Virtual Health Library, and reference lists of systematic reviews in the area. Case-control studies conducted in Latin American countries examining at least one form of genetic polymorphism related to immune responses against severe dengue were included. In total, 424 articles were identified and 26 were included in this systematic review. Of the 26 selected articles, 16 reported polymorphisms associated with the risk of developing severe dengue (Risk); Similarly, 16 articles reported polymorphisms associated with a decreased risk of severe dengue (Protective). The final analysis revealed that multiple polymorphisms in immune system genes were early markers of the progression of dengue in Latin Americans and found that polymorphisms of the TNF-alpha gene may have a critical role in dengue pathogenesis.

HLA-A, -B, -DRB1 Alleles as Genetic Predictive Factors for Dengue Disease: A Systematic Review and Meta-Analysis

Dengue virus infection (DEN) is one of the most prevalent arbovirus diseases in the tropical and subtropical areas. Some human leukocyte antigen (HLA) alleles have been reported to be a protective or risk factor to DEN. Due to the limited sample sizes and regional limitations, the results of individual studies were various. This meta-analysis aimed at investigating the relationship between HLA alleles and dengue disease. Relevant studies of the relationship between HLA and dengue disease were searched through PubMed, Embase, Web of science, and Cochrane databases. Subgroups according to ethnicity or sub-alleles and sensitivity analysis were used to explore the potential source of heterogeneity, which was performed to confirm the findings. The relationships between HLA and dengue disease were defined by odds ratios (ORs) with a 95% confidence interval (CI). Fourteen studies were finally confirmed. Results indicated that A*0203 (OR = 2.19, 95% CI = 1.30-3.69) and A*24 in the Asian group (OR = 1.44, 95% CI = 1.21-1.71) were positively associated with an increased risk of DEN when compared with normal controls. A*33 (OR = 0.49, 95% CI = 0.34-0.69) in Southeast Asia was negatively associated with DEN when compared with normal controls, suggesting a protective role against DEN. In addition, DRB1*11 (OR = 4.10, 95% CI = 1.23-13.69) was positively associated with severe dengue (SD) when compared with dengue fever, whereas DRB1*03 (OR = 0.48, 95% CI = 0.28-0.82) and DRB1*09 (OR = 0.73, 95% CI = 0.55-0.96) were negatively associated with SD when compared with normal controls. The meta-analysis confirmed that HLA-A*0203, A*24, A*33, DRB1*03, DRB1*09, and DRB1*11 have significantly affected dengue disease, and the associations are related to race and regions.

Clinical and immunological markers of dengue progression in a study cohort from a hyperendemic area in Malaysia

Background

With its elusive pathogenesis, dengue imposes serious healthcare, economic and social burden on endemic countries. This study describes the clinical and immunological parameters of a dengue cohort in a Malaysian city, the first according to the WHO 2009 dengue classification.

Methodology and Findings

This longitudinal descriptive study was conducted in two Malaysian hospitals where patients aged 14 and above with clinical symptoms suggestive of dengue were recruited with informed consent. Among the 504 participants, 9.3% were classified as non-dengue, 12.7% without warning signs, 77.0% with warning signs and 1.0% with severe dengue based on clinical diagnosis. Of these, 37% were misdiagnosed as non-dengue, highlighting the importance of both clinical diagnosis and laboratory findings. Thrombocytopenia, prolonged clotting time, liver enzymes, ALT and AST served as good markers for dengue progression but could not distinguish between patients with and without warning signs. HLA-A*24 and -B*57 were positively associated with Chinese and Indians patients with warning signs, respectively, whereas A*03 may be protective in the Malays. HLA-A*33 was also positively associated in patients with warning signs when compared to those without. Dengue NS1, NS2A, NS4A and NS4B were found to be important T cell epitopes; however with no apparent difference between with and without warning signs patients. Distinction between the 2 groups of patients was also not observed in any of the cytokines analyzed; nevertheless, 12 were significantly differentially expressed at the different phases of illness.

Conclusion

The new dengue classification system has allowed more specific detection of dengue patients, however, none of the clinical parameters allowed distinction of patients with and without warning signs. While the HLA-A*33 may be predictive marker for development of warning signs; larger studies will be needed to support this findings.