Svetoslav Nanev Slavov

Overview of Zika virus (ZIKV) infection in regards to the Brazilian epidemic

Zika virus (ZIKV), a mosquito-borne flavivirus, belongs to the Flaviviridae family, genus Flavivirus. ZIKV was initially isolated in 1947 from a sentinel monkey in the Zika forest, Uganda. Little clinical importance was attributed to ZIKV, once only few symptomatic cases were reported in some African and Southeast Asiatic countries. This situation changed in 2007, when a large outbreak was registered on the Yap Island, Micronesia, caused by the Asian ZIKV lineage. Between 2013 and 2014, ZIKV spread explosively and caused many outbreaks in different islands of the Southern Pacific Ocean and in 2015 autochthonous transmission was reported in Brazil. Currently, Brazil is the country with the highest number of ZIKV-positive cases in Latin America. Moreover, for the first time after the discovery of ZIKV, the Brazilian scientists are studying the possibility for the virus to cause severe congenital infection related to microcephaly and serious birth defects due to the time-spatial coincidence of the alarming increase of newborns with microcephaly and the Brazilian ZIKV epidemic. The present review summarizes recent information for ZIKV epidemiology, clinical picture, transmission, diagnosis and the consequences of this emerging virus in Brazil.

Human parvovirus B19: general considerations and impact on patients with sickle-cell disease and thalassemia and on blood transfusions.

Human parvovirus B19 (B19V) is a small (22-24 nm) nonenveloped DNA virus belonging to the genus Erythrovirus (family Parvoviridae). Although it generally causes self-limiting conditions in healthy people, B19V infection may have a different outcome in patients with inherited hemolytic anemias. In such high-risk individuals, the high-titer replication may result in bone marrow suppression, triggering a life-threatening drop of hemoglobin values (profound anemia, aplastic crisis). To date there is no consensus concerning a B19V screening program either for the blood donations used in the hemotherapy or for high-risk patients. Moreover, questions such as the molecular mechanisms by which B19V produces latency and persistent replication, the primary site (sites) of B19V infection and B19V immunopathology are far from being known. This review summarizes general aspects of B19V molecular characteristics, pathogenesis and diagnostic approaches with a focus on the role of this pathogen in blood transfusions and in patients with some hemoglobinopathies (sickle-cell disease, thalassemia).

Reactivation of Polyomavirus hominis 1 (BKV) during pregnancy and the risk of mother-to-child transmission.

BACKGROUND Pregnancy is associated with down-regulation of immune responses of the mother. This might lead to reactivation and vertical transmission of latent viral infections such as BK virus (BKV). OBJECTIVES To determine the presence of BKV in the urine of pregnant women and in cord blood at delivery. STUDY DESIGN We examined urines from 52 pregnant women and 51 cord blood samples for BKV by real-time SYBR green PCR. RESULTS BKV DNA was found in the urine of 18 (34.6%) pregnant women. No BKV DNA was detected by SYBR green PCR in the cord blood specimens. CONCLUSIONS BKV reactivation is common during pregnancy but this is not associated with BKV in cord blood.

Molecular and phylogenetic analyses of human Parvovirus B19 isolated from Brazilian patients with sickle cell disease and β‐thalassemia major and healthy blood donors

Human Parvovirus B19 (B19V) is a recognized cause of life‐threatening conditions among patients with hemoglobinopathies. This study investigates B19V infection in patients with sickle cell disease and β‐thalassemia using different experimental approaches. A total of 183 individuals (144 with sickle cell disease and 39 with β‐thalassemia major) and 100 healthy blood donors were examined for B19V using anti‐B19V IgG enzyme immunoassay, quantitative PCR, DNA sequencing, and phylogenetic analysis. Viremia was documented in 18.6% of patients and 1% of donors, and was generally characterized by low viral load (VL); however, acute infections were also observed. Anti‐B19V IgG was detected in 65.9% of patients with sickle cell disease and in 60% of donors, whereas the patients with thalassemia exhibited relatively low seroreactivity. The seroprevalence varied among the different age groups. In patients, it progressively increased with age, whereas in donors it reached a plateau. Based on partial NS1 fragments, all isolates detected were classified as subgenotype 1A with a tendency to elicit genetically complex infections. Interestingly, quasispecies occurred in the plasma of not only patients but also donors with even higher heterogeneity. The partial NS1 sequence examined did not exhibit positive selection. Quantitation of B19V with a conservative probe is a technically and practically useful approach. The extensive spread of B19V subgenotype 1A in patients and donors and its recent introduction into the countryside of the São Paulo State, Brazil were demonstrated; however, it is difficult to establish a relationship between viral sequences and the clinical outcomes of the infection. J. Med. Virol. 84:1652–1665, 2012.

Zika virus RNA detection in asymptomatic blood donors during an outbreak in the northeast region of São Paulo State, Brazil, 2016: ZIKA VIRUS IN BRAZILIAN BLOOD DONORS

In 2015, there was a large Zika virus (ZIKV) outbreak in Brazil. The proportion of asymptomatic infections is very high, and it is possible for transfusion‐transmitted ZIKV (TT‐ZIKV) infection to occur. The prevalence of asymptomatic ZIKV infection among Brazilian blood donors during this epidemic outbreak is unknown.

Molecular and clinical evaluation of the acute human parvovirus B19 infection: comparison of two cases in children with sickle cell disease and discussion of the literature

Human parvovirus B19 is a well-known cause of severe conditions in patients with sickle cell disease, but the molecular mechanisms of the infection are insufficiently understood. The different clinical outcome of the acute parvovirus B19 infection in two pediatric patients with sickle cell disease has been examined. One of them developed life-threatening condition requiring emergency transfusions, while the other had asymptomatic infection, diagnosed occasionally. Both cases had high viral load and identical subgenotype, indicating that the viral molecular characteristics play a minimal role in the infection outcome.

Prevalence of Trypanosoma Cruzi antibodies in blood donors from the Sao Paulo State, Brazil, between 2012 and 2014

INTRODUCTION American tripanosomiasis (Chagas disease), the second most neglected disease in the world, is caused by the protozoan parasite Trypanosoma cruzi. Though natural transmission by insect vectors has been controlled, there is significant risk of T. cruzi transmission by blood transfusion in non-endemic regions, generally due to immigration processes from endemic areas. METHODOLOGY The objective of this study was to evaluate anti-T. cruzi seroprevalence in blood donors from the western part of São Paulo State, Brazil, by serologic and immunofluorescence confirmation tests for the period between 2012 and 2014. Currently, this region is regarded as a non-endemic area for Chagas disease. RESULTS The confirmed overall T. cruzi seroprevalence among blood donors was 0.10%, which can be considered low compared to other Brazilian regions. Nevertheless, the distribution of the anti-T. cruzi antibodies within the examined region was uneven, and some areas of significantly higher prevalence were observed. CONCLUSIONS We could consider two tendencies in the prevalence of T. cruzi: (i) residual older undiagnosed cases from São Paulo State, and (ii) immigration from endemic Brazilian or South American regions. The discordance obtained for T. cruzi prevalence by serologic and immunofluorescence methods demonstrates that more specific routine diagnosis is needed to diminish the cost of the assays and the loss of blood supply once all seropositive blood bags are immediately discarded.

Evaluation of human T-lymphotropic virus prevalence/co-infection rates for a four-year period in a non-metropolitan blood center in Southeast Brazil

INTRODUCTION Human T-lymphotropic virus types 1/2 (HTLV-1/2) are distributed worldwide and are endemic in specific regions. METHODS Serological evaluation of the HTLV-1/2 prevalence and co-infection rate [human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV), Chagas disease, and syphilis)] for 2011-2014 was performed with volunteer blood donors from the western part of São Paulo State. RESULTS Serrana and Araçatuba had higher HTLV seroprevalence rates (0.1%); while Franca, Olimpia, and Bebedouro had lower seroprevalences (0.04%). Co-infection (HBV and syphilis) was present in 12.3% of HTLV-infected blood donors. CONCLUSIONS Our findings provide data for the prevalence of HTLV in Brazil and demonstrate the importance of regional and global hemovigilance.

Effective Light-Upon-Extension Real-Time PCR Primer Systems for Rapid Detection of Human Viruses

Background: Real-time polymerase chain reaction (PCR) assays for quantitative detection and typing of viruses are fast, simple, and provide valuable information about the progression of an infection. Identification of human papilloma and polyomaviruses is used to estimate the risk of cancer (papilloma), polyomavirus-associated-nephropathy (BKV), or progressive multifocal leukoencephalopathy (JCV) in individual patients. Thus, non-invasive and specific diagnostics for viral detection should be regarded. Methods: We describe the design, optimization, and application of effective LightUpon Extension (LUX) real-time PCR systems for detection of papillomaviruses, BKV, and JCV. Viral and human controls along with clinical samples were examined during the optimization process. D-LUX designer software and the Opticon 2 Real-Time System (Bio-Rad, Hercules, CA) were used. Results: We confirm the specificity, rapidity, and non-invasiveness of the method for demonstration of ongoing replication. We believe LUX technology is comparable to probe based real-time PCR assays for the detection of viruses, but it has an advantage in terms of cost-effectiveness, convenience, and possibility for a dissociation analysis. Conclusions: The fluorogenic primer method (LUX) is rapid, uses few toxic chemicals, and is useful for the specific and accurate detection of viral DNA among different types of samples.

Late emergence of A594V and L595W mutations related to ganciclovir resistance in a patient with HCMV retinitis and long-term HIV progression.

The emergence of ganciclovir (GCV) resistance during the treatment of human cytomegalovirus (HCMV) infection is a serious clinical challenge, and is associated with high morbidity and mortality. In this case report, we describe the emergence of two consecutive mutations (A594V and L595W) related to GCV resistance in a patient with HCMV retinitis and long-term HIV progression after approximately 240 days of GCV use. Following the diagnosis of retinitis, the introduction of GCV did not result in viral load reduction. The detected mutations appeared late in the treatment, and we propose that other factors (high initial HCMV load, previous GCV exposure, low CD4+ cell count), in addition to the presence of resistance mutations, may have contributed to the treatment failure of HCMV infection in this patient.