Epidemiology and molecular characterization of hepatitis B virus in Luanda, Angola

An estimated 360 million people are infected with hepatitis B virus (HBV) worldwide. Among these, 65 million live in Africa. Despite the high levels of hepatitis B in Africa, HBV epidemiology is still poorly documented in most African countries. In this work, the epidemiological and molecular characteristics of HBV infection were evaluated among the staff, visitors and adult patients (n = 508) of a public hospital in Luanda, Angola. The overall prevalence of hepatitis B core antibody (anti-HBc) and hepatitis B surface antigen was 79.7% and 15.1%, respectively. HBV infection was higher in males and was more prevalent in individuals younger than 50 years old. HBV-DNA was detected in 100% of HBV "e" antigen-positive serum samples and in 49% of anti-hepatitis Be antibody-positive samples. Thirty-five out of the 40 HBV genotypes belonged to genotype E. Circulation of genotypes A (4 samples) and D (1 sample) was also observed. The present study demonstrates that HBV infection is endemic in Luanda, which has a predominance of genotype E. This genotype is only sporadically found outside of Africa and is thought to have emerged in Africa at a time when the trans-Atlantic slave trade had stopped.

Soluble inflammatory markers as predictors of virological response in patients with chronic hepatitis C virus infection treated with interferon-α plus ribavirin

The host immune response plays an important role in viral clearance in patients who are chronically infected with hepatitis C virus (HCV) and are treated with interferon and ribavirin. Activation of the immune system involves the release of pro and anti-inflammatory molecules that can be measured in plasma samples. The present study aimed to evaluate the association between pretreatment plasma levels of chemokines and soluble tumor necrosis factor receptors (sTNF-R) and the virological response in treated patients with chronic hepatitis C infection. Forty-one chronically-infected HCV patients that were being treated with interferon-α (IFN-α) plus ribavirin were included in the study. Socio-demographic, clinical and laboratory data were collected and pretreatment plasma levels of chemokine CCL2, CCL3, CCL11, CCL24, chemokine CXCL9, CXCL10, sTNF-R1 and sTNF-R2 were measured. The virological response was assessed at treatment week 12, at the end of treatment and 24 weeks after treatment. Pretreatment CXCL10 levels were significantly higher in patients without an early virological response (EVR) or sustained virological response (SVR) compared to responders [512.9 pg/mL vs. 179.1 pg/mL (p = 0.011) and 289.9 pg/mL vs. 142.7 pg/mL (p = 0.045), respectively]. The accuracy of CXCL10 as a predictor of the absence of EVR and SVR was 0.79 [confidence interval (CI) 95%: 0.59-0.99] and 0.69 (CI 95%: 0.51-0.87), respectively. Pretreatment plasma levels of the other soluble inflammatory markers evaluated were not associated with a treatment response. Pretreatment CXCL10 levels were predictive of both EVR and SVR to IFN-α and ribavirin and may be useful in the evaluation of candidates for therapy.

Genetic and biological characterization of a densovirus isolate that affects dengue virus infection

Brevidensoviruses have an encapsidated, single-stranded DNA genome that predominantly has a negative polarity. In recent years, they have received particular attention due to their potential role in the biological control of pathogenic arboviruses and to their unnoticed presence in cell cultures as contaminants. In addition, brevidensoviruses may also be useful as viral vectors. This study describes the first genetic and biological characterization of a mosquito densovirus that was isolated in Brazil; moreover, we examined the phylogenetic relationship between this isolate and the other brevidensoviruses. We further demonstrate that this densovirus has the potential to be used to biologically control dengue virus (DENV) infection with in vitro co-infection experiments. The present study provides evidence that this densovirus isolate is a fast-spreading virus that affects cell growth and DENV infection.

Neutralising antibodies for West Nile virus in horses from Brazilian Pantanal

Despite evidence of West Nile virus (WNV) activity in Colombia, Venezuela and Argentina, this virus has not been reported in most South American countries. In February 2009, we commenced an investigation for WNV in mosquitoes, horses and caimans from the Pantanal, Central-West Brazil. The sera of 168 horses and 30 caimans were initially tested using a flaviviruses-specific epitope-blocking enzyme-linked immunosorbent assay (blocking ELISA) for the detection of flavivirus-reactive antibodies. The seropositive samples were further tested using a plaque-reduction neutralisation test (PRNT90) for WNV and its most closely-related flaviviruses that circulate in Brazil to confirm the detection of specific virus-neutralising antibodies. Of the 93 (55.4%) blocking ELISA-seropositive horse serum samples, five (3%) were seropositive for WNV, nine (5.4%) were seropositive for St. Louis encephalitis virus, 18 (10.7%) were seropositive for Ilheus virus, three (1.8%) were seropositive for Cacipacore virus and none were seropositive for Rocio virus using PRNT90, with a criteria of > four-fold antibody titre difference. All caimans were negative for flaviviruses-specific antibodies using the blocking ELISA. No virus genome was detected from caiman blood or mosquito samples. The present study is the first report of confirmed serological evidence of WNV activity in Brazil.

Full-length genomic sequence of hepatitis B virus genotype C2 isolated from a native Brazilian patient

The hepatitis B virus (HBV) is among the leading causes of chronic hepatitis, cirrhosis and hepatocellular carcinoma. In Brazil, genotype A is the most frequent, followed by genotypes D and F. Genotypes B and C are found in Brazil exclusively among Asian patients and their descendants. The aim of this study was to sequence the entire HBV genome of a Caucasian patient infected with HBV/C2 and to infer the origin of the virus based on sequencing analysis. The sequence of this Brazilian isolate was grouped with four other sequences described in China. The sequence of this patient is the first complete genome of HBV/C2 reported in Brazil.

Sequence analysis of the 2009 pandemic influenza A H1N1 virus haemagglutinin gene from 2009-2010 Brazilian clinical samples

In this paper, we analysed the haemagglutinin (HA) gene identified by polymerase chain reaction from 90 influenza A H1N1 virus strains that circulated in Brazil from April 2009-June 2010. A World Health Organization sequencing protocol allowed us to identify amino acid mutations in the HA protein at positions S220T (71%), D239G/N/S (20%), Y247H (4.5%), E252K (3.3%), M274V (2.2%), Q310H (26.7%) and E391K (12%). A fatal outcome was associated with the D239G mutation (p < 0.0001). Brazilian HA genetic diversity, in comparison to a reference strain from California, highlights the role of influenza virus surveillance for study of viral evolution, in addition to monitoring the spread of the virus worldwide.

Prevalence of hepatitis B and C virus infection among leprosy patients in a leprosy-endemic region of central Brazil

Leprosy and hepatitis B virus (HBV) are highly endemic in some regions of the state of Mato Grosso, in central Brazil. The association of leprosy with HBV and hepatitis C virus (HCV) was assessed using a seroprevalence study and 191 leprosy outpatients were included. Demographic data and the clinical classification of leprosy were recorded. Evidence of previous HBV infection was present in 53 patients (27.7%, 95% confidence interval: 21.9-34.5) and two (1%) were HBsAg positive. Five (2.6%) had antibodies to HCV. The prevalence of previous exposure to HBV was higher than expected for an adult population in central Brazil. In contrast, the prevalence of anti-HCV antibodies was not much higher regarding the age range of participants. HBV markers were associated with a higher number of sex partners and the use of injections without proper sterilisation of the syringes. The number of HBV carriers was small, suggesting that there was no increased likelihood of chronification among these patients.

Influence of GB virus C on IFN-γ and IL-2 production and CD38 expression in T lymphocytes from chronically HIV-infected and HIV-HCV-co-infected patients

This study was designed to assess the effect of GB virus (GBV)-C on the immune response to human immunodeficiency virus (HIV) in chronically HIV-infected and HIV- hepatitis C virus (HCV)-co-infected patients undergoing antiretroviral therapy. A cohort of 159 HIV-seropositive patients, of whom 52 were HCV-co-infected, was included. Epidemiological data were collected and virological and immunological markers, including the production of interferon gamma (IFN-γ) and interleukin (IL)-2 by CD4, CD8 and Tγδ cells and the expression of the activation marker, CD38, were assessed. A total of 65 patients (40.8%) presented markers of GBV-C infection. The presence of GBV-C did not influence HIV and HCV replication or TCD4 and TCD8 cell counts. Immune responses, defined by IFN-γ and IL-2 production and CD38 expression did not differ among the groups. Our results suggest that neither GBV-C viremia nor the presence of E2 antibodies influence HIV and HCV viral replication or CD4 T cell counts in chronically infected patients. Furthermore, GBV-C did not influence cytokine production or CD38-driven immune activation among these patients. Although our results do not exclude a protective effect of GBV-C in early HIV disease, they demonstrate that this effect may not be present in chronically infected patients, who represent the majority of patients in outpatient clinics.

Potential impact of a presumed increase in the biting activity of dengue-virus-infected Aedes aegypti (Diptera: Culicidae) females on virus transmission dynamics

Recently, we showed that infection with dengue virus increases the locomotor activity of Aedes aegypti females. We speculate that the observed increased locomotor activity could potentially increase the chances of finding a suitable host and, as a consequence, the relative biting rate of infected mosquitoes. We used a mathematical model to investigate the impact of the increased locomotor activity by assuming that this activity translated into an increased biting rate for infected mosquitoes. The results show that the increased biting rate resulted in dengue outbreaks with greater numbers of primary and secondary infections and with more severe biennial epidemics.

Can thymic epithelial cells be infected by human T-lymphotropic virus type 1?

The human T-lymphotropic virus type-1 (HTLV-1) is the cause of adult T cell leukaemias/lymphoma. Because thymic epithelial cells (TEC) express recently defined receptors for the virus, it seemed conceivable that these cells might be a target for HTLV-1 infection. We developed an in vitro co-culture system comprising HTLV-1+-infected T cells and human TECs. Infected T cells did adhere to TECs and, after 24 h, the viral proteins gp46 and p19 were observed in TECs. After incubating TECs with culture supernatants from HTLV-1+-infected T cells, we detected gp46 on TEC membranes and the HTLV-1 tax gene integrated in the TEC genome. In conclusion, the human thymic epithelium can be infected in vitro by HTLV-1, not only via cell-cell contact, but also via exposure to virus-containing medium.

Chikungunya virus outbreak in Kerala, India, 2007: a seroprevalence study

India was affected by a major outbreak of chikungunya fever caused by Chikungunya virus (CHIKV) during 2006-2007. Kerala was the worst affected state during 2007 with a contribution of 55.8% suspected cases in the country. However, except for clinically reported case records, no systematic information is available on infection status of CHIKV in the region. Hence, we carried out a post-epidemic survey to estimate seroprevalence status [immunoglobulin G (IgG)] in the community using commercially available indirect immunofluorescence test. This methodology had been reported to be highly specific and sensitive for CHIKV infection. The study area selected was the worst affected mid-highlands region of Kerala which harbour vast area of rubber plantations. The study evidenced 68% of the population to be seropositive for CHIKV IgG. Males were found more affected than females (χ2 = 9.86; p = 0.002). Among males, prevalence was significantly higher in the age classes 21-30 (χ2 = 5.46; p = 0.019) and 31-40 (χ2 = 5.84; p = 0.016) years. This may be due to high occupational risk of the male population engaged in plantation activities exposed to infective bites of Aedes albopictus. The current study provides an insight into the magnitude of CHIKV outbreak in Kerala.

Association of hepatitis C virus NS5B variants with resistance to new antiviral drugs among untreated patients

Mutations located in the 109-amino acid fragment of NS5B are typically associated with resistance to interferon (IFN) and ribavirin (RIB) and to new antiviral drugs. The prevalence of these mutations was examined in 69 drug-naïve individuals with hepatitis C virus (HCV) infections in Rio de Janeiro, Brazil. Mutations related to non-response to IFN/RIB were observed in all subtypes studied (1a, 1b, 2b, 3a and 4). The most common mutation was Q309R, present in all subtypes, except subtype 2b with frequency above 20%. D244N was detected only in subtype 3a and A333E was detected only in subtype 2b. We did not detect the S282T, S326G or T329I mutations in any of the samples analysed. Of note, the C316N mutation, previously related to a new non-nucleoside compound (HCV796 and AG-021541), was observed in only eight of 33 (24%) samples from subtype 1b. Site 316 was under positive selection in this HCV variant. Our data highlight the presence of previously described resistance mutations in HCV genotypes from drug-naïve patients.

The depuration dynamics of oysters (Crassostrea gigas) artificially contaminated with hepatitis A virus and human adenovirus

Within the country of Brazil, Santa Catarina is a major shellfish producer. Detection of viral contamination is an important step to ensure production quality and consumer safety during this process. In this study, we used a depuration system and ultraviolet (UV) disinfection to eliminate viral pathogens from artificially infected oysters and analysed the results. Specifically, the oysters were contaminated with hepatitis A virus (HAV) or human adenovirus type 5 (HAdV5). After viral infection, the oysters were placed into a depuration tank and harvested after 48, 72 and 96 h. After sampling, various oyster tissues were dissected and homogenised and the viruses were eluted with alkaline conditions and precipitated with polyethylene glycol. The oyster samples were evaluated by cell culture methods, as well as polymerase chain reaction (PCR) and quantitative-PCR. Moreover, at the end of the depuration period, the disinfected seawater was collected and analysed by PCR. The molecular assays showed that the HAdV5 genome was present in all of the depuration time samples, while the HAV genome was undetectable after 72 h of depuration. However, viral viability tests (integrated cell culture-PCR and immunofluorescence assay) indicated that both viruses were inactivated with 96 h of seawater recirculation. In conclusion, after 96 h of UV treatment, the depuration system studied in this work purified oysters that were artificially contaminated with HAdV5 and HAV.

Prevalence of human papillomavirus and Epstein-Barr virus DNA in penile cancer cases from Brazil

Penile cancer is a potentially mutilating disease. Although its occurrence is relatively rare worldwide, penile cancer rates can be high in developing countries. A few studies have been conducted on the involvement of human papillomavirus (HPV) in penile carcinoma, which have found HPV present in 30-70% of penile malignant lesions, with a higher prevalence of HPV 16 and 18. It has been assumed that cofactors, such as Epstein-Barr virus (EBV) infections, may play a role in the progression of penile neoplasia. The aim of this study was to determine HPV and EBV prevalence in 135 penile malignant lesions from Brazilian men through the use of MY09/11 polymerase chain reaction (PCR), type-specific PCR and restriction fragment length polymorphism analysis. HPV prevalence among the men tested was 60.7%. Of the men who tested positive, 27 presented with HPV 16 (29.7%), five with HPV 18 (5.5%), 21 with HPV 45 (23.1%) and nine with HPV 6 (9.9%). Seven mixed infections were detected (9.2%), while 11 cases remained untyped (13.4%). Regarding EBV positivity, 46.7% of the samples contained EBV DNA with EBV-1 as the most prevalent type (74.6%). More than 23% of the men were co-infected with both HPV and EBV, while 35% presented exclusively with HPV DNA and 20% presented only with EBV DNA. Penile carcinoma aetiology has not been fully elucidated and the role of HPV and EBV infections individually or synergistically is still controversial. Hence, more studies are needed to determine their possible role in carcinogenesis.