Dengue (DEN) virus is responsible for one of the most significant viral diseases in tropical countries. Monocytes/macrophages (Mo/M) are the major target cells for DEN virus. To determine the effects of the interaction between DEN virus and Mo/M, human monocyte cultures were infected with DEN virus type 2. Apoptosis and production of tumor necrosis factor-␣ (TNF-␣) and nitric oxide were measured in control and infected cultures. Virus was taken up by phagocytosis, but no membrane-coated pits at the virus attachment sites were observed. Increased number of apoptotic cells and increased production of TNF-␣ were observed in infected monocyte cultures. No increase in production of nitric oxide was observed. These results may be related to early primary viral infection, in which virus could induce apoptosis in monocytes, but monocytes may contribute to host defense mechanisms against virus by viral phagocytosis, phagocytosis of infected apoptotic cells, and the release of proinflammatory cytokines.

This study evaluated the levels of TNFalpha, IL-6, IL-1beta, nitric oxide (NO), CRP, C3 and apoptosis in 36 patients with dengue fever (DF), 34 patients with dengue haemorrhagic fever (DHF) and in virus-infected monocyte cultures. IL-6, TNFalpha, NO (nitrites) and CRP levels were increased and C3 diminished in patients with DF and DHF. IL-6, TNFalpha, CPR and C3 values were associated with disease severity (DHF). Nitrite content was incremented in DF patients. TNFalpha, NO and CRP levels were associated with secondary infection. IL-6 and CRP levels were associated with dengue virus type 4 (DENV-4) and DENV-2, respectively. Low levels of C3 were associated with DENV-2 and DENV-4 infections. Similarly, increased content of TNFalpha, IL-6 and nitrites were observed in supernatants from infected monocyte cultures. IL-6 was associated with DENV-4 infection. The different virus serotypes induced apoptosis in monocyte cultures. Dengue infection did not induce elevated IL-1beta production, either in patients or in infected cultures. These results suggest that TNFalpha, IL-6, NO and CRP are involved in dengue infection and that monocytes could be an important source of cytokine and NO production.

Abstract. Nitric oxide (NO) has been involved in several infectious diseases. Virus dengue is capable of inducing increased levels of NO when cocultured with human Kupffer and spleen cells. However, no reports describe the levels of NO in patients with dengue infection. Increased levels of NO were found in patients with the classic form of the disease; however, in the hemorrhagic form of the disease, similar levels to those of healthy controls were found. In vitro studies showed no increased levels of NO when human platelets were incubated with the virus. Increased NO in classical dengue could be important in the evolution from the nonhemorrhagic to the hemorrhagic forms of dengue.

We determined the influence of melatonin (MLT) on the induction of interleukin (IL)-2, IL-1 beta, IL-4, tumour necrosis factor-alpha (TNF-alpha) and gamma interferon (IFN-gamma) on mice infected with the Venezuelan equine encephalomyelitis (VEE) virus. Levels of IFN-gamma in the MLT-treated group were significantly increased (P < 0.001) when compared with the control non-infected group from day 1 to 6 post-infection (p.i.), while in infected mice treated with 500 micrograms MLT/kg of bodyweight enhanced levels of IFN-gamma were evident from 4 to 6 days p.i. No differences were detected in the levels of IL-2 between the controls, the infected mice treated with MLT and the infected untreated group, from day 2 p.i. No changes in serum levels of IL-4 were detected. In infected mice treated with MLT, blood levels of IL-1 beta were elevated almost 10-fold from day 1 to day 6 p.i. when compared to the control, the infected and the non-infected MLT-treated mice (P < 0.001). A highly significant rise (P < 0.001) of TNF-alpha was found in infected mice treated with MLT, from day 1 to 6 p.i. when compared to the other groups. A significant rise (P < 0.001) was also evident in the infected non-MLT-treated group and a less pronounced rise in the non-infected mice treated with MLT when compared to controls. The blockade of IFN-gamma and TNF-alpha did not inhibit the protective effect of MLT but when IL-1 beta was neutralized, 100% of the infected mice died suggesting that IL-1 beta induced by MLT treatment is a target cytokine to generate an immune response against the viral infection.

Neurological damage during brain Venezuelan equine encephalitis virus infection could be mediated by apoptosis and oxidative stress and CD200 molecule could be an important anti-inflammatory response. Melatonin could be beneficial reducing apoptosis and oxidative stress.

Abstract. We describe sequences of six strains of dengue virus (DENV): three DENV-1 isolates and two DENV-4 isolates from Puerto Rico, and a DENV-1 strain from Key West, Florida, obtained from blood donors during 2010 epidemics. Phylogenetic analysis revealed that the Puerto Rico DENV-1 strains constitute a new lineage within genotype V different from those that circulated in Puerto Rico during the past two decades. The newer Puerto Rico DENV-1 strains associated with strains from the Caribbean and South America. The DENV-1 strain from Key West, Florida clustered with a strain isolated from mosquito pools collected in that area and with a number of strains from Nicaragua and Mexico circulating during 2006-2009. The Puerto Rico DENV-4 isolates of genotype II associated with strains that have circulated on the island throughout the 1980s and 1990s and with strains from the Caribbean region and Central America. Introduction and circulation of novel DENV lineages in dengue-endemic regions have the potential to increase the severity of dengue cases.Dengue is caused by any of the four dengue virus types (DENV-1 to DENV-4), family Flaviviridae, genus Flavivirus. Dengue virus is primarily transmitted by the urban mosquito Aedes aegypti and most dengue infections are asymptomatic or sub-clinical. Dengue disease spectrum ranges from a mild, influenza-like disease (dengue fever) to a potentially lifethreatening condition known as severe dengue/dengue hemorrhagic fever. 1The four DENV types are genetically distant from each other, and phylogenetic analysis shows epidemic genotypes that vary in number and geographic distribution depending on the DENV type. Additionally, sylvatic cycles exist in Africa and Asia where sylvatic strains of DENV-2 and DENV-4 have been isolated from arboreal mosquitoes, humans, and non-human primates.2 Four DENV-1 epidemic genotypes (I, II, IV, and V) and a sylvatic genotype have been described. However, for the sylvatic genotype recent evidence suggest a human origin, therefore being included as genotype III in newer classifications. Conversely, for DENV-4, three epidemic genotypes (I-III) and a sylvatic genotype have been described.3 Some DENV genotypes have shown to be more virulent, with better fitness, and have been associated with increased clinical severity of dengue cases (e.g., American/ Asian genotype of DENV-2). 4In the United States, dengue is endemic to the Commonwealth of Puerto Rico, which in 2010 experienced the largest epidemic in its history with more than 21,000 dengue suspected cases reported, of which approximately 75% were laboratory confirmed.5 Sporadic dengue outbreaks have occurred in the Territories of Guam and American Samoa, the States of Hawaii and Texas, 6-8 and more recently in Key West, Florida during 2009-2011. 9,10 We report sequences and phylogenetic analyses of three DENV-1 and two DENV-4 strains isolated from Puerto Rico and a DENV-1 strain from Key West, Florida circulating during the 2010 epidemics.Six plasma samples obtained from blood donors infected with...

BackgroundRespiratory viral infections can induce different cytokine/chemokine profiles in lung tissues and have a significant influence on patients with asthma. There is little information about the systemic cytokine status in viral respiratory-infected asthmatic patients compared with non-asthmatic patients.ObjectivesThe aim of this study was to determine changes in circulating cytokines (IL-1β, TNF-α, IL-4, IL-5) and chemokines (MCP1: monocyte chemoattractant protein-1 and RANTES: regulated on activation normal T cell expressed and secreted) in patients with an asthmatic versus a non-asthmatic background with respiratory syncytial virus, parainfluenza virus or adenovirus respiratory infection. In addition, human monocyte cultures were incubated with respiratory viruses to determine the cytokine/chemokine profiles.Patients/MethodsPatients with asthmatic (n = 34) and non-asthmatic (n = 18) history and respiratory infections with respiratory syncytial virus, parainfluenza, and adenovirus were studied. Healthy individuals with similar age and sex (n = 10) were used as controls. Cytokine/chemokine content in blood and culture supernatants was determined by ELISA. Monocytes were isolated by Hystopaque gradient and cocultured with each of the above-mentioned viruses.ResultsSimilar increased cytokine concentrations were observed in asthmatic and non-asthmatic patients. However, higher concentrations of chemokines were observed in asthmatic patients. Virus-infected monocyte cultures showed similar cytokine/chemokine profiles to those observed in the patients.ConclusionsCirculating cytokine profiles induced by acute viral lung infection were not related to asthmatic status, except for chemokines that were already increased in the asthmatic status. Monocytes could play an important role in the increased circulating concentration of cytokines found during respiratory viral infections.

Increased expression of inducible nitric oxide synthase has been shown in murine Venezuelan equine encephalitis (VEE) virus infection. In this experimental model, melatonin (MTL) treatment has shown to be beneficial. The aim of this study was to determine the effect of VEE virus on the nitric oxide (NO) production and lipid peroxidation in neuroblastoma cell cultures, and to investigate the role of MTL during cell-virus interaction. Neuroblastoma cells were co-cultured with VEE virus and treated with MTL at doses ranging from 0 to 1.8 mM, for 6, 12, 24 and 48 h. NO and lipid peroxidation were measured in culture supernatants and in the cellular content by nitrite concentration and thiobarbituric acid assay, respectively. Expression of inducible nitric oxide synthase (iNOS) was determined by indirect immunofluorescence. Increased production of NO and lipid peroxidation products were found in supernatants and cellular contents of VEE virus treated cultures. Both NO and lipid peroxidation were decreased by MTL treatment in a time dependent manner. Increased iNOS expression was observed in VEE virus infected cultures that was reduced by MTL treatment. These results could be related to the beneficial role of MTL in the VEE experimental disease and address the possible therapeutic potential of the hormone in human VEE virus infection.