Roberta Sitnik

Hepatitis B Virus Genotypes and Precore and Core Mutants in Brazilian Patients

ABSTRACT A method for genotyping hepatitis B virus by partial HBsAg gene sequencing with primers common to all known genotypes was developed. Mutations related to anti-HBs resistance are also detected with this method. Samples from 103 Brazilian patients were analyzed. Precore and core region of these viruses were also sequenced in 101 patients. Genotypes A, B, C, D, and F were found with frequencies of 49.5, 2.9, 13.6, 24.3, and 9.7%, respectively. Genotypes B and C were found only in Asian patients, whereas genotypes A, D, and F were more common in patients without an Asian background. Precore mutants were found in 32 (31.7%) of 101 patients, with a higher frequency in those infected with genotype D (22 of 25 [88.0%]). Analysis of nucleotide 1858 showed presence of thymine in all patients with genotypes B, C, and D and in a few patients with genotypes A (10.0%) and F (30.0%), who showed more frequently the presence of cytosine. This nucleotide was closely related to the presence of precore mutants. Mutations in the basal core promoter were found in 64 of 101 (63.4%) samples. These mutations were more frequent in patients infected with genotype F (90.0%) and less frequent in patients infected with genotype B (33.3%). Deletions in this region were found in two genotype C-infected patients.

Properties of the digestive enzymes and the permeability of the peritrophic membrane of Spodoptera frugiperda (Lepidoptera) larvae

Abstract The physical and kinetic properties of several soluble and detergent-solubilized membrane-bound midgut hydrolases of Spodoptera frugiperda (Lepidoptera) were investigated. The following techniques were employed: isoelectric focusing and electrophoresis in polyacrylamide gels, density-gradient ultracentrifugation and gel filtration in Superose columns. In vivo molecular weights of the hydrolases were considered to correspond with those determined by centrifugation, which is the more gentle of the procedures employed. Using this criterion, the soluble hydrolases display the following number of sub-units: acetylglucosaminidase [pHo5 (pH optimum), Mr 123,000], 2; aminopeptidase (pHo 7.4, Mr 107,000), 2; amylase (pHo9.6, Km for starch 0.38%, Mr 87,000), 1; carboxypeptidase A (pHo 8.0, Mr 45,000), 2; cellobiase (pHo 7.0, Mr 124,000), 2; dipeptidase (pHo 8.0, Mr 95,000), 2; maltase (pHo 5.0, Mr 150,000), 2; trypsin (pHo 7.9, Mr 51,000), 2. Amylase is not activated by chloride. A comparison between the diameters of the enzymes which pass through the peritrophic membrane (amylase, carboxypeptidase and trypsin) with that which is secreted into the lumen but do not pass through the peritrophic membrane (acetylglucosaminase) suggests that the pores of S. frugiperda larval peritrophic membrane have diameters of 7.5–8 nm.

A real-time quantitative assay for hepatitis B DNA virus (HBV) developed to detect all HBV genotypes

Hepatitis B virus (HBV) is a major cause of chronic liver disease worldwide. Besides genotype, quantitative analysis of HBV infection is extensively used for monitoring disease progression and treatment. Affordable viral load monitoring is desirable in resource-limited settings and it has been already shown to be useful in developing countries for other viruses such as Hepatitis C virus (HCV) and HIV. In this paper, we describe the validation of a real-time PCR assay for HBV DNA quantification with TaqMan chemistry and MGB probes. Primers and probes were designed using an alignment of sequences from all HBV genotypes in order to equally amplify all of them. The assay is internally controlled and was standardized with an international HBV panel. Its efficacy was evaluated comparing the results with two other methods: Versant HBV DNA Assay 3.0 (bDNA, Siemens, NY, USA) and another real-time PCR from a reference laboratory. Intra-assay and inter-assay reproducibilities were determined and the mean of CV values obtained were 0.12 and 0.09, respectively. The assay was validated with a broad dynamic range and is efficient for amplifying all HBV genotypes, providing a good option to quantify HBV DNA as a routine procedure, with a cheap and reliable protocol.

Hepatitis B virus genotypes from European origin explains the high endemicity found in some areas from southern Brazil

Southern Brazil is considered an area of low Hepatitis B endemicity, but some areas of higher endemicity have been described in the Southwest of Paraná and Santa Catarina states. The aim of this study was to evaluate viral genotypes circulating throughout Paraná state. PCR amplification and partial sequencing of the S gene was carried out in 228 samples from HBsAg positive candidate blood donors. Samples have been collected in seven different counties (Cascavel, Curitiba, Foz do Iguaçu, Francisco Beltrão, Maringá, Londrina and Paranaguá). The most common HBV genotype in Paraná state was D (82.9%; 189/228), followed by A (14.1%; 32/228). Genotypes F (1.3%; 3/228), C (1.3%; 3/228) and H (0.4%; 1/228) were also found. Distribution of genotypes was different in the studied counties, but genotype D was the most frequent in all of them. In Francisco Beltrão, all studied samples belonged to genotype D. The high prevalence of HBV genotype D in South of Brazil is explained by the intense migration of settlers from Europeans countries. Subgenotypes A1 and A2 were identified circulating in all cities where HBV/A was found. As observed in other areas of Brazil, HBV/A1 is more frequent than the HBV/A2 in Paraná state and its presence was significantly larger in black and mulatto individuals. Genotype C was found only in individuals with Asian ancestry from Londrina and Maringá. Most HBV/F sequences identified in this study were classified as subgenotype F2a that was previously described in Brazil. The sole case of subgenotype F4 was from Foz do Iguaçu city, near to Northern Argentina, where F4 is highly prevalent. The single genotype H sample was from Curitiba. This is the first case of this genotype described in Brazil. Further studies should be carried out to determine if more genotype H samples can be found in other populations from Brazil.

Predictive factors for response to Lamivudine in chronic hepatitis B

BACKGROUND Lamivudine has been shown to be an efficient drug for chronic hepatitis B (CHB) treatment. AIM To investigate predictive factors of response, using a quantitative method with high sensitivity. METHODS We carried out a prospective trial of lamivudine in 35 patients with CHB and evidence for viral replication, regardless to their HBeAg status. Lamivudine was given for 12 months at 300 mg daily and 150 mg thereafter. Response was considered when DNA was undetectable by PCR after 6 months of treatment. Viral replication was monitored by end-point dilution PCR. Mutation associated with resistance to lamivudine was detected by DNA sequencing in non-responder patients. RESULTS Response was observed in 23/35 patients (65.7%) but only in 5/15 (33.3%) HBeAg positive patients. Only three pre-treatment variables were associated to low response: HBeAg (p = 0.006), high viral load (DNA-VHB > 3 x 10(6) copies/ml) (p = 0.004) and liver HBcAg (p = 0. 0028). YMDD mutations were detected in 7/11 non-responder patients. CONCLUSIONS HBeAg positive patients with high viral load show a high risk for developing drug resistance. On the other hand, HBeAg negative patients show a good response to lamivudine even with high viremia.

Efficacy and tolerability of long-term therapy using high lamivudine doses for the treatment of chronic hepatitis B

Purpose. A long-term follow-up study was carried out to evaluate the tolerability and efficacy of long-term therapy (1 to 3 years) with high doses (150 or 300 mg daily) of lamivudine for chronic hepatitis B. Methods. Thirty-two patients were studied, including those who were seronegative for hepatitis B e antigen (HBeAg), as well as those with decompensated liver cirrhosis. Viral DNA clearance was monitored by using end-point dilution polymerase chain reaction (PCR), a highly sensitive method. Hepatitis B virus (HBV) polymerase gene mutations associated with resistance were determined by sequencing. Results. Response to lamivudine in the sixth month was observed in 19/32 (59.4%) patients. With one exception, viral DNA results observed at this time were maintained. The YMDD mutation was detected in 12 nonresponder patients (9 YVDD, 2 YIDD, and 1 mixed population Y(V/I)DD), generally associated with the L528M mutation. Re-takeover by the wild type was observed 6 to 18 months after lamivudine withdrawal. Lamivudine response rates in noncirrhotic and cirrhotic patients were 9/18 (50%) and 10/14 (71.4%), respectively. HBeAg to anti-HBe seroconversion was found after different periods in all responder patients. Hepatitis B surface antigen (HBsAg) clearance and anti-HBs seroconversion were occasionally found. Conclusions. In nonresponder patients, resistant mutants appeared up to the second year of lamivudine therapy. In spite of the presence of resistant mutants, maintenance of therapy was usually associated with a lower viral load. In responder patients, maintenance of therapy was associated with continued absence of detectable HBV DNA in serum, as monitored by highly sensitive methods. No significant side effects caused by lamivudine were observed in our patients, even in those with liver cirrhosis.

Novel point mutations in the dystrophin gene

Duchenne (DMD) and Becker (BMD) type muscular dystrophies are allelic X‐linked recessive disorders caused by mutations in the gene encoding dystrophin. About 65% of the cases are caused by deletions, while 5–10% are duplications. The remaining 30% of affected individuals may have smaller mutations (point mutations or small deletions/insertions) which cannot be identified by current diagnostic screening strategies. In order to look for pathogenic small mutations in the dystrophin gene, we have screened the 18 exons located in the hot spot region of this gene through two different single strand conformation polymorphism (SSCP) conditions. Five different pathogenic mutations were identified in 6 out of 192 DMD/BMD patients without detectable deletions: 2 nonsense, 1 bp insertion, 1 bp deletion and 1 intronic. Except for the intronic change, which alters a splice site, all the others cause a premature stop codon. In addition, 8 apparently neutral changes were identified. However, interestingly, one of them was not identified in 195 normal chromosomes, although it was previously described in a DMD patient from a different population. The possibility that this mutation may be pathogenic is discussed. Except for two neutral changes, all the others are apparently here described for the first time. Hum Mutat 10:217–222, 1997.

Association with Spontaneous Hepatitis C Viral Clearance and Genetic Differentiation of IL28B/IFNL4 Haplotypes in Populations from Mexico

Aim To analyze the genetic heterogeneity of the Amerindian and admixed population (Mestizos) based on the IL28B (rs12979860, rs8099917) and IFNL4 (rs368234815) haplotypes, and their association with spontaneous clearance (SC) and liver damage in patients with hepatitis C infection from West Mexico. Methods A total of 711 subjects from West Mexico (181 Amerindians and 530 Mestizos) were studied for the prevalence of IL28B (rs12979860C/T, rs8099917G/T) and IFNL4 (rs368234815∆G/TT) genotypes. A case-control study was performed in 234 treatment-naïve HCV Mestizos (149 chronic hepatitis C and 85 with SC) for the association of haplotypes with SC and liver damage. A real-time PCR assay was used for genotyping, and transitional elastography staged liver damage. Results Significant Fst-values indicated differentiation between the studied populations. The frequencies of the protective C, T, TT alleles were significantly lower in the Amerindians than in Mestizos (p<0.05). The r2 measure of linkage disequilibrium was significant for all variants and the T/G/ΔG risk haplotype predominated in Amerindians and secondly in Mestizos. The protective C/T/TT haplotype was associated with SC (OR = 0.46, 95% IC 0.22–0.95, p = 0.03) and less liver damage (OR = 0.32, 95% IC 0.10–0.97, p = 0.04) in chronic patients. The Structure software analysis demonstrated no significant differences in ancestry among SC and chronic patients. Conclusions West Mexico´s population is genetically heterogeneous at the IL28B/IFNL4 polymorphisms. The T/G/ΔG high-risk haplotype predominated in Amerindians and the beneficial alternative haplotype in Mestizos. The C/T/TT haplotype was associated with SC and less liver damage in chronically infected Mestizo patients.

SeptiFast for diagnosis of sepsis in severely ill patients from a Brazilian hospital

ABSTRACT Objective To test and validate a multiplex real-time polymerase chain reaction method for bloodstream infections, as well as to compare the results with conventional blood culture. Methods A total of 114 consecutive patients with clinical evidence of sepsis were submitted to blood culture and LightCycler™ SeptiFast tests. Results More positive specimens (23; 20.2%) were detected using the LightCycler™ SeptiFast than the blood culture (17; 14.9%), with an agreement of 86.8%. Discordant results were seen in four patients positive only to blood culture, ten positive only to LightCycler™ SeptiFast and one to different pathogens found by each test. Infections with microorganisms detected only using blood culture reassured the need to perform both tests. The mean time to results for blood culture was 5 days for negative and 3.5 days for positive results. LightCycler™ SeptiFast results were achieved in less than 8 hours. Conclusion LightCycler™ SeptiFast showed a high potential as a test to be carried out concomitantly with blood culture for sepsis diagnosis in severely ill patients. This test allowed a faster diagnosis of bacterial and fungal infections that helped to reduce hospital stay and to control the use of antibiotics. LightCycler™ SeptiFast can also eventually detect microorganism and infections that are hardly detected by blood culture, especially Candida non-albicans infections.

Real-time PCR in infectious uveitis as an alternative diagnosis

PURPOSE Uveitis is a major visual impairment disease affecting parts or the entire uveal tract and occasionally the sclera, the cornea or the optic nerve. The disease is a major cause of ocular morbidity and blindness in immunocompetent and immunocompromised patients. In this work we analyzed the sensitivity and specificity of real-time PCR to detect the etiological agent from blood, plasma, vitreous and aqueous humor and compared with the diagnostic hypothesis. METHODS Twenty-seven patients (13 male) were studied and Real-time PCR method was used for the detection of herpes simplex virus 1 (HSV-1), herpes simplex virus 2 (HSV-2), varicella zoster virus (VZV), cytomegalovirus (CMV), Mycobacterium tuberculosis (TB) and Toxoplasma gondii (Toxo) in the aqueous humor as well as in the vitreous, blood and plasma. RESULTS Our results showed the presence of Toxo, CMV, VZV or HSV-2 in 19.2% of aqueous humor samples, and in 30% of vitreous humor samples. In plasma and blood samples, only CMV was detected (11.1% and 3.7%, respectively). CONCLUSION Real-time PCR was able to detect and to confirm diagnostic hypothesis in uveitis. Our data also confirms that vitreous humor is the best source for molecular diagnosis of infectious uveitis but indicates aqueous humor samples that are easier to obtain may also be appropriate to be tested by Real-time PCR.