HCMV UL97 phosphotransferase gene mutations may be associated with antiviral resistance in immunocompromised patients in Belém, PA, Northern Brazil

Abstract INTRODUCTION: Human cytomegalovirus is one of the causes of opportunist infections in immunocompromised patients, and is triggered by factors such as state of viral latency, weakened immune responses, and development of antiviral resistance to ganciclovir, the only drug offered by the public health system in Brazil to treat the infection. The goal of this study was to identify mutations that may be associated with antiviral resistance in immunocompromised patients. METHODS: Molecular analysis was performed in 82 blood samples and subjected to genomic DNA extraction by a silica-based method. Three sequences of the HCMV UL97 gene, which encodes a phosphotransferase protein required for activation of ganciclovir, were amplified by polymerase chain reaction. Pyrosequencing methods were applied to one external 2096-bp segment DNA and two internal sequences between nucleotides 1087 to 1828 to detect mutations in this gene. RESULTS: Approximately 10% of sequences contained mutations between nucleotides 377 and 594, in conserved regions of the UL97 gene, leading to amino acid changes. Eleven coding mutations were identified, including changes leading to amino acid substitutions, E596K and S604F, which were observed in 100% of samples and are described for the first time in Brazil. In addition, one mutation (A594V) that is associated with ganciclovir resistance was detected in a kidney transplant patient. CONCLUSIONS: Further studies to detect mutations associated with HCMV resistance to antiviral drugs are required to demonstrate the need to increase the variety and availability of drugs used to treat viral infections in the public health care system in Brazil.

Reporte de caso de resistencia al ganciclovir en enfermedad por citomegalovirus postrasplante cardiaco: case report / Resistance to ganciclovir in cytomegalovirus infection after heart transplant

La infección por citomegalovirus postrasplante cardiaco es una condición médica recurrente. Su frecuencia se incrementa cuando los donantes poseen serología positiva y los receptores presentan serología negativa para el virus. En la población pediátrica, la enfermedad solo se desarrolla en un porcentaje pequeño y raramente presentan resistencia al tratamiento convencional con ganciclovir y valganciclovir. Presentamos el primer reporte de caso pediátrico de enfermedad por citomegalovirus resistente a ganciclovir y valganciclovir postrasplante cardiaco en un hospital público peruano, con una presentación inusual. La resistencia a estos fármacos fue evidente luego de 277 días de evolución de la enfermedad, ante la no remisión de la sintomatología y la persistencia de una carga viral elevada. La posterior administración de foscarnet condujo a una mejora clínica y de laboratorio, hasta la remisión de la enfermedad.

Cytomegalovirus infection after a heart transplant is a recurrent medical condition. Its frequency increases when the donors are serum-positive, and the recipients are serum-negative to this virus. In the pediatric population, the infection only develops in a small percentage and the patients rarely present resistance to conventional treatment with ganciclovir and valganciclovir. We presented the first report of a pediatric case of the cytomegalovirus infection resistant to ganciclovir and valganciclovir after a heart transplant in a Peruvian public hospital with an unusual presentation. The resistance to these drugs was evident after 277 days of evolution of the disease considering the non-remission of the symptomatology and the persistence of an elevated viral load. The administration of foscarnet led to a clinical and laboratory improvement until remission of the disease.

Research of hepatitis B virus genotyping and pre-existing antiviral resistance mutation in Shenzhen area / 国际检验医学杂志

Objective To understand the hepatitis B virus(HBV)genotyping and pre-existing antiviral resistance mutation in the patients with clinical chronic HBV infection in Shenzhen area.Methods Serum samples in 244 cases of chronic HBV infection were detected for HBV genotyping and pre-existing antiviral resistance mutation by using PCR combined with reverse dot hybridization. Results In 244 cases of chronic HBV infection,3 kinds of genotype were found,including 143 cases(58.6%)of genotype B,100 ca-ses(41%)of genotype C and 1 case(0.4%)of genotype D;38 cases(15.57%)of pre-existing antiviral resistance mutation were de-tected out.The total detection rate of pre-existing antiviral resistance mutation was 15.57%,in which 22 cases(9.01%)were related with lamivudine resistance and 16 cases(6.56%)were related with adefovir dipivoxil resistance.Conclusion The genotype B and C are the main genotypes in Shenzhen area,and the incidence rate of pre-existing antiviral resistance mutation in the patients with chronic HBV infection is relatively high.The detection of genotyping and pre-existing antiviral resistance mutation of HBV has the important significance to predict the disease progression and guide the individulized treatment.

Options for the management of antiviral resistance during hepatitis B therapy: reflections on battles over a decade

Although much advancement has been achieved in the treatment of chronic hepatitis B, antiviral resistance is still a challenging issue. Previous generation antiviral agents have already developed resistance in a number of patients, and it is still being used especially in resource limited countries. Once antiviral resistance occurs, it predisposes to subsequent resistance, resulting in multidrug resistance. Therefore, prevention of initial antiviral resistance is the most important strategy, and appropriate choice and modification of therapy would be the cornerstone in avoiding treatment failures. Until now, management of antiviral resistance has been evolving from sequential therapy to combination therapy. In the era of tenofovir, the paradigm shifts again, and we have to decide when to switch and when to combine on the basis of newly emerging clinical data. We expect future eradication of chronic hepatitis B virus infection by proper prevention and optimal management of antiviral resistance.

The mechanism and treatment of anti-viral resistant hepatitis B virus / 대한내과학회지

Even though substantial advances have been made in the treatment of chronic hepatitis B in the past decade with the use of oral nucleos(t)ide analogues (NAs), emergence of anti-viral resistance is the most important factor in treatment failure for chronic hepatitis B. Therefore, prevention and management of antiviral resistant HBV is major challenge in the era of oral NAs therapy. Recently, several guidelines for the management of antiviral resistant HBV have been published. Herein, I will discuss how to prevent and manage antiviral resistance.

A Case of Oseltamivir-Resistant Pandemic Influenza (H1N1 2009) in a Patient with Acute Myeloid Leukemia / 감염과화학요법

Oseltamivir is the drug of choice for patients with pandemic influenza (H1N1 2009). However, sporadic cases of oseltamivir resistance have been described worldwide. Up to March 2010, a total of 11 strains (2.2% of tested isolates) of oseltamivir-resistant pandemic influenza (H1N1 2009) have been discovered in South Korea. We report a case of 46-year-old man with acute myeloid leukemia in whom an oseltamivir-resistant pandemic (H1N1) 2009 virus was isolated. Despite high dose oseltamivir therapy for 10 days he had persistent symptoms and showed positive results in repeated real-time RT-PCR for pandemic influenza (H1N1 2009) virus from nasopharyngeal specimen. The patient improved eventually after oseltamivir was replaced by zanamivir inhalation.

Modelación molecular y variación estructural de las integrasas de dos retrovirus humanos: HTLV-I y VIH-1 / Molecular modeling and structural variation of two human retrovirus integrases: HTLV-I and HIV-1

Objetivo: Analizar las características moleculares y de variación de secuencias de las integrasas del HTLV-I y del VIH-1 y sus variantes poblacionales. Metodología: Análisis de secuencias y estructuras obtenidas de diferentes bases de datos; para ello se utilizaron programas computacionales de modelación de estructuras proteicas e identificación de sustituciones polimórficas en secuencias de aminoácidos de integrasas del HTLV-I y VIH-1 previamente reportadas. Materiales y métodos: Tanto la integrasa del HTLV-I como la del VIH-1 son proteínas compuestas por 288 residuos de aminoácidos. Se encontró un parecido de estructuras terciarias entre los dominios catalíticos de las IN de VIH-1, ASV y RSV con la del HTLV- I. A partir de 103 secuencias completas de la integrasa del VIH-1 se registraron, en 46 codones, un total de 53 sustituciones que se localizaron en diferentes posiciones de la proteína nativa; las más frecuentes fueron: N27G (32,1%), A265V (30,1%), L101I (31,1%) y T123A (27,0%). Ninguna de las sustituciones más frecuentemente encontradas generó un cambio en el plegamiento nativo de la correspondiente región. Conclusión: La estructura tridimensional del dominio central catalítico de la integrasa condicionaría su actividad y su relación con moléculas potencialmente inhibidoras. Las sustituciones observadas fueron neutrales sin alterar la estructura nativa. Los resultados obtenidos confirman que la integrasa es un nuevo y promisorio blanco para el desarrollo de terapias antirretrovirales más efectivas en el siglo XXI...

Objective: To analyze the molecular characteristics and aminoacid sequence variations of HTLV-I and of HIV-1 integrases and their population variants. Materials and methods: Data mining and analysis of integrase sequences and protein structure data bases by using appropriate software for modelling and search for polymorphic substitutions in HTLV-I and HIV-1 integrase amino acid sequences previously reported. Results: HTLV-I and HIV-1 integrases are proteins of 288 amino acid residues. Structural modeling of tertiary folding of HTLV-I integrase catalytic central domain’s, showed closed structural characteristic with those of HIV-1, ASV and RSV. From 103 full amino acid sequences of HIV-1 integrase, 53 substitutions located in 46 different codons were recorded. The more frequents correspond to N27G (32,1%), L101I (31,1%), A265V (30,1%) and T123A (27,0%). None of these frequent substitutions introduced changes in the folding of HIV-1 native integrase. Conclusion: The tridimensional structure of central catalytic domain would influence the integrase activity and its relationship with potentially inhibitory molecules. Those observed aminoacid substitutions were neutral and do not alter the native protein structure. Our data confirm those previously published, and enable us to propose that IN is a new and promissory target for develop more effective antiviral therapies in the XXI century...

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.

Management of Antiviral-Resistant Chronic Hepatitis B Virus Infection / 대한소화기학회지

Substantial progress has been made in the treatment of chronic hepatitis B during the past decade. Nucleos(t)ide analogues are now widely used due to their convenience, less side effects, and considerable response rates. However, development of antiviral resistance is a major problem being considered as the most important factor for the treatment failure. Viral breakthrough associated with selection of antiviral-resistant hepatitis B virus (HBV) is usually followed by biochemical breakthrough, clinical deterioration, and even progressive liver failure. Therefore, appropriate management of antiviral resistance is critical for improving treatment outcomes. Strategies for the management of antiviral-resistant chronic HBV infection are described herein considering recently published guidelines. Lamivudine/telbivudine resistance can be managed by adding adefovir. Switching to adefovir or entecavir is also a viable option. However, careful follow-up of viral load is mandatory to detect any primary or secondary treatment failure in case of sequential monotherapy. Interferon or peg-interferon therapy can also be considered in case of young patients with compensated liver disease. For adefovir resistance, lamivudine can be added, but adding or switching to entecavir is a more reasonable option. Likewise, adding or switching to adefovir can be considered for entecavir resistance. Adding or switching to tenofovir needs to be considered upon availability. Experiences for clevudine resistance are still lacking, and need to be studied further upon the isolation of clinically resistant strains. To avoid emergence of resistant mutations, antiviral therapy should be initiated after careful balance of risk and benefit, and the most potent antiviral agent with the lowest resistance rate should be selected.