Specific Antiviral Therapy Research Articles

Identification of a Small Molecule That Compromises the Structural Integrity of Viroplasms and Rotavirus Double-Layered Particles.

Despite the availability of two attenuated vaccines, rotavirus (RV) gastroenteritis remains an important cause of mortality among children in developing countries, causing about 215,000 infant deaths annually. Currently, there are no specific antiviral therapies available. RV is a nonenveloped virus with a segmented double-stranded RNA genome. Viral genome replication and assembly of transcriptionally active double-layered particles (DLPs) take place in cytoplasmic viral structures called viroplasms. In this study, we describe strong impairment of the early stages of RV replication induced by a small molecule known as an RNA polymerase III inhibitor, ML-60218 (ML). This compound was found to disrupt already assembled viroplasms and to hamper the formation of new ones without the need for de novo transcription of cellular RNAs. This phenotype was correlated with a reduction in accumulated viral proteins and newly made viral genome segments, disappearance of the hyperphosphorylated isoforms of the viroplasm-resident protein NSP5, and inhibition of infectious progeny virus production. In in vitro transcription assays with purified DLPs, ML showed dose-dependent inhibitory activity, indicating the viral nature of its target. ML was found to interfere with the formation of higher-order structures of VP6, the protein forming the DLP outer layer, without compromising its ability to trimerize. Electron microscopy of ML-treated DLPs showed dose-dependent structural damage. Our data suggest that interactions between VP6 trimers are essential, not only for DLP stability, but also for the structural integrity of viroplasms in infected cells.IMPORTANCE Rotavirus gastroenteritis is responsible for a large number of infant deaths in developing countries. Unfortunately, in the countries where effective vaccines are urgently needed, the efficacy of the available vaccines is particularly low. Therefore, the development of antivirals is an important goal, as they might complement the available vaccines or represent an alternative option. Moreover, they may be decisive in fighting the acute phase of infection. This work describes the inhibitory effect on rotavirus replication of a small molecule initially reported as an RNA polymerase III inhibitor. The molecule is the first chemical compound identified that is able to disrupt viroplasms, the viral replication machinery, and to compromise the stability of DLPs by targeting the viral protein VP6. This molecule thus represents a starting point in the development of more potent and less cytotoxic compounds against rotavirus infection.

Recombinant Zika Virus Subunits Are Immunogenic and Efficacious in Mice.

Following the 2015 Zika virus (ZIKV) outbreaks in the South Pacific, Caribbean, and Americas, ZIKV has emerged as a serious threat due to its association with infantile microcephaly and other neurologic disorders. Despite an international effort to develop a safe and effective vaccine to combat congenital Zika syndrome and ZIKV infection, only DNA and mRNA vaccines encoding the precursor membrane (prM) and envelope (E) proteins, an inactivated-ZIKV vaccine, and a measles virus-based ZIKV vaccine are currently in phase I or II (prM/E DNA) clinical trials. A ZIKV vaccine based on a nonreplicating, recombinant subunit platform offers a higher safety profile than other ZIKV vaccine candidates but is still highly immunogenic, inducing high virus-neutralizing antibody titers. Here, we describe the production and purification of Drosophila melanogaster S2 insect cell-derived, soluble ZIKV E protein and evaluate its immunogenicity and efficacy in three different mouse strains. As expected, significant virus-specific antibody titers were observed when using formulations containing clinically relevant adjuvants. Immunized mice challenged with live virus demonstrate inhibition of virus replication. Importantly, plaque reduction neutralization tests (PRNTs) indicate the high-titer production of neutralizing antibodies, a correlate of protection in the defense against ZIKV infection. ZIKV challenge of immunocompetent mice led to full protection against viremia with two doses of adjuvanted vaccine candidates. These data demonstrate a proof of concept and establish recombinant subunit immunogens as an effective vaccine candidate against ZIKV infection. IMPORTANCE The recent outbreaks of Zika virus (ZIKV) infection in French Polynesia, the Caribbean, and the Americas have highlighted the severe neuropathological sequelae that such an infection may cause. The development of a safe, effective ZIKV vaccine is critical for several reasons: (i) the difficulty in diagnosing an active infection due to common nonspecific symptoms, (ii) the lack of a specific antiviral therapy, and (iii) the potentially devastating pathological effects of in utero infection. Moreover, a vaccine with an excellent safety profile, such as a nonreplicating, noninfectious vaccine, would be ideal for high-risk people (e.g., pregnant women, immunocompromised patients, and elderly individuals). This report describes the development of a recombinant subunit protein vaccine candidate derived from stably transformed insect cells expressing the ZIKV envelope protein in vitro, the primary antigen to which effective virus-neutralizing antibodies are engendered by immunized animals for several other flaviviruses; the vaccine candidate elicits effective virus-neutralizing antibodies against ZIKV and provides protection against ZIKV infection in mice.

Evidence for multiple-insecticide resistance in urban Aedes albopictus populations in southern China

BackgroundAedes albopictus (Skuse) is an invasive mosquito that has become an important vector of chikungunya, dengue and Zika viruses. In the absence of specific antiviral therapy or a vaccine, vector management is the sole method available for reducing Aedes-induced disease morbidity. Determining the resistance status of Ae. albopictus to insecticides and exploring the resistance mechanisms is essential for future vector control planning.MethodsAedes albopictus larvae and pupae were sampled from six sites (two sites each from urban, suburban and rural) in Guangzhou. The resistance bioassays were conducted against Bacillus thuringiensis israelensis (Bti): deltamethrin, propoxur and malathion for larvae; and deltamethrin, DDT, propoxur and malathion for adults. P450 monooxygenase (P450s), glutathione S-transferase (GSTs) and carboxylesterase (COEs) activities of adult mosquitoes were measured. Mutations at the knockdown resistance (kdr) gene were analyzed, and the association between kdr mutations and phenotypic resistance was tested.ResultsAdult bioassays revealed varied susceptibility against DDT, deltamethrin and propoxur in the six Ae. albopictus populations. Significantly lower mortality rates were found in urban populations than suburban and rural populations. Urban mosquito populations showed resistance against DDT, deltamethrin and propoxur, while one rural population was resistant to DDT. All populations tested were susceptible to malathion. Larval bioassays results indicated that all populations of Ae. albopictus were sensitive to the larvicide Bti and malathion. Resistance to deltamethrin and propoxur was common in larval populations. The F1534S and F1534 L mutations were found to be significantly associated with deltamethrin resistance. Biochemical assays indicated elevated detoxification enzyme activities in the field mosquito populations.ConclusionsAedes albopictus populations in Guangzhou, especially in urban areas, have developed resistance to the commonly used insecticides, primarily DDT and deltamethrin. This finding calls for resistance management and developing counter measures to mitigate the spread of resistance.

Lamp1 Increases the Efficiency of Lassa Virus Infection by Promoting Fusion in Less Acidic Endosomal Compartments.

ABSTRACTLassa virus (LASV) is an arenavirus whose entry into host cells is mediated by a glycoprotein complex (GPC) comprised of a receptor binding subunit, GP1, a fusogenic transmembrane subunit, GP2, and a stable signal peptide. After receptor-mediated internalization, arenaviruses converge in the endocytic pathway, where they are thought to undergo low-pH-triggered, GPC-mediated fusion with a late endosome membrane. A unique feature of LASV entry is a pH-dependent switch from a primary cell surface receptor (α-dystroglycan) to an endosomal receptor, lysosomal-associated membrane protein (Lamp1). Despite evidence that the interaction between LASV GP1 and Lamp1 is critical, the function of Lamp1 in promoting LASV infection remains poorly characterized. Here we used wild-type (WT) and Lamp1 knockout (KO) cells to show that Lamp1 increases the efficiency of, but is not absolutely required for, LASV entry and infection. We then used cell-cell and pseudovirus-cell surface fusion assays to demonstrate that LASV GPC-mediated fusion occurs at a significantly higher pH when Lamp1 is present compared to when Lamp1 is missing. Correspondingly, we found that LASV entry occurs through less acidic endosomes in WT (Lamp1-positive) versus Lamp1 KO cells. We propose that, by elevating the pH threshold for fusion, Lamp1 allows LASV particles to exit the endocytic pathway before they encounter an increasingly acidic and harsh proteolytic environment, which could inactivate a significant percentage of incoming viruses. In this manner Lamp1 increases the overall efficiency of LASV entry and infection.

Cytomegalovirus infection in immunocompetent adults: Is observation still the best strategy?

Cytomegalovirus (CMV) infection in immunocompetent patients generally resolves with few sequelae. However, it can cause severe and relapsing symptoms that can last for several weeks. Due to the self-limiting nature of CMV disease in immunocompetent individuals, criteria for specific antiviral therapy in this cohort are not well established. Additionally the adverse effect profile of currently available anti-CMV therapy limits its use in specific patient populations .We describe 3 immunocompetent adults who developed symptomatic CMV infection and were ill for several weeks. All patients had positive CMV viral assays and ultimately received anti-CMV therapy with significant improvement in symptoms within a few days of starting therapy. Choosing appropriate candidates for anti-CMV therapy, among mmunocompetent individuals, requires further research.

Murine Hepatitis Virus nsp14 Exoribonuclease Activity Is Required for Resistance to Innate Immunity

Coronaviruses (CoVs) are positive-sense RNA viruses that infect numerous mammalian and avian species and are capable of causing severe and lethal disease in humans. CoVs encode several innate immune antagonists that counteract the host innate immune response to facilitate efficient viral replication. CoV nonstructural protein 14 (nsp14) encodes 3'-to-5' exoribonuclease activity (ExoN), which performs a proofreading function and is required for high-fidelity replication. Outside of the order Nidovirales, arenaviruses are the only RNA viruses that encode an ExoN, which functions to degrade double-stranded RNA (dsRNA) replication intermediates. In this study, we tested the hypothesis that CoV ExoN also functions to antagonize the innate immune response. We demonstrate that viruses lacking ExoN activity [ExoN(-)] are sensitive to cellular pretreatment with interferon beta (IFN-β) in a dose-dependent manner. In addition, ExoN(-) virus replication was attenuated in wild-type bone marrow-derived macrophages (BMMs) and partially restored in interferon alpha/beta receptor-deficient (IFNAR-/-) BMMs. ExoN(-) virus replication did not result in IFN-β gene expression, and in the presence of an IFN-β-mediated antiviral state, ExoN(-) viral RNA levels were not substantially reduced relative to those of untreated samples. However, ExoN(-) virus generated from IFN-β-pretreated cells had reduced specific infectivity and decreased relative fitness, suggesting that ExoN(-) virus generated during an antiviral state is less viable to establish a subsequent infection. Overall, our data suggest murine hepatitis virus (MHV) ExoN activity is required for resistance to the innate immune response, and antiviral mechanisms affecting the viral RNA sequence and/or an RNA modification act on viruses lacking ExoN activity.IMPORTANCE CoVs encode multiple antagonists that prevent or disrupt an efficient innate immune response. Additionally, no specific antiviral therapies or vaccines currently exist for human CoV infections. Therefore, the study of CoV innate immune antagonists is essential for understanding how CoVs overcome host defenses and to maximize potential therapeutic interventions. Here, we sought to determine the contributions of nsp14 ExoN activity in the induction of and resistance to the innate immune response. We show that viruses lacking nsp14 ExoN activity are more sensitive than wild-type MHV to restriction by exogenous IFN-β and that viruses produced in the presence of an antiviral state are less capable of establishing a subsequent viral infection. Our results support the hypothesis that murine hepatitis virus ExoN activity is required for resistance to the innate immune response.

The rs738409 polymorphism of the PNPLA3 gene is associated with hepatic steatosis and fibrosis in Brazilian patients with chronic hepatitis C

BackgroundProspective studies have shown that 80% of acute hepatitis C virus (HCV) cases progress to chronic infection; approximately 10-20% of patients with these conditions will develop liver cirrhosis within 2 to 3 decades, and 1-5% will develop liver cancer. Some studies have indicated that the rs738409 polymorphism of the PNPLA3 gene is associated with steatosis and the progression of advanced fibrosis. This study assessed the contribution of the PNPLA3 rs738409 polymorphism with regard to the steatosis and degree of liver fibrosis in Brazilian patients diagnosed with chronic hepatitis C.MethodsA total of 290 patients were evaluated at the Clinics Hospital of the School of Medicine, University of São Paulo, between 2010 and 2015. The inclusion criteria were age ≥ 18 years and positive anti-HCV antibody and HCV RNA tests. The participants were evaluated based on medical consultation, blood tests, and liver biopsies conducted before specific antiviral therapies were applied. The associations between the rs738409 PNPLA3 gene polymorphism and steatosis and advanced fibrosis were tested under a recessive inheritance model using logistic regression analysis, including age, gender, BMI, ethnicity/color, HOMA-IR, alcohol intake, HCV genotype 3, and the rs58542926 TM6SF2 gene polymorphism as covariates.ResultsThe mean age of the patients was 54.9 years old (range, 28 to 82 years), and 124 (42.8%) patients were male; 226 (77.9%) were white, 43 (14.8%) were pardo, and 21 (7.2%) were black Brazilians. Of the patients included in this study, 133 (45.9%) presented with the CC genotype, 63 (21.7%) with the CG genotype, and 94 (32.4%) with the GG genotype of the PNPLA3 gene I148M variant. We observed that the associations between PNPLA3 rs738409 GG genotype and steatosis was significant (OR: 2.16; 95% CI 1.26-3.72). The same genotype was associated to advanced fibrosis too (OR:2.64; 95% CI 1.26-5.53).ConclusionsAssociations between the rs738409 polymorphism of the PNPLA3 gene genotype GG and hepatic steatosis and advanced fibrosis were observed. Studies are still needed to clarify the influence of these polymorphisms on hepatic steatosis and degree of fibrosis among individuals diagnosed with chronic hepatitis C.

Escape of Tick-Borne Flavivirus from 2'-C-Methylated Nucleoside Antivirals Is Mediated by a Single Conservative Mutation in NS5 That Has a Dramatic Effect on Viral Fitness.

Tick-borne encephalitis virus (TBEV) causes a severe and potentially fatal neuroinfection in humans. Despite its high medical relevance, no specific antiviral therapy is currently available. Here we demonstrate that treatment with a nucleoside analog, 7-deaza-2'-C-methyladenosine (7-deaza-2'-CMA), substantially improved disease outcomes, increased survival, and reduced signs of neuroinfection and viral titers in the brains of mice infected with a lethal dose of TBEV. To investigate the mechanism of action of 7-deaza-2'-CMA, two drug-resistant TBEV clones were generated and characterized. The two clones shared a signature amino acid substitution, S603T, in the viral NS5 RNA-dependent RNA polymerase (RdRp) domain. This mutation conferred resistance to various 2'-C-methylated nucleoside derivatives, but no cross-resistance was seen with other nucleoside analogs, such as 4'-C-azidocytidine and 2'-deoxy-2'-beta-hydroxy-4'-azidocytidine (RO-9187). All-atom molecular dynamics simulations revealed that the S603T RdRp mutant repels a water molecule that coordinates the position of a metal ion cofactor as 2'-C-methylated nucleoside analogs approach the active site. To investigate its phenotype, the S603T mutation was introduced into a recombinant TBEV strain (Oshima-IC) generated from an infectious cDNA clone and into a TBEV replicon that expresses a reporter luciferase gene (Oshima-REP-luc2A). The mutants were replication impaired, showing reduced growth and a small plaque size in mammalian cell culture and reduced levels of neuroinvasiveness and neurovirulence in rodent models. These results indicate that TBEV resistance to 2'-C-methylated nucleoside inhibitors is conferred by a single conservative mutation that causes a subtle atomic effect within the active site of the viral NS5 RdRp and is associated with strong attenuation of the virus.IMPORTANCE This study found that the nucleoside analog 7-deaza-2'-C-methyladenosine (7-deaza-2'-CMA) has high antiviral activity against tick-borne encephalitis virus (TBEV), a pathogen that causes severe human neuroinfections in large areas of Europe and Asia and for which there is currently no specific therapy. Treating mice infected with a lethal dose of TBEV with 7-deaza-2'-CMA resulted in significantly higher survival rates and reduced the severity of neurological signs of the disease. Thus, this compound shows promise for further development as an anti-TBEV drug. It is important to generate drug-resistant mutants to understand how the drug works and to develop guidelines for patient treatment. We generated TBEV mutants that were resistant not only to 7-deaza-2'-CMA but also to a broad range of other 2'-C-methylated antiviral medications. Our findings suggest that combination therapy may be used to improve treatment and reduce the emergence of drug-resistant viruses during nucleoside analog therapy for TBEV infection.

A scoring model for predicting prognosis of patients with severe fever with thrombocytopenia syndrome.

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging epidemic infectious disease caused by the SFTS bunyavirus (SFTSV) with an estimated high case-fatality rate of 12.7% to 32.6%. Currently, the disease has been reported in mainland China, Japan, Korea, and the United States. At present, there is no specific antiviral therapy for SFTSV infection. Considering the higher mortality rate and rapid clinical progress of SFTS, supporting the appropriate treatment in time to SFTS patients is critical. Therefore, it is very important for clinicians to predict these SFTS cases who are more likely to have a poor prognosis or even more likely to decease. In the present study, we established a simple and feasible model for assessing the severity and predicting the prognosis of SFTS patients with high sensitivity and specificity. This model may aid the physicians to immediately initiate prompt treatment to block the rapid development of the illness and reduce the fatality of SFTS patients.

Cytomegalovirus reactivation in lymphoma and myeloma patients undergoing autologous peripheral blood stem cell transplantation

BackgroundCytomegalovirus reactivation is often diagnosed in allogeneic hematopoietic cell transplant recipients and therefore could lead to CMV-related disease, involving many organs in these immunocompromised patients. In contrast, few studies investigated CMV reactivation and end-organ disease in patients undergoing Autologous Peripheral Blood Stem Cell Transplant (ASCT) since they are considered at low risk for both reactivation and disease. ObjectivesThe primary outcome of the analysis was to understand the difference in incidence of CMV reactivation between MM and Lymphoma patients. Secondary outcomes included the difference between MM and Lymphoma patients when considering the effect of CMV reactivation on transplant related mortality (TRM) overall survival (OS) progression free survival (PFS), risk factors for reactivation, and median time to reactivation. Study designIn this report, we retrospectively compared the incidence, risk factors, and outcome of CMV reactivation in adult patients with Myeloma (MM) and Lymphoma undergoing ASCT at the American university of Beirut Medical Center in Lebanon (AUBMC). A total of 324 consecutive ASCT were performed between January 2005 and March 2016. Serial weekly monitoring for CMV quantification was done using a quantitative PCR, starting from transplantation until the hospital discharge and afterwards based on the clinical symptoms in cases of clinical suspicion of reactivation after discharge from the hospital. ResultsThe cumulative incidence of CMV reactivation was 16% (n=53) with a median time of 16 (range, 4–242) days after ASCT. The incidence of reactivation was significantly higher in the MM (22%) and NHL (20%) groups, when compared to the HL (4%) (P=0.001). There was a higher incidence of CMV reactivation according to age (≥50 vs ≤50 years) with higher incidence in the older population 24% vs 10% respectively (p=0.0043). The mean time to CMV reactivation was significantly higher in the NHL group with a mean of 53.7days when compared to the HL and MM groups with mean 19.75days and 12.66 (range, 4–34) days respectively (P=0.003). Twenty-two patients (76%) and three patients (75%) patients required specific antiviral therapy in the MM group and HL groups respectively; which was significantly higher (P<0.001) then the NHL group with 13 (65%) patients requiring specific antiviral therapy.Five patients (1.5%) developed CMV disease at a median of 60days (range, 7–107) post ASCT: there was significant difference in the mean-time to reactivation based on disease type MM versus lymphoma 10 versus 33days (P=0.007).In multivariate analysis, a higher age was associated with an increased risk of CMV reactivation; MM and NHL had higher risk of CMV reactivation when compared to HL, and progressive disease at transplant was associated with increased risk of CMV reactivation.After a median follow-up of 21.5 months (range: 1–125), there was no significant impact on PFS, however there was significant decrease in OS of lymphoma patients who had CMV reactivation when compared to those without CMV reactivation (204 and 112days respectively P=0.045). TRM increased from 1.1% in patients with no CMV reactivation to 13% in patients with CMV reactivation (P=0.003). ConclusionOur data suggests that CMV reactivation is not uncommon in ASCT recipients and may contribute to increase TRM. MM patients may have a higher incidence, of CMV reactivation with more anti-viral treatment requirements when compared to lymphoma patients, especially in older population.

Antiviral combination therapy for cytomegalovirus infection in high-risk infants.

Cytomegalovirus (CMV) infection is a major risk factor for mortality in infants with severe combined immunodeficiency (SCID) and other profound immune defects. Specific antiviral therapy must be initiated early and aggressively because of the potential for antiviral resistance, rapid dissemination and poor transplant outcomes. Combination antiviral therapy is routinely administered for some viral infections, but the value of this approach for the treatment of CMV is unclear. Here we explore a strategy of initial combination therapy for high-risk infants with CMV infection. We reviewed medical records of infants ≤6 months of age hospitalized between 2007-2015 who received ganciclovir (GCV) or foscarnet (FOS) monotherapy or initial combination GCV + FOS for CMV disease. The combination therapy group consisted of severely immunocompromised infants being considered for haematopoietic cell transplantation (HCT). Four patients received initial combination antiviral therapy and 26 patients received initial monotherapy during the study period. Combination antiviral recipients demonstrated initial improvement in viraemia and two of three who continued with this therapy survived the infection. Clinically significant resistance mutations did not emerge. Toxicity was common; neutropenia, thrombocytopenia and electrolyte abnormalities were the most frequent adverse events in both groups. Creatinine elevation was uncommon in both groups. Combination GCV + FOS therapy may be a safe alternative to monotherapy in high-risk infants, especially those who are pre-transplant with primary immune deficiency syndromes and high viral loads.

Abstract CT028: Adoptive transfer of CMV- and EBV- specific peptide-stimulated T cells after allogeneic stem cell transplantation: A Phase I/IIa clinical trial

Abstract Allogeneic stem cell transplantation (ASCT) to date is the only permanent curative treatment for many hematological cancers. Besides the development of Graft versus Host disease (GvHD), infections are the major adverse effect of ASCT. Specifically, reactivation of viruses is highly problematic in the aftermath of ASCT. Reactivation of human CMV and EBV negatively impacts on outcome after ASCT. 40-50% of patients reactivate CMV following ASCT, while the only CMV specific antiviral therapy available is ganciclovir, with other drugs being used off-label. For the 20-30% of patients reactivating EBV, only rituximab is available to control EBV. Rituximab leads to long term B-cell depletion requiring frequent administration of immunoglobulins. To cover this unmet medical need of CMV and EBV control after ASCT, we investigate a somatic cell therapy approach by adoptive transfer of CMV- and EBV-specific peptide-stimulated T cells. We specifically are scrutinizing the effect of application of the cells to prevent virus reactivation before its onset or preemptively at the early stages of viral infection. We set up a prospective randomized controlled phase I/IIa multi-center clinical trial to evaluate the safety and efficacy of preventive and preemptive adoptive transfer of this ATMP in patients after ASCT (EudraCT number 2012-004240-30). The design of the trial allows to applicate low numbers of activated T cells, thereby reducing the potential risks of GvHD for the recipient of adoptively transferred T cells. The multi-center trial is currently recruiting, so far, 13 patients have been randomized. ASCT patients are randomly assigned to the intervention or control group. Subjects of the control group receive standard of care. For all subjects of the intervention group, a personalized cell product (ATMP) containing a standardized number of virus specific T cells is manufactured from an aliquot of the leukapheresis product previously used for ASCT and cryopreserved until being administered. Subjects receive the cell product in intervals of at least 30 days, starting with the first adoptive transfer 30 days after ASCT at the earliest. Cells are transferred as preventive, preemptive, or also as therapeutic treatment. Subjects are monitored for occurrence of GvHD, for viral load, as well as for immune reconstitution and composition of the TCR pool, especially of virus-specific T cells. Citation Format: Michael Aigner, Regina Gary, Andreas Moosmann, Stefanie Maas, Julian Strobl, Robert Zimmermann, Jürgen Zingsem, Anita Kremer, Andreas Mackensen, Armin Gerbitz. Adoptive transfer of CMV- and EBV- specific peptide-stimulated T cells after allogeneic stem cell transplantation: A Phase I/IIa clinical trial [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr CT028. doi:10.1158/1538-7445.AM2017-CT028

MERS: an emerging disease of the 21st century

Between September 2012 and March 2017, the Middle East Respiratory Syndrome (MERS), caused by an infection with the MERS coronavirus (MERS-CoV), has been responsible for 1,931 laboratory-confirmed cases and at least 741 related-deaths. Despite the paucity of knowledge on the source and route of transmission, the evidence currently points to dromedary camels. Moreover, the incubation period for this disease ranges from two to sixteen days. The symptomatology of MERS-CoV is non-specific and cases are easily misdiagnosed. As most respiratory illnesses, no specific anti-viral therapies have been effective to date for the treatment of MERS. Currently, the WHO does not advise any travel or trade restrictions regarding MERS-CoV. However, the poor practice of infection control has reflected the association between the healthcare setting and the spike of disease occurrence, especially among patients. Interestingly, the adoption of the “one health” approach is critical to establish a more holistic understanding of this epidemic. Additionally, implementing strategies aimed at risk reduction of animal-to-human transmission, rapid case finding, adequate infection control, and contact tracing are key in the control and prevention of MERS-CoV.

РОЛЬ ПЕРВИННОЇ МЕДИЧНОЇ ДОПОМОГИ ХВОРИМ НА ГЕМОКОНТАКТНІ ІНФЕКЦІЇ (ВІЛ-ІНФЕКЦІЯ ТА ГЕПАТИТИ В і С)

Проаналізовано існуючі проблеми надання медичної допомоги хворим на ВІЛ-інфекцію та гемоконтактні вірусні гепатити в Україні. Показані роль первинної медичної допомоги у веденні пацієнтів даної категорії, основні завдання, які стоять перед сімейними лікарями. Також відзначені досягнуті успіхи в реалізації державної програми лікування хронічних вірусних гепатитів, розширенні доступу пацієнтів до отримання специфічної противірусної терапії.

The Race To Find Antivirals for Zika Virus.

Zika virus (ZIKV), a flavivirus transmitted by mosquitoes, was an almost neglected pathogen until its introduction in the Americas in 2015 and its subsequent explosive spread throughout the continent, where it has infected millions of people. The virus has caused social and sanitary alarm, mainly due to its association with severe neurological disorders (Guillain-Barré syndrome and microcephaly in fetuses and newborns). Nowadays, no specific antiviral therapy against ZIKV is available. However, during the past months, a great effort has been made to search for antiviral candidates using different approaches and methodologies, ranging from testing specific compounds with known antiviral activity to the screening of libraries with hundreds of bioactive molecules. The identified antiviral candidates include drugs targeting viral components as well as cellular ones. Here, an updated review of what has been done in this line is presented.

Human parechovirus type 3 infection: An emerging infection in neonates and young infants.

Human parechoviruses (HPeVs) are RNA viruses that have characteristics similar to those of enteroviruses and usually cause mild respiratory or gastrointestinal symptoms. Human parechovirus type 3 (HPeV3), first reported in 2004, is exceptional because it can provoke sepsis and meningoencephalitis leading to neurological sequelae, and even death, in neonates and young infants. Pediatricians and researchers are increasingly aware that HPeV3 is responsible for serious disease in neonates and young infants. Retrospective studies and several reports of epidemics of HPeV3 infection have provided data on epidemiology, clinical symptoms and signs, laboratory findings, and outcomes. However, the pathogenesis of HPeV3 infection remains unclear, which explains the lack of specific antiviral therapy and effective prevention measures. Maternal antibodies are important in protection against severe HPeV3-related disease, and this may be a clue regarding its pathogenesis. HPeV3 epidemics are likely to continue, and because the clinical manifestations of HPeV3 are severe, determining the pathogenesis of HPeV3 infection and establishing specific antiviral therapies are important goals for future research.

Zika Virus Infection in Pregnant Women and Microcephaly.

From the discovery of the Zika virus (ZIKV) in 1947 in Uganda (Africa), until its arrival in South America, it was not known that it would affect human reproductive life so severely. Today, damage to the central nervous system is known to be multiple, and microcephaly is considered the tip of the iceberg. Microcephaly actually represents the epilogue of this infection's devastating process on the central nervous system of embryos and fetuses. As a result of central nervous system aggression by the ZIKV, this infection brings the possibility of arthrogryposis, dysphagia, deafness and visual impairment. All of these changes of varying severity directly or indirectly compromise the future life of these children, and are already considered a congenital syndrome linked to the ZIKV. Diagnosis is one of the main difficulties in the approach of this infection. Considering the clinical part, it has manifestations common to infections by the dengue virus and the chikungunya fever, varying only in subjective intensities. The most frequent clinical variables are rash, febrile state, non-purulent conjunctivitis and arthralgia, among others. In terms of laboratory resources, there are also limitations to the subsidiary diagnosis. Molecular biology tests are based on polymerase chain reaction (PCR) with reverse transcriptase (RT) action, since the ZIKV is a ribonucleic acid (RNA) virus. The RT-PCR shows serum or plasma positivity for a short period of time, no more than five days after the onset of the signs and symptoms. The ZIKV urine test is positive for a longer period, up to 14 days. There are still no reliable techniques for the serological diagnosis of this infection. If there are no complications (meningoencephalitis or Guillain-Barré syndrome), further examination is unnecessary to assess systemic impairment. However, evidence is needed to rule out other infections that also cause rashes, such as dengue, chikungunya, syphilis, toxoplasmosis, cytomegalovirus, rubella, and herpes. There is no specific antiviral therapy against ZIKV, and the therapeutic approach to infected pregnant women is limited to the use of antipyretics and analgesics. Anti-inflammatory drugs should be avoided until the diagnosis of dengue is discarded. There is no need to modify the schedule of prenatal visits for pregnant women infected by ZIKV, but it is necessary to guarantee three ultrasound examinations during pregnancy for low-risk pregnancies, and monthly for pregnant women with confirmed ZIKV infection. Vaginal delivery and natural breastfeeding are advised.

Zika virus infection in pregnancy

The Zika virus is a flavivirus spread by mosquitoes. Its primary vectors are the Aedes aegypti and the Aedes albopictus. Before 2007 it sporadically caused benign morbidity. Since 2015, it started spreading "explosively" in America, especially in Brazil. In August 2016 they reported cases from New York and Poland, too. Most of the infections don't produce any symptoms, but can cause grave complications. The most important lesion is microcephalia that forms in fetuses. Microcephalia's most serious consequence is mental retardation, which puts great burden on both the family and the society. The viral infection increases the incidence of Guillain-Barré syndrome. This is an acute autoimmune disease which causes demyelination and, in the worst cases, it can also be fatal. Yet we do not possess adequate and specific vaccination nor antiviral therapy, although, since July 2016, the effectiveness of a DNA based vaccine is being tested on humans. More than half of the world's population lives in areas contaminated by infected mosquitoes so there is a great need for the development of an effective method against the vector mosquitoes. Sadly, even the vector control strategies aren't effective enough to push back the epidemic. Pregnant or fertile women must take the highest precautions against mosquito bites, especially if they travel to regions ravaged by the epidemic. The safest solution would be to postpone both the trip and the childbearing. In Europe, the vectors aren't spread enough to cause major threat, except maybe the warmer regions bordered by the Mediterranean Sea. However, it is possible that in the near future other viruses spread by Aedes mosquitoes could appear. Naturally, the travellers and immigrants, who came from endemic regions can also contribute to the spread of the epidemic. Thanks to the changes in global weather, there were reported findings of mosquitoes of the Aedes albopictus species in Hungary, which are slowly invading the continent, although we do not have information about their settlement in the country. The doctors may encounter introduced cases and we do not have to fear the spreading of the epidemic to our country, but in the bordering Slovakia and Slovenia infections have been reported. The future of the Zika virus is yet unpredictable, although looking at the global spread of the Dengue and Chikungunya viruses, a worldwide spread is expectable in the near future. Orv. Hetil., 2017, 158(15), 563-571.

Recent Advances in Developing Antiviral Therapies for Respiratory Syncytial Virus.

Respiratory syncytial virus (RSV) infection presents a significant health challenge in small children, the elderly and immunocompromised patients. There is still a high unmet medical need among patients with RSV infection, and no specific antiviral therapy is available. The only approved agents are palivizumab, which has to be given prophylactically, mainly in high-risk infants, and ribavirin, which is rarely used due to toxicity concerns and questionable benefits. Efforts to develop new antiviral agents have been hampered by the perceived need for high safety hurdles in pediatric patient populations use and the lack of well-characterized druggable targets. Despite these challenges, significant progress has been made in discovering multiple classes of inhibitors targeting various stages of the viral life cycle. Several recent proof-of-concept human studies with specific antivirals have shown promising results and completely reinvigorated the field. In this review we discuss the current status of RSV drug development, remaining challenges and future directions.

Biological Control Strategies for Mosquito Vectors of Arboviruses.

Historically, biological control utilizes predatory species and pathogenic microorganisms to reduce the population of mosquitoes as disease vectors. This is particularly important for the control of mosquito-borne arboviruses, which normally do not have specific antiviral therapies available. Although development of resistance is likely, the advantages of biological control are that the resources used are typically biodegradable and ecologically friendly. Over the past decade, the advancement of molecular biology has enabled optimization by the manipulation of genetic materials associated with biological control agents. Two significant advancements are the discovery of cytoplasmic incompatibility induced by Wolbachia bacteria, which has enhanced replacement programs, and the introduction of dominant lethal genes into local mosquito populations through the release of genetically modified mosquitoes. As various arboviruses continue to be significant public health threats, biological control strategies have evolved to be more diverse and become critical tools to reduce the disease burden of arboviruses.