Association of increased platelet-associated immunoglobulins with thrombocytopenia and the severity of disease in secondary dengue virus infections

Severe thrombocytopenia and increased vascular permeability are two major characteristics of dengue haemorrhagic fever (DHF). To develop a better understanding of the roles of platelet-associated IgG (PAIgG) and IgM (PAIgM) in inducing thrombocytopenia and its severity of disease in patients with secondary dengue virus infection, the relationship between the PAIgG or PAIgM levels and disease severity as well as thrombocytopenia was examined in 78 patients with acute phase secondary infection in a prospective hospital-based study. The decrease in platelet count during the acute phase recovered significantly during the convalescent phase. In contrast, the increased levels of PAIgG or PAIgM that occurred during the acute phase of these patients decreased significantly during the convalescent phase. An inverse correlation between platelet count and PAIgG or PAIgM levels was found in these patients. Anti-dengue virus IgG and IgM activity was found in platelet eluates from 10 patients in an acute phase of secondary infection. Increased levels of PAIgG or PAIgM were significantly higher in DHF than those in dengue fever (DF). An increased level of PAIgM was associated independently with the development of DHF, representing a possible predictor of DHF with a high specificity. Our present data suggest that platelet-associated immunoglobulins involving antidengue virus activity play a pivotal role in the induction of thrombocytopenia and the severity of the disease in secondary dengue virus infections.     

Serodiagnosis of dengue virus infection in patients presenting to a tertiary care hospital

Dengue is an acute infectious disease of viral etiology. It is probably one of the most important arthropod borne viral disease in terms of human morbidity and mortality. The spectrum of disease ranges from self-limited dengue fever to more severe forms of dengue hemorrhagic fever (DHF) or dengue shock syndrome (DSS). Laboratory diagnosis of dengue virus infection mainly depends on detection of virus specific antibodies. The aim of the study was to correlate the serological results with clinical presentation in patients with a diagnosis of dengue. Eleven out of 15 (73.3%) patients with DHF and DSS had secondary antibody response and mortality was 100% in these patients.     

HLA-A and -B allele associations with secondary dengue virus infections correlate with disease severity and the infecting viral serotype in ethnic Thais

Little is known of the role of classical HLA-A and -B class I alleles in determining resistance, susceptibility, or the severity of acute viral infections. Appropriate paradigms for immunogenetic studies of acute viral infections are dengue fever (DF) and dengue hemorrhagic fever (DHF). Both primary and secondary infections with dengue virus (DEN) serotypes 1, 2, 3 or 4, can result in either clinically less severe DF or the more severe DHF. In secondary exposures, a memory response is induced in immunologically primed individuals, which can both clear the infecting dengue virus and contribute to its pathology. In a case-control study of 263 ethnic Thai patients infected with either DEN-1, -2, -3 or -4, we detected HLA class I associations with secondary infections, but not in immunologically naive patients with primary infections. HLA-A*0203 was associated with the less severe DF, regardless of the secondary infecting virus serotype. By contrast, HLA-A*0207 was associated with susceptibility to the more severe DHF in patients with secondary DEN-1 and DEN-2 infections only. Conversely, HLA-B*51 was associated with the development of DHF in patients with secondary infections, and HLA-B*52 was associated with DF in patients with secondary DEN-1 and DEN-2 infections. Moreover, HLA-B44, B62, B76 and B77 also appeared to be protective against developing clinical disease after secondary dengue virus infection. These results confirm that classical HLA class I alleles are associated with the clinical outcome of exposure to dengue virus, in previously exposed and immunologically primed individuals.     

Influenza and dengue virus co‐infection impairs monocyte recruitment to the lung,increases dengue virus titers,and exacerbates pneumonia

Co‐infections of influenza virus and bacteria are known to cause severe disease, but little information exists on co‐infections with other acute viruses. Seasonal influenza and dengue viruses (DENV) regularly co‐circulate in tropical regions. The pandemic spread of influenza virus H1N1 (hereafter H1N1) in 2009 led to additional severe disease cases that were co‐infected with DENV. Here, we investigated the impact of co‐infection on immune responses and pathogenesis in a new mouse model. Co‐infection of otherwise sublethal doses of a Nicaraguan clinical H1N1 isolate and two days later with a virulent DENV2 strain increased systemic DENV titers and caused 90% lethality. Lungs of co‐infected mice carried both viruses, developed severe pneumonia, and expressed a unique pattern of host mRNAs, resembling only partial responses against infection with either virus alone. A large number of monocytes were recruited to DENV‐infected but not to co‐infected lungs, and depletion and adoptive transfer experiments revealed a beneficial role of monocytes. Our study shows that co‐infection with influenza and DENV impairs host responses, which fail to control DENV titers and instead, induce severe lung damage. Further, our findings identify key inflammatory pathways and monocyte function as targets for future therapies that may limit immunopathology in co‐infected patients.     

Demonstration of concurrent dengue 1 and dengue 3 infection in six patients by the polymerase chain reaction

A dual viremia resulting from naturally acquired dengue 1 and dengue 3 infections in six patients experiencing a dengue-like syndrome during the epidemic in New Caledonia in 1989 is reported. Serotype identification was first based on virus isolation in mosquito cells and immunofluorescence using type-specific monoclonal antibodies. The double infection was confirmed directly in blood samples by the polymerase chain reaction (PCR) on genomic RNA and hybridization of the amplified cDNA fragments with type-specific DNA probes.     

Elevated plasma levels of the long pentraxin, pentraxin 3, in severe dengue virus infections

C-reactive protein is one of the most widely used indicators of the response of acute-phase proteins. The measurement of C-reactive protein in dengue, however, is clinically not useful, because of marginally elevated levels and absent association with disease severity. The prototypic long pentraxin, pentraxin 3, is an acute phase protein that is structurally related but distinct from C-reactive protein which has proven to correlate with the severity of bacterial infection in critically ill patients. The potential involvement of pentraxin 3 in dengue and its aptitude to predict more severe disease or poor clinical outcome has not been studied previously. We therefore measured pentraxin 3 plasma levels in 44 dengue virus infected patients. Pentraxin 3 levels were strikingly higher when compared to C-reactive protein levels, with highest pentraxin 3 values observed in the first 7 days after the onset of symptoms. Median pentraxin 3 levels at admission and peak levels during follow up were higher in patients suffering from dengue shock syndrome (at admission: 119.3 ng/ml [interquartile range 61.8--188.7], peak values during follow up: 147.9 ng/ml [interquartile range 85.7--204.3]) compared to levels found in patients with dengue fever and dengue hemorrhagic fever (at admission: 59.0 ng/ml [interquartile range 28.6--100.3], P=0.040; peak values during follow up: 80.8 ng/ml [interquartile range 36.1--168.1], P=0.020). Our results indicate that pentraxin 3 seems to be a marker of infection better than C-reactive protein in dengue. The role of pentraxin 3 in the pathogenesis of dengue and its potential as an early prognostic indicator of disease severity needs further assessment.     

Acute West Nile virus neuroinvasive infections: cross-reactivity with dengue virus and tick-borne encephalitis virus

Cross-reactions in serology are common among flaviviruses. During the outbreak of West Nile virus (WNV) infections in Greece in 2010, WNV IgM-positive serum and cerebrospinal fluid samples were tested for the presence of IgM and IgG antibodies against Dengue virus (DENV) and tick-borne encephalitis virus. Higher cross-reactivity was observed in IgM antibodies between WNV and DENV; however, the index of the WNV antibodies was in all cases higher than that of the DENV antibodies. There is a need for caution when evaluating serologic results of flaviviral infections, while efforts have to be focused on the development of diagnostic assays with increased specificity.     

Avidity determination of IgG directed against tick-borne encephalitis virus improves detection of current infections

Recently, avidity determination of IgG has been introduced successfully into virus serology as an additional and specific means for confirmation or exclusion of current infections. This simple and highly reproducible method can compensate for problems arising by classical serology, which include lack of detectable IgM responses during primary infections and persistent IgM responses after past infections. We show that avidity determination can be applied successfully for serological diagnosis of TBEV infection. Using the urea denaturation method, primary TBEV infections showed anti-TBEV IgG of low avidity (avidity index < 0.4), whereas sera from individuals with past infections exhibited high avidity IgG. The retrospective analysis of cases with clinical symptoms of TBEV infection in the absence of detectable anti-TBEV IgM showed that a significant number of these cases (5/45) had anti-TBEV IgG of low avidity, indicating current infection. We recommend the use of avidity determination as a method for routine TBEV serology. J. Med. Virol. 51:242–251, 1997. © 1997 Wiley-Liss, Inc.     

Nonstructural protein NS1 immunodominant epitope detected specifically in dengue virus infected material by a SELDI-TOF/MS based assay

Dengue virus (DV) infection is the most common mosquito-born viral disease of public health significance. Though most patients only suffer from flu-like symptoms, a small group of patients experiences more severe forms of the disease. The viral nonstructural protein 1 (NS1), a secreted protein correlating with viremia, is a key element used for dengue diagnosis with potential implications in severe dengue prognosis. Capture-ELISAs for the early detection of the NS1 protein in the sera during the acute febrile stage are commonly used in routine by diagnostic laboratories. In this study, the detection of NS1 protein in DV-infected material was assessed by an alternative method combining a single NS1-directed monoclonal antibody and the SELDI-TOF/MS technology. According to the epitope mapping, the antibodies used are mainly directed against an immuno-dominant peptide located on the C-terminal part of the protein. The NS1 SELDI-TOF assay is specific, has a sensitivity level close to capture-ELISAs and is potentially useful for a coupled serotyping/detection assay or for the detection of subtle post-translational modifications on the protein.     

Molecular characterization of dengue virus 1 from autochthonous dengue fever cases in Croatia

In the summer of 2010, two autochthonous dengue fever cases were detected in Croatia. Here we report the retrospective detection of an additional case of dengue fever, representing the first sustained autochthonous transmission in Europe since 1928. In addition, we present the phylogenetic analyses based on two sequences from the Pelje?ac peninsula, southern Croatia. The sequences were identified as dengue virus genotype 1 and recovered from two out of the three Pelje?ac patients in whom infection occurred.     

Modulation of immune responses in the central nervous system by Zika virus,West Nile virus,and dengue virus

Arthropod-borne viruses (arboviruses) pose significant threats to global public health by causing a spectrum of diseases ranging from mild febrile illnesses to severe neurological complications. Understanding the intricate interplay between arboviruses and the immune system within the central nervous system is crucial for developing effective strategies to combat these infections and mitigate their neurological sequelae. This review comprehensively explores the mechanisms by which arboviruses such as Zika virus, West Nile virus, and Dengue virus manipulate immune responses within the CNS, leading to diverse clinical manifestations.     

Maternal and neonatal anti‐cytomegalovirus IgG level and risk of postnatal cytomegalovirus transmission in preterm infants

Immunological mechanisms influencing the risk of mother‐to‐child cytomegalovirus (CMV) transmission in preterm infants have not been studied sufficiently. In this study, the correlation between maternal and neonatal serum anti‐CMV IgG levels and risk of postnatal CMV transmission in preterm infants was assessed. Anti‐CMV IgG levels of 79 CMV seropositive mothers and their 94 infants were determined in peripheral blood samples collected within 3 days after delivery. Postnatal CMV infection was detected in 39/94 (41%) infants by PCR on urine at term‐equivalent age (gestational age 40 weeks) after congenital infection was excluded. Maternal or infant anti‐CMV IgG levels were not significantly different between infants with and without postnatal CMV infection. The anti‐CMV IgG infant–mother ratio showed a significant positive correlation with gestational age (range 25–32 weeks, R² = 0.218, P < 0.001), reaching 1.0 at 32 weeks of gestation. Anti‐CMV IgG infant–mother ratio was significantly lower in infants with postnatal CMV infection (P = 0.015). In conclusion, the risk of postnatal CMV transmission is related to low gestational age and low anti‐CMV IgG infant–mother ratio. J. Med. Virol. 85:689–695, 2013. © 2013 Wiley Periodicals, Inc.     

Serum IgG subclass responses of humans to inactivated and live influenza A vaccines compared to natural infections with influenza A

Studies with various viral agents have suggested that a preferential production of IgG subclasses may occur during infection, but limited information has been reported on the IgG isotypes produced during vaccination with live or killed virus preparations. The serum IgG subclass responses to influenza A infection or inoculation with live or killed influenza A vaccines were examined by an enzyme-linked immunosorbent assay, and results were expressed using a 4-parameter logistic model. It was observed that IgG1 was induced by both natural infections and the live virus vaccine depending on the dose given. Inactivated vaccines induced significant titres of IgG1, IgG2, and IgG3 isotypes in vaccinees, again depending upon the amount of virus preparation administered.     

Mast cell–macrophage dynamics in modulation of dengue virus infection in skin

Dengue virus (DENV) infection causes dengue fever, dengue haemorrhagic fever, or dengue shock syndrome. Mast cells have been speculated to play a role in DENV disease although their precise roles are unclear. In this study, we used mast cell‐deficient Kit^{W‐sh/W‐sh} mice to investigate the involvement of mast cells after intradermal DENV infection. An approximately two‐ to three‐fold higher level of DENV NS3 antigen was detected at the skin inoculation site in DENV‐infected Kit^{W‐sh/W‐sh} mice than in DENV‐infected wild‐type (WT) mice (using a dose of 1 × 10⁹ plaque‐forming units/mouse). Moreover, as an indicator of heightened pathogenesis, a more prolonged bleeding time was observed in DENV‐infected Kit^{W‐sh/W‐sh} mice than in WT mice. Monocytes/macrophages are considered to be important targets for DENV infection, so we investigated the susceptibility and chemokine response of DENV‐infected peritoneal macrophages from Kit^{W‐sh/W‐sh} and WT mice both ex vivo and in vivo. There was a tendency for higher DENV infection and higher secretion of CCL2 (MCP‐1) from peritoneal macrophages isolated from Kit^{W‐sh/W‐sh} mice than those from WT mice. In vivo studies using intradermal inoculation of DENV showed about twofold higher levels of infiltrating macrophages and CCL2 (MCP‐1) at the inoculation site in both mock control and DENV‐inoculated Kit^{W‐sh/W‐sh} mice than in corresponding WT mice. In summary, compared with WT mice, Kit^{W‐sh/W‐sh} mice show enhanced DENV infection and macrophage infiltration at the skin inoculation site as well as increased DENV‐associated bleeding time. The results indicate an intriguing interplay between mast cells and tissue macrophages to restrict DENV replication in the skin.     

2008-2010年广州市自然界白纹伊蚊携带登革病毒监测

目的通过对广州地区登革热媒介蚊虫白纹伊蚊携带登革病毒情况的监测,探讨传播媒介对该地区登革热流行特征的影响。方法采集广州市各区新旧疫点附近的白纹伊蚊幼虫及成蚊,提取蚊虫总RNA,用登革病毒特异引物经实时荧光逆转录聚合酶链反应（RT-PCR）进行病毒核酸检测。结果 2008年以来共检测白纹伊蚊标本658批,合计12348只,平均每批检测18.8只蚊虫,未检测出登革病毒核酸。结论广州地区白纹伊蚊自然种群携带登革病毒水平较低。