Blood kinetics of Ebola virus in survivors and nonsurvivors

BACKGROUND. Infection with Ebola virus (EBOV) results in a life-threatening disease, with reported mortality rates between 50%–70%. The factors that determine patient survival are poorly understood; however, clinical observations indicate that EBOV viremia may be associated with fatal outcome. We conducted a study of the kinetics of Zaire EBOV viremia in patients with EBOV disease (EVD) who were managed at an Ebola Treatment Centre in Sierra Leone during the recent West African outbreak.METHODS. Data from 84 EVD patients (38 survivors, 46 nonsurvivors) were analyzed, and EBOV viremia was quantified between 2 and 13 days after symptom onset. Time since symptom onset and clinical outcome were used as independent variables to compare EBOV viral kinetics in survivors and nonsurvivors.RESULTS. In all patients, EBOV viremia kinetics was a quadratic function of time; however, EBOV viremia was 0.94 logarithm (log) copies per ml (cp/ml) (P = 0.011) higher in nonsurvivors than in survivors from day 2 after the onset of symptoms. Survivors reached peak viremia levels at an earlier time after symptom onset than nonsurvivors (day 5 versus day 7) and had lower mean peak viremia levels compared with nonsurvivors (7.46 log cp/ml; 95% CI, 7.17–7.76 vs. 8.60 log cp/ml; 95% CI, 8.27–8.93). Before reaching peak values, EBOV viremia similarly increased both in survivors and nonsurvivors; however, the decay of viremia after the peak was much stronger in survivors than in nonsurvivors.CONCLUSION. Our results demonstrate that plasma concentrations of EBOV are markedly different between survivors and nonsurvivors at very early time points after symptom onset and may be predicative of outcome. Further studies focused on the early phase of the disease will be required to identify the causal and prognostic factors that determine patient outcome.FUNDING. Italian Ministry of Health; Italian Ministry of Foreign Affairs; EMERGENCY’s private donations; and Royal Engineers for DFID–UK.     

埃博拉出血热

埃博拉出血热(EBHF)又称埃博拉病毒病,是一种由埃博拉病毒(EBOV)引起的严重的、高病死率的急性出血性传染病。自1976年首次发现EBOV以来,EBHF疫情在非洲多次流行。由于疫情发生地之一是在西非扎伊尔地区北部的埃博拉河附近的一个村庄,EBOV由此而命名。2014年2月EBHF肆虐西非,随之以惊人的速度迅速蔓延,世界卫生组织声明,到2014年11月9日为止,全球EBOV感染人数为14 098人,其中死亡5 160人,此次暴发流行的规模和严重程度已经远超过在非洲发生过的任何一次流行,之所以引起全世界的高度关注,应该说源于人类对EBOV的未知,以及其传染性之强、致死率之高和目前仍没有发现对抗EBOV的特效药物等。     

Use of an improved quantitative polymerase chain reaction assay to determine differences in human rhinovirus viral loads in different populations

Human rhinoviruses (HRV) frequently cause acute respiratory infections and chronic respiratory disease exacerbations. However, testing is not generally offered. We developed a modified HRV quantitative polymerase chain reaction (qPCR) assay to assess viral loads in the community and hospital patients. The assay had a lower limit of detection of 2 log₁₀ viral copies/mL and displayed linearity over 5 log₁₀ viral copies, with a lower limit of quantitation of 4 log₁₀ viral copies/mL. Mean viral loads (95% confidence interval) for hospitalized children, university students, and institutionalized elderly, were 7.08 log₁₀ viral copies/mL (6.7–7.5), 6.87 log₁₀ viral copies/mL (6.5–7.2), and 7.09 log₁₀ viral copies/mL (6.9–7.3), respectively (P = 0.67). Serial specimens of 14 university students showed a decrease of mean viral loads from 6.36 log₁₀ viral copies/mL on day 1 to 2.32 log₁₀ viral copies/mL 7 days past symptom onset (P < 0.001). Using an HRV qPCR, we showed that viral loads did not differ between the community and hospitalized populations and significantly decreased following symptoms onset in healthy individuals.     

What is Ebola?

On 23 March 2014, the World Health Organization first announced a new Ebola virus outbreak that started in December 2013 in the eastern part of the Republic of Guinea. Human infections shortly emerged in Liberia, Sierra Leone, and Nigeria. On 30 September 2014, the Centers for Disease Control and Prevention confirmed through laboratory testing the first Ebola virus infection diagnosed in the USA, in a patient who travelled from West Africa to Texas. On 6 October 2014, the first human infection occurring outside of Africa was reported, in a Spanish nurse who treated two priests, both of whom died, and on 23 October 2014, the first human infection was reported in New York City. To date, the 2014 Ebola virus outbreak is the longest, largest, and most persistent one since 1976, when the virus was first identified in humans, and the number of human cases exceeded, as of mid‐September 2014, the cumulative number of infections from all the previous outbreaks. The early clinical presentation overlaps with other infectious diseases, opening differential diagnosis difficulties. Understanding the transmission routes and identifying the natural reservoir of the virus are additional challenges in studying Ebola hemorrhagic fever outbreaks. Ebola virus is as much a public health challenge for developing countries as it is for the developed world, and previous outbreaks underscored that the relative contribution of the risk factors may differ among outbreaks. The implementation of effective preparedness plans is contingent on integrating teachings from previous Ebola virus outbreaks with those from the current outbreak and with lessons provided by other infectious diseases, along with developing a multifaceted inter‐disciplinary and cross‐disciplinary framework that should be established and shaped by biomedical as well as sociopolitical sciences.     

2013—2014年西非埃博拉病毒病流行特征分析

目的分析2014年发生在西非地区的埃博拉病毒病(Ebola virus disease,EVD)疫情流行特征,为制定中国防控策略和措施提供科学依据。方法根据世界卫生组织公布的疫情相关资料,采用描述性流行病学方法对资料进行分析。结果 2013年12月至2014年9月13日几内亚(Guinea)、利比里亚(Liberia)、塞拉利昂(Sierra Leone)、尼日利亚(Nigeria)和塞内加尔(Senegal)5国共报告EVD病例4985例,死亡2461例,病死率为49%。截至目前疫情整体呈现为两个阶段,第一阶段为2013年12月至2014年4月,疫情主要集中在几内亚;第二阶段为2014年5—9月,疫情主要影响几内亚、利比里亚和塞拉利昂;除尼日利亚外,其余4国彼此相邻,大面积陆路接壤。尼日利亚疫情是由1名利比里亚患者输入导致的继发感染,而塞内加尔报告的是1例几内亚病例。截至2014年9月13日,5个国家中医务人员感染人数近300人(约占总病例数的6%),死亡超过140例。基因分析显示,引发此次疫情的病毒是埃博拉病毒中扎伊尔型(Zaire ebolavirus)的一个独立分支。结论 2014年发生在西非地区的EVD暴发疫情是自1976年发现埃博拉病毒(Ebola virus,EBOV)以来最大的一次暴发,同时也是西非地区首次报告EVD疫情,目前形势分析认为疫情可能仍将持续6~9个月。     

Variability in patterns of BK viral load after renal transplantation

BK virus (BKV) may cause nephropathy in renal transplant patients, resulting in graft dysfunction and possible graft loss. We used a sensitive quantitative BKV assay to monitor plasma BK viral loads in 11 renal transplant patients for periods ranging from 37 to 189 weeks posttransplant. Five patients remained negative for BKV, and 6 developed viremia, including 1 patient with a transient viremia. Of the viremic patients, 2 were diagnosed with BKV nephropathy after increasing serial BK viral loads, prompting a renal biopsy that established the diagnosis. A 3rd patient had high initial BK viral load and biopsy-proven disease that resolved with reduced immunosuppression. Two patients did not develop nephropathy despite persistent viral loads of 10(4) copies/mL. Five of 6 patients experienced viral clearance from the plasma (BK viral load <500 copies/mL), which was associated with their renal function becoming stabilized, and the remaining patient experienced a downward trend in viral load and stable renal function. Thus, the BKV quantitative assay was useful in aiding the diagnosis of BKV nephropathy, monitoring the response to reductions in immunosuppression and identified that some patients can have persistent viremia and still develop stable renal function without specific antiviral therapy.     

Treatment-focused Ebola trials,supportive care and future of filovirus care

Introduction: During the 2014–2016 Ebolavirus (EBOV) outbreak, several candidate therapeutics were used in EBOV-infected patients in clinical trials and under expanded access for emergency use. This review will focus briefly on medications used during the outbreak. We will discuss current therapeutic candidates and their status and will then turn to a related and essential topic: supportive care and the standard of care for filovirus infected patients. Potential benefits and pitfalls of combination therapies for filoviruses will be discussed.

Areas covered: Clinical trials of therapeutics targeting EBOV; clinical usage of therapeutics during recent EBOV outbreak; potential need for combination therapy; role of supportive care in treatment of Ebola virus disease (EVD).

Expert commentary: In the absence of another large scale EBOV outbreak, the path to therapeutic product licensure in the United States of America (USA) would need to be via the FDA Animal Rule. However, human data may be needed to supplement animal data. The future of filovirus therapeutics may therefore benefit by establishing the ability to implement clinical trials in an outbreak setting in a timely fashion. Supportive care guidelines for filovirus infection should be defined and established as standard of care for treatment of EVD.     

Recent advances in the development and evaluation of molecular diagnostics for Ebola virus disease

Introduction: The 2014-16 outbreak of ebola virus disease (EVD) in West Africa resulted in 11,308 deaths. During the outbreak only 60% of patients were laboratory confirmed and global health authorities have identified the need for accurate and readily deployable molecular diagnostics as an important component of the ideal response to future outbreaks, to quickly identify and isolate patients.

Areas covered: Currently PCR-based techniques and rapid diagnostic tests (RDTs) that detect antigens specific to EVD infections dominate the diagnostic landscape, but recent advances in biosensor technologies have led to novel approaches for the development of EVD diagnostics. This review summarises the literature and available performance data of currently available molecular diagnostics for ebolavirus, identifies knowledge gaps and maps out future priorities for research in this field.

Expert opinion: While there are now a plethora of diagnostic tests for EVD at various stages of development, there is an acute need for studies to compare their clinical performance, but the sporadic nature of EVD outbreaks makes this extremely challenging, demanding pragmatic new modalities of research funding and ethical/institutional approval, to enable responsive research in outbreak settings. Retrospective head-to-head diagnostic comparisons could also be implemented using biobanked specimens, providing this can be done safely.     

Antiviral effects of lamivudine, emtricitabine, adefovir dipivoxil, and tenofovir disoproxil fumarate administered orally alone and in combination to woodchucks with chronic woodchuck hepatitis virus infection

Adefovir dipivoxil (ADV) and tenofovir disoproxil fumarate (TDF) are nucleotide analogs that inhibit the replication of wild-type hepatitis B virus (HBV) and lamivudine (3TC)-resistant virus in HBV-infected patients, including those who are coinfected with human immunodeficiency virus. The combination of ADV or TDF with other nucleoside analogs is a proposed strategy for managing antiviral drug resistance during the treatment of chronic HBV infection. The antiviral effect of oral ADV or TDF, alone or in combination with 3TC or emtricitabine (FTC), against chronic woodchuck hepatitis virus (WHV) infection was evaluated in a placebo-controlled study in the woodchuck, an established and predictive model for antiviral therapy. Once-daily treatment for 48 weeks with ADV plus 3TC or TDF plus FTC significantly reduced serum WHV viremia levels from the pretreatment level by 6.2 log₁₀ and 6.1 log₁₀ genome equivalents/ml serum, respectively, followed by TDF plus 3TC (5.6 log₁₀ genome equivalents/ml), ADV alone (4.8 log₁₀ genome equivalents/ml), ADV plus FTC (one survivor) (4.4 log₁₀ genome equivalents/ml), TDF alone (2.9 log₁₀ genome equivalents/ml), 3TC alone (2.7 log₁₀ genome equivalents/ml), and FTC alone (2.0 log₁₀ genome equivalents/ml). Individual woodchucks across all treatment groups also demonstrated pronounced declines in serum WHV surface antigen, characteristically accompanied by declines in hepatic WHV replication and the hepatic expression of WHV antigens. Most woodchucks had prompt recrudescence of WHV replication after drug withdrawal, but individual woodchucks across treatment groups had sustained effects. No signs of toxicity were observed for any of the drugs or drug combinations administered. In conclusion, the oral administration of 3TC, FTC, ADV, and TDF alone and in combination was safe and effective in the woodchuck model of HBV infection.     

From bench to almost bedside: the long road to a licensed Ebola virus vaccine

Introduction: The Ebola virus (EBOV) disease epidemic during 2014–16 in West Africa has accelerated the clinical development of several vaccine candidates that have demonstrated efficacy in the gold standard nonhuman primate (NHP) model, namely cynomolgus macaques.

Areas covered: This review discusses the pre-clinical research and if available, clinical evaluation of the currently available EBOV vaccine candidates, while emphasizing the translatability of pre-clinical data generated in the NHP model to clinical data in humans.

Expert opinion: Despite the existence of many successful EBOV vaccine candidates in the pre-clinical stages, only two platforms became the focus of Phase 2/3 efficacy trials in Liberia, Sierra Leone, and Guinea near the peak of the epidemic: the Vesicular stomatitis virus (VSV)-vectored vaccine and the chimpanzee adenovirus type 3 (ChAd3)-vectored vaccine. The results of three distinct clinical trials involving these candidates may soon pave the way for a licensed, safe and efficacious EBOV vaccine to help combat future epidemics.     

Comparison of the new Abbott Real Time CMV assay and the Abbott CMV PCR Kit for the quantitation of plasma cytomegalovirus DNAemia

CMV DNA loads measured by the new Abbott RealTime CMV PCR were significantly higher than those quantitated by the Abbott CMV PCR kit (approximately 1 log₁₀), and provided a better estimate of the actual CMV load present in plasma specimens as inferred by the use of the WHO standard.     

Hunting for predictive computational drug-discovery models

In the last decade, chikungunya virus has emerged from an obscure arbovirus that caused limited outbreaks of disease in Africa and Asia to the cause of a pandemic affecting millions of people and spanning five continents. Two separate chikungunya virus genotypes have been responsible for outbreaks during this period, including strains adapted to transmission in Aedes albopictus mosquitoes. Further spread of this virus into new regions of the Western Hemisphere is predicted during the present rainy season in the tropics, and recurrent viral introductions and disease outbreaks, as occurred in Réunion in 2010, should be expected. Chikungunya virus no longer simply threatens; it has arrived as a significant, global pathogen.     

Real-time polymerase chain reaction for diagnosis and quantitation of negative strand of chikungunya virus

Quantitative real-time polymerase chain reaction (qRT-PCR) is useful for diagnosis and studying virus replication. We developed positive- and negative-strand qRT-PCR assays to detect nsP3 of chikungunya virus (CHIKV), a positive-strand RNA alphavirus that causes epidemic fever, rash, and arthritis. The positive- and negative-strand qRT-PCR assays had limits of quantification of 1 and 3 log₁₀ RNA copies/reaction, respectively. Compared to a published E1 diagnostic assay using 30 laboratory-confirmed clinical samples, the positive-strand nsP3 qRT-PCR assay had higher R² and efficiency and detected more positive samples. Peak viral load of 12.9 log₁₀ RNA copies/mL was reached on day 2 of illness, and RNA was detectable up to day 9, even in the presence of anti-CHIKV IgM. There was no correlation between viral load and persistent arthralgia. The positive-strand nsP3 assay is suitable for diagnosis, while the negative-strand nsP3 assay, which uses tagged primers to increase specificity, is useful for study of active viral replication kinetics.     

Short-Term Monotherapy with IDX184, a Liver-Targeted Nucleotide Polymerase Inhibitor,in Patients with Chronic Hepatitis C Virus Infection

IDX184 is a liver-targeted prodrug of 2′-methylguanosine (2′-MeG) monophosphate. This study investigated the safety, tolerability, antiviral activity, and pharmacokinetics of IDX184 as a single agent in treatment-naïve patients with genotype-1 chronic hepatitis C virus (HCV) infection. Forty-one patients with baseline HCV RNA ≥ 5 log₁₀ IU/ml, alanine aminotransferase (ALT) ≤ 2.5× the upper limit of normal, and compensated liver disease were dosed. Sequential cohorts of 10 patients, randomized 8:2 (active:placebo), received 25, 50, 75, and 100 mg of IDX184 once daily for 3 days, with a 14-day follow-up. There were no safety-related treatment discontinuations or serious adverse events. The adverse events and laboratory abnormalities observed for IDX184- and placebo-treated patients were similar. At the end of the 3-day treatment period, changes from baseline in HCV RNA levels (means ± standard deviations) were −0.5 ± 0.6, −0.7 ± 0.2, −0.6 ± 0.3, and −0.7 ± 0.5 log₁₀ for the 25-, 50-, 75-, and 100-mg doses, respectively, while viral load remained unchanged for the pooled placebo patients (−0.05 ± 0.3 log₁₀). Patients with genotype-1a and patients with genotype-1b responded similarly. Serum ALT levels decreased, especially at daily doses ≥ 75 mg. During the posttreatment period, plasma viremia and serum aminotransferase levels returned to near pretreatment levels. No resistance mutations associated with IDX184 were detected. Plasma exposure of IDX184 and its nucleoside metabolite 2′-MeG was dose related and low. Changes in plasma viral load correlated with plasma exposure of 2′-MeG. In conclusion, the results from this proof-of-concept study show that small doses of the liver-targeted prodrug IDX184 were able to deliver significant antiviral activity and support further clinical evaluation of the drug candidate.     

Digallate dimers of (-)-epigallocatechin gallate inactivate herpes simplex virus

Topical microbicides are potentially an alternative method to vaccines for reducing the spread of herpes simplex virus (HSV). We have previously shown (S. Liu et al., Biochim. Biophys. Acta 1723:270–281, 2005) that the catechin (−)-epigallocatechin gallate (EGCG) inactivates HSV at neutral pH; however, to function in the female genital tract EGCG must also be effective at acidic pH. EGCG inactivated HSV-1 and HSV-2 at pH 8.0 by 3 log₁₀ to 4 log₁₀ but was ineffective at pH 5.7. The EGCG digallate dimers theasinensin A, P2, and theaflavin-3,3′-digallate (TF-3) inactivated both viruses by 3 log₁₀ to 4 log₁₀ at pH 5.7 and as much as 5 log₁₀ at pH 8.0. TF-3 inactivated HSV-1 and HSV-2 by 4 to 5 log₁₀ in the pH range of 4.0 to 5.7. Dimers with one gallate moiety had antiviral activity intermediate between the activities of EGCG and digallate dimers. Confocal and electron microscopy showed that theasinensin A did not damage Vero cells. All EGCG dimers inactivated enveloped viruses with class I, class II, and class III (HSV-1, HSV-2) fusion proteins more effectively than did monomeric EGCG. EGCG had no activity against the nonenveloped viruses tested, but TF-3 reduced the titer of 4 of 5 nonenveloped viruses by ≅2 to 3.5 log₁₀. Results also showed that HSV-1 glycoprotein B (gB) was aggregated more rapidly by theasinensin A than EGCG, which, when taken together with the nonenveloped virus data, suggests that dimers may inhibit the function of viral proteins required for infectivity. Digallate dimers of EGCG appear to have excellent potential as microbicidal agents against HSV at acidic and neutral pHs.     

Aerosolized Ebola vaccine protects primates and elicits lung-resident T cell responses

Direct delivery of aerosolized vaccines to the respiratory mucosa elicits both systemic and mucosal responses. This vaccine strategy has not been tested for Ebola virus (EBOV) or other hemorrhagic fever viruses. Here, we examined the immunogenicity and protective efficacy of an aerosolized human parainfluenza virus type 3–vectored vaccine that expresses the glycoprotein (GP) of EBOV (HPIV3/EboGP) delivered to the respiratory tract. Rhesus macaques were vaccinated with aerosolized HPIV3/EboGP, liquid HPIV3/EboGP, or an unrelated, intramuscular, Venezuelan equine encephalitis replicon vaccine expressing EBOV GP. Serum and mucosal samples from aerosolized HPIV3/EboGP recipients exhibited high EBOV-specific IgG, IgA, and neutralizing antibody titers, which exceeded or equaled titers observed in liquid recipients. The HPIV3/EboGP vaccine induced an EBOV-specific cellular response that was greatest in the lungs and yielded polyfunctional CD8⁺ T cells, including a subset that expressed CD103 (αE integrin), and CD4⁺ T helper cells that were predominately type 1. The magnitude of the CD4⁺ T cell response was greater in aerosol vaccinees. The HPIV3/EboGP vaccine produced a more robust cell-mediated and humoral immune response than the systemic replicon vaccine. Moreover, 1 aerosol HPIV3/EboGP dose conferred 100% protection to macaques exposed to EBOV. Aerosol vaccination represents a useful and feasible vaccination mode that can be implemented with ease in a filovirus disease outbreak situation.     

African horse sickness

ABSTRACT:

African Horse Sickness (AHS) is an orbiviral viral disease of equids, transmitted by Culicoides midges. Mainly seen in Africa, some outbreaks elsewhere have been extensive and the disease has over-wintered in southern Europe. The AHS virus is probably spread by Culicoides obsoletus, found in northern Europe. AHS causes severe disease, and mortality can be over 90%. At present there is no cure. Supportive nursing care should be given and stress minimised. Protecting horses from midges is difficult. The live attenuated polyvalent vaccine used in South Africa is not licensed for use in Europe, but new vaccines are currently being developed.