Sergio Isaac De La Cruz Hernández

The 1α,25-dihydroxy-vitamin D3 reduces dengue virus infection in human myelomonocyte (U937) and hepatic (Huh-7) cell lines and cytokine production in the infected monocytes.

Dengue is the most important mosquito-borne viral infection in humans. Recent evidence suggests that vitamin D influences virus replication. In this work, the effect of vitamin D treatment on dengue virus infection in human hepatic Huh-7 cells and on virus infection and cytokine production in the human monocytic U937 cells was evaluated. Exposure to 1α,25-dihydroxy-vitamin D3, resulted in a significant reduction in the number of infected cells, in conditions where cell viability was not affected. Viral replication in monocytic cells was more susceptible to vitamin D3 than replication in the hepatic cells. Moreover, vitamin D3 significantly reduced the levels of proinflammatory cytokines (TNF-α, IL-6, IL-12p70 and IL-1β) produced by infected U937 cells. These results suggest that vitamin D3 may represent a potentially useful antiviral compound.

Evaluation of a novel commercial rapid test for dengue diagnosis based on specific IgA detection

The performance of the novel commercial test ASSURE® Dengue IgA Rapid test (MP Diagnostics) was evaluated using a panel of 172 sera collected from dengue patients and 47 sera from healthy blood donors. The overall specificity and sensitivity were 61.0% and 85.1%, respectively. However, the positivity rate for IgA went from 33.3% for sera collected the same day of fever onset to 81.2% for sera collected 5 days after fever onset. Infections with serotype 2 viruses were detected more efficiently than those with serotype 1 viruses, and no sera from infections with serotypes 3 and 4 were available. In addition, the kit was twice more efficient at detecting secondary infections than at detecting primary infections. Finally, the ASSURE® test showed good repeatability and reproducibility. The results of this study suggest that the ASSURE® Dengue IgA Rapid test may become a useful and easy-to-use test for early dengue diagnosis.

Primary dengue virus infections induce differential cytokine production in Mexican patients

Severe dengue pathogenesis is not fully understood, but high levels of proinflammatory cytokines have been associated with dengue disease severity. In this study, the cytokine levels in 171 sera from Mexican patients with primary dengue fever (DF) and dengue haemorrhagic fever (DHF) from dengue virus (DENV) 1 (n = 116) or 2 (n = 55) were compared. DF and DHF were defined according to the patient’s clinical condition, the primary infections as indicated by IgG enzymatic immunoassay negative results, and the infecting serotype as assessed by real-time reverse transcription-polymerase chain reaction. Samples were analysed for circulating levels of interleukin (IL)-12p70, interferon (IFN)-γ, tumour necrosis factor (TNF)-α, IL-6, and IL-8 using a commercial cytometric bead array. Significantly higher IFN-γ levels were found in patients with DHF than those with DF. However, significantly higher IL-12p70, TNF-α, and IL-6 levels were associated with DHF only in patients who were infected with DENV2 but not with DENV1. Moreover, patients with DF who were infected with DENV1 showed higher levels of IL-12p70, TNF-α, and IL-6 than patients with DHF early after-fever onset. The IL-8 levels were similar in all cases regardless of the clinical condition or infection serotype. These results suggest that the association between high proinflammatory cytokine levels and dengue disease severity does not always stand, and it once again highlights the complex nature of DHF pathogenesis.

Real-time RT-PCR, a necessary tool to support the diagnosis and surveillance of rotavirus in Mexico

Rotavirus produces diarrhea in children under 5 years old. Most of those conventional methods such as polyacrylamide gel electrophoresis (PAGE) and reverse transcription-polymerase chain reaction (RT-PCR) have been used for rotavirus detection. However, these techniques need a multi-step process to get the results. In comparison with conventional methods, the real-time RT-PCR is a highly sensitive method, which allows getting the results in only one day. In this study a real-time RT-PCR assay was tested using a panel of 440 samples from patients with acute gastroenteritis, and characterized by PAGE and RT-PCR. The results show that the real-time RT-PCR detected rotavirus from 73% of rotavirus-negative samples analyzed by PAGE and RT-PCR; thus, the percentage of rotavirus-positive samples increased to 81%. The results indicate that this real-time RT-PCR should be part of a routine analysis, and as a support of the diagnosis of rotavirus in Mexico.

A one-step real-time RT-PCR helps to identify mixed rotavirus infections in Mexico

Rotaviruses continue being the most important pathogens responsible of diarrhea in young children worldwide. Seminested reverse transcription polymerase chain reaction (RT-PCR) is used to determine rotavirus genotype; however, this technique employs multistep procedures. The real-time RT-PCR is a fast and reliable tool that can be used as rotavirus genotyping tool, especially in rotavirus outbreaks. In this study, we tested a real-time RT-PCR to identify rotavirus genotype using a panel of 252 samples from patients with diarrheal disease caused by G9P[4] and G12P[8] genotypes, which were identified as emerging rotaviruses in 2 outbreaks in Chiapas, Mexico. Our results show that the real-time RT-PCR assay detected these rotaviruses, and it allowed us to identify mixed genotype infections, G/P combinations, and the viral abundance in some samples in which the seminested assay could not identify them. Therefore, the real-time RT-PCR is a molecular tool that can be great support during rotavirus outbreaks.