Correlations between genetic polymorphism of IFN-λ family gene and HBV infection, virus replication and clearance / 生物工程学报

Hepatitis B virus (HBV) infection is one of the most serious public health problems. HBV infection could lead to hepatitis B, and even further develop into hepatic cirrhosis and hepatocellular carcinoma. Interferon lambda (IFN-λ) is a member of the interferon (IFN) family and an important cytokine for antiviral defense. There are four members in IFN-λ family, including IFN-λ1, IFN-λ2, IFN-λ3, and IFN-λ4. The genetic polymorphisms in the IFN-λ genes are associated with HBV replication and treatment response of HBV patients. In this review, we summarized the roles of genetic polymorphisms of the IFN-λ genes played in HBV infection, disease progression and treatment, with the aim to better understand their function. This review could serve as a reference for the HBV prevention and treatment of HBV patients, as well as for future clinical usage.

Differential replicative fitness of the four dengue virus serotypes circulating in Colombia in human liver Huh7 cells

ABSTRACT Dengue has been a significant public health problem in Colombia since the simultaneous circulation of the four dengue virus serotypes. The replicative fitness of dengue is a biological feature important for virus evolution and contributes to elucidating the behavior of virus populations and viral pathogenesis. However, it has not yet been studied in Colombian isolates. This study aimed to compare the replicative fitness of the four dengue virus serotypes and understand the association between the serotypes, their in vitro infection ability, and their replication in target cells. We used three isolates of each DENV serotype to infect Huh-7 cells at an MOI of 0.5. The percentage of infected cells was evaluated by flow cytometry, cell viability was evaluated by MTT assay, and the pathogenicity index was calculated as a ratio of both parameters. The replicative fitness was measured by the number of viral genome copies produced using quantitative PCR and the production of infectious viral progeny was measured by plaque assay. We showed that Huh-7 cells were susceptible to infection with all the different strain isolates. Nevertheless, the biological characteristics, such as infectious ability and cell viability, were strain-dependent. We also found different degrees of pathogenicity between strains of the four serotypes, representative of the heterogeneity displayed in the circulating population. When we analyzed the replicative fitness using the mean values obtained from RT-qPCR and plaque assay for the different strains, we found serotype-dependent behavior. The highest mean values of replicative fitness were obtained for DENV-1 (log 4.9 PFU/ml) and DENV-4 (log 5.28 PFU/ml), followed by DENV-2 (log 3.9 PFU/ml) and DENV-3 (log 4.31 PFU/ml). The internal heterogeneity of the replicative fitness within each serotype could explain the simultaneous circulation of the four DENV serotypes in Colombia.

Development and characterization of a packaging cell line for pseudo-infectious yellow fever virus particle generation

Abstract INTRODUCTION: Pseudo-infectious yellow fever viral particles (YFV-PIVs) have been used to study vaccines and viral packaging. Here, we report the development of a packaging cell line, which expresses the YFV prM/E proteins. METHODS: HEK293 cells were transfected with YFV prM/E and C (84 nt) genes to generate HEK293-YFV-PrM/E-opt. The cells were evaluated for their ability to express the heterologous proteins and to package the replicon repYFV-17D-LucIRES, generating YFV-PIVs. RESULTS: The expression of prM/E proteins was confirmed, and the cell line trans-packaged the replicon for recovery of a reporter for the YFV-PIVs. CONCLUSIONS: HEK293-YFV-prM/E-opt trans-packaging capacity demonstrates its possible biotechnology application.

Avances en la investigación del virus dengue en Colombia: papel de los microARNs celulares en la respuesta anti-dengue virus / Advances in dengue virus research in Colombia: the role of cellular microRNAs as an anti-dengue virus response

Dengue is one of the most important mosquito-borne diseases, and its incidence has increased at an alarming rate in recent years, becoming a real public health problem. Currently, there is no vaccine or medication or proper treatment for dengue control. Considering this situation, it is necessary to prioritize the search for new alternatives and strategies for dengue prevention and control, in order to reduce not only the economic burden of endemic countries, but also to improve the quality of life of patients. In this regard, a brief reflection on some aspects related to the search for new alternatives in Colombia is presented. This is focused on the use of microRNAs, which could be a new strategy with great therapeutic potential.

El dengue es una de las enfermedades más importantes transmitidas por mosquitos y su incidencia ha aumentado a un ritmo alarmante en los últimos años, al punto que se ha convertido en un verdadero problema de salud pública. Actualmente no existe ni vacuna, ni un medicamento o tratamiento adecuado para el control del dengue. Con dichos antecedentes, es necesario priorizar en la búsqueda de nuevas alternativas o estrategias de control y prevención del dengue con miras a disminuir no sólo la carga económica de los países endémicos, sino también a mejorar la calidad de vida de los pacientes. En este sentido, se presenta una breve reflexión sobre algunos aspectos relacionados con la búsqueda de nuevas alternativas en Colombia, enfocadas en el uso de los microARNs, que podrían constituir una nueva estrategia con un gran potencial terapéutico, dado que tendrían el potencial de contrarrestar algunas infecciones virales crónicas.

Overexpression of miR-484 and miR-744 in Vero cells alters Dengue virus replication

BACKGROUND Dengue is considered one of the world’s most important mosquito-borne diseases. MicroRNAs (miRNAs) are small non-coding single-stranded RNAs that play an important role in the regulation of gene expression in eukaryotes. Although miRNAs possess antiviral activity against many mammalian-infecting viruses, their involvement in Dengue virus (DENV) replication remains poorly understood. OBJECTIVE To determine the role of miR-484 and miR-744 in DENV infection and to examine whether DENV infection alters the expression of both miRNAs. METHODS We used bioinformatics tools to explore the relationship between DENV and cellular miRNAs. We then overexpressed miR-484 or miR-744 in Vero cells to examine their role in DENV replication using flow cytometry, reverse transcriptase quantitative polymerase chain reaction (RT-qPCR), and western blotting. FINDINGS We found several cellular miRNAs that target a conserved region within the 3′ untranslated region (3′ UTR) of the genome of the four DENV serotypes and found that overexpression of miR-484 or miR-744 inhibits infection by DENV-1 to DENV-4. Furthermore, we observed that DENV RNA might be involved in the downregulation of endogenous miR-484 and miR-744. CONCLUSION Our study identifies miR-484 and miR-744 as two possible restriction host factors against DENV infection. However, further studies are needed to directly verify whether miR-484 and miR-744 both have an anti-DENV effect in vivo.

Anticuerpos policlonales contra la proteína recombinante NS3 del virus del dengue / Polyclonal antibodies against recombinant dengue virus NS3 protein

Resumen Introducción: El dengue es una enfermedad causada por uno de los cuatro serotipos del virus del dengue (DENV) y es endémica en, aproximadamente, 130 países. Su incidencia ha aumentado notablemente en las últimas décadas, así como la frecuencia y la magnitud de los brotes. A pesar de los esfuerzos, no existen tratamientos profilácticos ni terapéuticos contra la enfermedad y, en ese contexto, el estudio de los procesos que gobiernan el ciclo de infección del DENV es esencial para desarrollar vacunas o terapias antivirales. Una de las moléculas del DENV más prometedoras es la proteína no estructural 3 (NS3), la cual es indispensable para la replicación viral y es uno de los principales blancos inmunológicos durante la infección. Objetivo: Producir anticuerpos policlonales para contribuir a los futuros estudios sobre las interacciones entre la proteína NS3 y otras proteínas celulares. Materiales y métodos: Se expresaron dos proteínas recombinantes del dominio helicasa de NS3 del DENV de serotipo 2, las cuales se emplearon para inmunizar ratas y producir anticuerpos policlonales. Resultados: Los anticuerpos producidos fueron útiles en ensayos de Western blot e inmunofluorescencia y se reportó por primera vez un anticuerpo policlonal anti-NS3 que permitió la inmunoprecipitación de la proteína viral y la detecta con Western blot sin necesidad de inducir sobreexpresión de NS3 o de usar extractos de células marcados metabólicamente con radioisótopos. Conclusión: Las proteínas recombinantes expresadas y los anticuerpos producidos constituyen herramientas valiosas para estudiar procesos infecciosos del DENV que involucren a la proteína NS3 y evaluar pruebas dirigidas a interferir las funciones de esta proteína.

Abstract Introduction: Dengue is a disease caused by one of four serotypes of the dengue virus (DENV) and is endemic in approximately 130 countries. The incidence of dengue has increased dramatically in recent decades, as well as the frequency and magnitude of outbreaks. Despite all efforts, there are no prophylactic or therapeutic treatments for the disease. Accordingly, research on the processes governing the DENV infection cycle is essential to develop vaccines or antiviral therapies. One of the most attractive DENV molecules to investigate is nonstructural protein 3 (NS3), which is essential for viral replication and a major immune target for infection. Objective: To produce antibodies to support future studies on NS3 and its cellular interactions with other proteins. Materials and methods: Two recombinant proteins of the helicase domain of DENV NS3 serotype 2 were expressed, and used to immunize mice and produce polyclonal antibodies. Results: The antibodies produced were useful in Western blot and immunofluorescence tests. We report an NS3 antibody that immunoprecipitates the viral protein and detects it in Western blot with no need to over-express it or use cell extracts with metabolic radiolabeling.

Evaluation of short-interfering RNAs treatment in experimental rabies due to wild-type virus

ABSTRACTWe have evaluated the efficacy of short-interfering RNAs targeting the nucleoprotein gene and also the brain immune response in treated and non-treated infected mice. Mice were inoculated with wild-type virus, classified as dog (hv2) or vampire bat (hv3) variants and both groups were treated or leaved as controls. No difference was observed in the lethality rate between treated and non-treated groups, although clinical evaluation of hv2 infected mice showed differences in the severity of clinical disease (p = 0.0006). Evaluation of brain immune response 5 days post-inoculation in treated hv2 group showed no difference among the analyzed genes, whereas after 10 days post-inoculation there was increased expression of 2',5'-oligoadenylate synthetase 1, tumor necrosis factor alpha, interleukin 12, interferon gamma, and C-X-C motif chemokine 10 associated with higher expression of Ngene in the same period (p < 0.0001). In hv2 non-treated group only higher interferon beta expression was found at day 5. The observed differences in results of the immune response genes between treated and non-treated groups is not promising as they had neither impact on mortality nor even a reduction in the expression of N gene in siRNA treated animals. This finding suggests that the use of pre-designed siRNA alone may not be useful in rabies treatment.

The role of microRNAs in enteroviral infections

ABSTRACTThe genus Enterovirus, a member of thePicornavirus family, are RNA viruses that can cause poliomyelitis, hand-food-mouth disease, viral meningitis or meningoencephalitis, viral myocarditis and so on. MicroRNAs are a class of highly conserved, small noncoding RNAs recognized as important regulators of gene expression. Recent studies found that MicroRNAs play a significant role in the infection ofEnterovirus, such as enterovirus 71, coxsackievirus B3 and other Enterovirus. Enteroviral infection can alter the expression of cellular MicroRNAs, and cellular MicroRNAs can modulate viral pathogenesis and replication by regulating the expression level of viral or host's genes. Herein, this review summarizes the role of MicroRNAs in enteroviral infection.

Fluorescent antibody test, quantitative polymerase chain reaction pattern and clinical aspects of rabies virus strains isolated from main reservoirs in Brazil

ABSTRACTRabies virus (RABV) isolated from different mammals seems to have unique characteristics that influence the outcome of infection. RABV circulates in nature and is maintained by reservoirs that are responsible for the persistence of the disease for almost 4000 years. Considering the different pattern of pathogenicity of RABV strains in naturally and experimentally infected animals, the aim of this study was to analyze the characteristics of RABV variants isolated from the main Brazilian reservoirs, being related to a dog (variant 2),Desmodus rotundus (variant 3), crab eating fox, marmoset, and Myotis spp. Viral replication in brain tissue of experimentally infected mouse was evaluated by two laboratory techniques and the results were compared to clinical evolution from five RABV variants. The presence of the RABV was investigated in brain samples by fluorescent antibody test (FAT) and real time polymerase chain reaction (qRT-PCR) for quantification of rabies virus nucleoprotein gene (N gene). Virus replication is not correlated with clinical signs and evolution. The pattern of FAT is associated with RABV replication levels. Virus isolates from crab eating fox and marmoset had a longer evolution period and higher survival rate suggesting that the evolution period may contribute to the outcome. RABV virus variants had independent characteristics that determine the clinical evolution and survival of the infected mice.

Toll-like receptor 3 (TLR3) and the development of type 1 diabetes mellitus

Type 1 diabetes mellitus (T1DM) is a chronic, progressive autoimmune disease characterized by metabolic decompensation often leading to dehydration and ketoacidosis. Viral agents seem to play an important role in triggering the autoimmune destruction that leads to the development of T1DM. Among several viral strains investigated so far, the enterovirus family has been consistently associated with the onset of T1DM in humans. One of the mediators of viral damage is the double-stranded RNA (dsRNA) generated during replication and transcription of viral RNA and DNA. The Toll-like receptor 3 (TLR3) gene codes for an endoplasmic receptor of the pattern-recognition receptors (PRRs) family that recognizes dsRNA, plays an important role in the innate immune response triggered by viral infection. Binding of dsRNA to the TLR3 triggers the release of proinflammatory cytokines, such as interferons, which exhibit potent antiviral action; thus, protecting uninfected cells and inducing apoptosis of infected ones. Therefore, the TLR3 gene is a good candidate for the development of T1DM. Within this context, the objective of the present review was to address the role of the TLR3 gene in the development of T1DM. Arch Endocrinol Metab. 2015;59(1):4-12.

Construction and characterisation of a complete reverse genetics system of dengue virus type 3

Dengue virulence and fitness are important factors that determine disease outcome. However, dengue virus (DENV) molecular biology and pathogenesis are not completely elucidated. New insights on those mechanisms have been facilitated by the development of reverse genetic systems in the past decades. Unfortunately, instability of flavivirus genomes cloned in Escherichia coli has been a major problem in these systems. Here, we describe the development of a complete reverse genetics system, based on the construction of an infectious clone and replicon for a low passage DENV-3 genotype III of a clinical isolate. Both constructs were assembled into a newly designed yeast- E. coli shuttle vector by homologous recombination technique and propagated in yeast to prevent any possible genome instability in E. coli . RNA transcripts derived from the infectious clone are infectious upon transfection into BHK-21 cells even after repeated passages of the plasmid in yeast. Transcript-derived DENV-3 exhibited growth kinetics, focus formation size comparable to original DENV-3 in mosquito C6/36 cell culture. In vitro characterisation of DENV-3 replicon confirmed its identity and ability to replicate transiently in BHK-21 cells. The reverse genetics system reported here is a valuable tool that will facilitate further molecular studies in DENV replication, virus attenuation and pathogenesis.

Vaccinia virus regulates expression of p21WAF1/Cip1 in A431 cells

In this paper, we provide evidence that both the mRNA and protein levels of the cyclin-dependent kinase (CDK) inhibitor p21WAF1/CDK-interacting protein 1 (Cip1) increase upon infection of A431 cells with Vaccinia virus (VACV). In addition, the VACV growth factor (VGF) seems to be required for the gene expression because infection carried out with the mutant virus VACV-VGF- revealed that this strain was unable to stimulate its transcription. Our findings are also consistent with the notion that the VGF-mediated change in p21WAF1/Cip1 expression is dependent on tyrosine kinase pathway(s) and is partially dependent on mitogen-activated protein kinase/extracellular-signal regulated kinase 1/2. We believe that these pathways are biologically significant because VACV replication and dissemination was drastically affected when the infection was carried out in the presence of the relevant pharmacological inhibitors.

Hepatitis B virus genetic diversity and mutant / 대한간학회지

Hepatitis B virus (HBV) is a partially double stranded DNA virus with genetic diversity represented by eight genotypes (A to H). Natural course and response to treatment could be affected by HBV genotypes. HBV shows high rates of turn over in the absence of proof-reading ability. As a result, large amounts of quasispecies are produced naturally or antiviral-associated. HBV consists of four open reading frames, namely preS/S gene, precore/core gene, polymerase gene, and X gene. Mutations on preS gene can result in undetectable HBsAg even in case that HBV is replicating. Surface gene mutation leads to decreased binding affinity to anti-HBs, which is associated with a vaccine escape mutant. Precore mutation abolishes HBeAg whereas mutations on basal core promoter gene down-regulate the HBeAg production. Mutations on basal core promoter are associated with increased HBV replication and high incidence of progressive liver diseases such as liver cirrhosis and hepatocellular carcinoma. Mutations on polymerase genes are often induced by antiviral therapy. Emergence of antiviral-resistant mutation is the major cause of treatment failure. Furthermore, existence of prior antiviral-resistant mutations limits the options of subsequent antiviral agents. Therefore, judicious use of antivirals and selection of the most potent drug with the lowest resistance rate are of the utmost importance for the prevention of antiviral-associated mutants. Detailed knowledge and understanding of HBV genetic diversity and mutant would be critical to establish strategies for the diagnosis and management of HBV infection.

Short-interfering RNAs as antivirals against rabies

This study aimed to test in vitro a RNA-interference based antiviral approach for rabies with short-interfering RNAs (siRNAs) against rabies virus nucleoprotein mRNA. BHK-21 cells were infected with serial dilutions of PV rabies virus strain and transfected with a pool of three siRNAs. Direct immunofluorescence staining showed a 5-time decrease in virus titer when compared to a non-treated plate, showing a promising new approach to the development of antivirals for rabies treatment.

Replicacion del hipervirus equino y su asociacion con la patogenesis molecular / Equine Herpesvirus Replication and It’s Association with Molecular Pathogenesis

El herpesvirus equino (EHV) es uno de los patógenos virales de mayor importancia en la industria equina mundial, debido a las grandes pérdidas económicas que acarrea. La enfermedad comúnmente asociada con el EHV se denomina rinoneumonitis equina y se caracteriza por ser una infección primaria del tracto respiratorio superior, que progresa a través de la mucosa; puede causar aborto en los últimos meses de gestación, muerte perinatal de potros, mortinatos y mieloencefalitis. La infección productiva es seguida por un estado de latencia viral, etapa en la cual el animal no presenta ningún signo clínico de enfermedad y no hay replicación viral. Bajo una situación de estrés, el virus puede reactivarse y caballos infectados infectar a otros caballos sanos. En esta revisión se presenta de manera sintetizada, los principales hallazgos relacionados con la replicación viral y patogénesis molecular del EHV, relacionando además las proteínas implicadas en la regulación de la replicación del genoma, todas las glicoproteínas estructurales que han sido estudiadas hasta el momento y que son el eje central de investigación de distintos grupos en el mundo. Se discute además, la verdadera importancia de la dispersión directa célulacélula del virus, la formación de placas, el crecimiento in vitro y en algunos casos, la asociación con la patogénesis, bien sea en un modelo animal o en el hospedero natural.

The role of the Tat gene in the pathogenesis of HIV infection.

The human immunodeficiency virus Tat regulatory protein is essential for virus replication and for the efficient transcription of HIV-1 provirus, and in the pathogenesis of AIDS. The role of the tat gene was investigated in 300 samples. It was found that 71.7% were subtype CRF_01AE, 9.3% were subtype B, while 11.7 and 7.3% of them were cross-reactive and non-typeable, respectively. Moreover the results from peptide ELISA also showed that a low CD4 cell count was related to a low anti-Tat antibody (p < 0.05), which may be due to the progression of HIV-1, which can be found predominantly in AIDS patients. The results of nested PCR showed that the second Tat exon might also play a role in T-cell activation. Reverse transcription polymerase chain reaction (RT-PCR) was used to measure HIV-1 mRNA expression in PBMC. RT-PCR negative results were found mostly in the asymptomatic HIV-seropositive group (88%). HIV-1 mRNA expression was found to correlate with current immunologic status. The differences in Tat protein sequences from DNA sequencing between the patients who had anti-Tat antibody positive and anti-Tat antibody negative, were not significant (p > 0.05). These results suggested that the Tat amino acid sequences were conserved among each group of samples and did not change significantly compared with the consensus sequence in previous studies. Several factors make Tat an attractive target for vaccine design.

Papel de los macrófagos en la persistencia de la infección por HIV / Paper of the macrophages in the persistent HIV infection

Luego del tratamiento anti-retroviral combinado de alta eficacia, la mayoría de los pacientes HIV+ recuperan los niveles de linfocitos T CD4+ y reducen la carga viral plasmática, a veces a niveles inferiores a los detectables con métodos de gran sensibilidad. Sin embargo, al interrumpir el tratamiento, los valores de CD4 caen, los niveles de carga viral retornan a los observados antes del tratamiento y no se conoce la fuente del virus re-emergente. Por un lado se reconoce la existencia de reservorios de virus latente en células CD4 de memoria en reposo. Además se ha demostrado la replicación continua de HIV, en tejidos en los cuales la concentración de los antiretrovirales es subóptima. Se presenta un sistema de cultivo prolongado sin estímulo de los leucocitos mononucleares de sangre periférica que puede ser útil para detectar el "pool" de células con replicación residual. Mediante este sistema se demostró que es posible recuperar virus infectivo a partir de los monocitos de sangre periférica de pacientes HIV+ que han recibido hasta 3 años de tratamiento anti-retroviral combinado no interrumpido. Los niveles de este reservorio caen después de tiempos más prolongados de tratamiento, lo que sugiere que es posible reducir esta fuente de virus re-emergente.

Actualidades en el tratamiento de la infección por el virus de la inmunodeficiencia humana (VIH) / Update on the treatment of human immunodeficiency virus infection (HIV)

El síndrome de inmunodeficiencia adquirida fue descrito desde 1981. El primer medicamento con efecto antirretroviral aprobado fue la zidovudina en 1987. Desde entonces han surgido una gran cantidad de nuevos medicamentos y combinaciones de éstos para intentar la curación o, al menos, el control de la progresión de esta terrible infección. Existen nuevas formas de monitorizar la evolución y respuesta al tratamiento que han permitido establecer esquemas de tratamiento específicos para cada caso. La meta en el tratamiento de la infección por virus de la inmunodeficiencia humana es lograr la supresión de la replicación viral. En este artículo se revisan las nuevas opciones de tratamiento y seguimiento del paciente con infección por el virus de la inmunodeficiencia humana

Biologia Molecular del virus dengue / Molecular biology of dengue virus

En Venezuela el problema del Dengue se há agudizado en la última década, siendo en estos momentos el país, una región hiperendémica, donde circulan tres de los cuatro serotipos del virus simultáneamente. Esto convierte al Dengue en un problema de salud pública, por lo que el conocimiento del virus en lo que se refiere a su ciclo de vida, sus características y todo lo relacionado com su biología es de vital importancia para combatirlo y para el desarrollo de una vacuna efectiva. En el presente trabajo se discute de manera general, diferentes aspectos relacionados com la biología molecular del virus Dengue y su ciclo de vida; su estructura y composición, la producción de las proteínas virales tanto estructurales como las no estructurales, las cuales participan en el ciclo de replicación. También se mencionan algunos aspectos relacionados con el ensamblaje y salida del virus de la célula. Con esto se espera dar una visión general de la biología molecular del Dengue y su replicación dentro de la célula huésped.