Epidemiological and hematological investigation of Dengue Virus infection

Immune responses in children with secondary infection of mycoplasma pneumoniae after COVID-19: focus on eosinophils and IgE

BACKGROUND

The COVID-19 (SARS-CoV-2) epidemic has posed a major challenge to global public health, especially in children. Some children may experience secondary infection with Mycoplasma pneumoniae after SARS-CoV-2 infection, which has attracted widespread attention. Studies have shown that eosinophils play an important role in respiratory tract infections and are involved in regulating immune responses and inflammatory processes. However, there is a lack of systematic research on the specific manifestations and mechanisms of eosinophils in secondary infection with Mycoplasma pneumoniae after SARS-CoV-2 infection.

OBJECTIVE

This study aims to explore the characteristics of immune response in children with SARS-CoV-2 infection and Mycoplasma pneumoniae infection, focusing on the changes in immune indicators such as eosinophils (EOS), immunoglobulin E (IgE), interleukin-6 (IL-6), C-reactive protein (CRP), and procalcitonin (PCT).

METHODS

This study is a retrospective observational study, and a total of pediatric patients who were treated in our hospital from January 2023 to December 2023 were included. The study group included children who were diagnosed with SARS-CoV-2 infection and further infected with Mycoplasma pneumoniae, and the control group included children who were only infected with SARS-CoV-2 and had no other pathogens. The clinical data of the two groups of patients, including absolute eosinophil value, IgE quantification, IL-6, CRP and PCT levels, were collected and analyzed, and statistical comparisons were performed.

RESULTS

A total of 134 children were included, including 79 in the study group and 55 in the control group. The absolute eosinophil value [0.17 (0.09, 0.31) vs. 0.09 (0.06, 0.23), P < 0.01] and IgE level [59.28 (37.54, 256.88) vs. 22.00 (11.00, 113.10) P < 0.01] of the children in the study group were significantly higher than those in the control group, while IL-6 [16.81(4.72,31.86) vs. 9.5(3,57.3), P = 0.602], CRP [2.82(1.10,6.13) vs. 1.94(0.50,8.94), P = 0.528] and PCT[0.12(0.08,0.20) vs. 0.12(0.10,0.24), P = 0.329] were no significant difference between the two groups. Binary logistic regression analysis showed that the absolute value of eosinophils and IgE were independent risk factors for secondary infection of Mycoplasma pneumoniae after SARS-CoV-2 infection.

CONCLUSION

This study shows that after SARS-CoV-2 infection, the increase in eosinophils and the increase in related immune indicators IgE may be closely related to secondary infection with Mycoplasma pneumoniae. This study provides an important basis for understanding the immune response of children after SARS-CoV-2 infection and its related clinical management, suggesting that clinicians should closely monitor the eosinophil count and IgE level of children after SARS-CoV-2 infection, especially for children at risk of secondary infection, so as to take timely intervention measures to prevent secondary infection with Mycoplasma pneumoniae and improve the prognosis of children.

Dengue Mimickers: Which Clinical Conditions Can Resemble Dengue Fever?

Epidemics and outbreaks caused by the dengue virus pose risks to populations and have high mortality rates, causing burdens and economic costs worldwide. Brazil recently experienced an explosive increase in the number of dengue cases and fatalities. Dengue is an acute febrile illness that can progress to severe forms. It affects more than 100 countries, presenting ongoing challenges in Brazil and globally since its identification. Other conditions may be overlooked or mistaken for dengue. The most important differential diagnoses are other infectious diseases and rheumatological, hematological, gastroenterological, and neurological disorders. In this article, we discuss the primary differential diagnoses of dengue and offer a literature review highlighting the key clinical differences among clinicians. This review emphasizes the critical importance of differentiating dengue fever from infectious diseases such as meningococcemia and malaria and autoimmune and rheumatological conditions such as systemic lupus erythematosus to ensure timely and appropriate management.

Eosinophils as modulators of host defense during parasitic, fungal, bacterial, and viral infections

Eosinophils, traditionally associated as central innate effector cells with type 2 immunity during allergic and helminth parasitic diseases, have recently been revealed to have important roles in tissue homeostasis as well as host defense in a broader variety of infectious diseases. In a dedicated session at the 2023 biennial conference of the International Eosinophil Society titled "Eosinophils in Host Defense," the multifaceted roles eosinophils play against diverse pathogens, ranging from parasites to fungi, bacteria, and viruses, were presented. In this review, the session speakers offer a comprehensive summary of recent discoveries across pathogen classes, positioning eosinophils as pivotal leukocytes in both host defense and pathology. By unraveling the intricacies of eosinophil engagement in host resistance, this exploration may provide valuable insights not only to understand specific underpinnings of eosinophil functions related to each class of pathogens but also to develop novel therapeutics effective against a broad spectrum of infectious diseases.

Altered neutrophil responses to dengue virus serotype three: delayed apoptosis is regulated by stabilisation of Mcl-1

Dengue is a global health concern, and the host-viral interactions that regulate disease severity are largely unknown. Detrimental effects of neutrophils in this disease have been reported, but the precise mechanisms and functional properties of dengue-activated neutrophils are not fully characterised. Here, we measured the effects of dengue virus serotype 3 (DV3) on neutrophil lifespan and functions. We show that DV3 extends neutrophil survival with a significant proportion of cells surviving for 72 h post-incubation. These effects on neutrophil survival were greater than those observed by adding GM-CSF and TNF-α alone, but these cytokines enhanced survival induced by the virus. Enhanced reactive oxygen species (ROS) generation was observed following incubation with DV3 activation and this ROS production was enhanced by co-incubation with priming agents. In addition, DV triggered the enhanced IL-8 expression by the majority of neutrophils and a low percentage of cells were activated to express MCP-1 (CCL2). A low number of neutrophils showed increased co-expression of the migratory markers, CCR7 and CXCR4 which could promote their migration towards lymph nodes. DV3 significantly upregulated the BCL-XL gene at 3, 12, and 24 h, and the Mcl-1 gene at 12 h, following treatment. We also show that DV3 induces the Mcl-1 protein stabilization similar to GM-CSF. This report sheds new light on the mechanisms by which neutrophils may contribute to the pathology of dengue disease via delayed apoptosis and generation of pro-inflammatory molecules, and raises the possibility that dengue-activated neutrophils may play a role in activating cells of adaptive immunity.

Componential usage patterns in dengue 4 viruses reveal their better evolutionary adaptation to humans

There have been at least four types of dengue outbreaks in the past few years. The evolutionary characteristics of dengue viruses have aroused great concerns. The evolutionary characteristics of dengue 4 viruses are studied in the present study based on their base usage patterns and codon usage patterns. The effective number of codons and relative synonymous codon usage (RSCU) values of four types of dengue viruses were counted or calculated. The Kullback–Leibler (K–L) divergences of relative synonymous codon usage from dengue viruses to humans and the Kullback–Leibler divergences of amino acid usage patterns from dengue viruses to humans were calculated to explore the adaptation levels of dengue viruses. The results suggested that: (1) codon adaptation in dengue 4 viruses occurred through an evolutionary process from 1956 to 2021, (2) overall relative synonymous codon usage values of dengue 4 viruses showed more similarities to humans than those of other subtypes of dengue viruses, and (3) the smaller Kullback–Leibler divergence of amino acid usage and relative synonymous codon usage from dengue viruses to humans indicated that the dengue 4 viruses adapted to human hosts better. All results indicated that both mutation pressure and natural selection pressure contributed to the codon usage pattern of dengue 4 viruses more obvious than to other subtypes of dengue viruses and that the dengue 4 viruses adapted to human hosts better than other types of dengue viruses during their evolutionary process.