Antivirals for human use against rabies and prospects for their future application.

Rabies is probably the deadliest and most severe encephalitis known to humankind. Caused by any lyssavirus, it is recognised as a disease of the poor, the less fortunate and the young. No other known infectious disease can cause 100% mortality, and rabies and the clinical manifestations which precede a death from the disease are often described as excruciating. Animals are not spared this deadly illness either, essentially every mammal can be infected with the virus, resulting in the development of lethal encephalitis. However, rabies is also one of the few infectious diseases that can be prevented through vaccination. Yet, its mortality figures are on the increase. Only a small number of patients have been reported to have survived rabies once infection has been established; a survival based on pre-/post-exposure prophylaxis, natural induction following infection or experimentation and the intuition of attending physicians, while available antivirals have previously been used without success. Therefore, the need for novel and innovative interventions is urgent. In this paper, the authors summarise past failures in treating the disease and highlight future hopes in the field of rabies treatment.

La rage est probablement la plus grave des encéphalites connues chez l'homme et celle qui fait le plus de victimes. L'infection rabique causée par un membre quelconque du genre Lyssavirus est reconnue comme une maladie affectant les pauvres, les déshérités et les enfants. Aucune autre maladie infectieuse connue n'entraîne une mortalité de 100 % comme la rage ; en outre, les manifestations cliniques qui précèdent la mort par rage sont souvent décrites comme étant extrêmement douloureuses. Les animaux ne sont pas épargnés par cette maladie mortelle puisque pratiquement tout mammifère peut être infecté par le virus et développer une encéphalite à l'issue mortelle. Néanmoins, la rage est aussi l'une des rares maladies infectieuses qu'il est possible de prévenir au moyen de la vaccination. Le nombre de décès par rage ne cesse pourtant d'augmenter. Un très petit nombre seulement de patients ont survécu à l'infection rabique, dans chaque cas grâce au traitement spécifique tenté à titre expérimental par des médecins intuitifs. En revanche, à ce jour l'utilisation d'agents antiviraux n'a jamais donné de résultats. Il est donc impératif de mettre au point des modalités d'intervention nouvelles et innovantes. Les auteurs résument les échecs enregistrés dans le passé en matière de traitements antirabiques tout en soulignant les aspects qui permettent d'espérer une évolution favorable dans ce domaine à l'avenir.

La rabia es probablemente la encefalitis más grave y mortífera que conoce la humanidad. Cualquier lisavirus puede causarla, y está reconocida como enfermedad de los pobres, los menos favorecidos y los jóvenes. No se sabe de ninguna otra patología infecciosa que pueda provocar una mortalidad del 100%, sin olvidar que la enfermedad y las manifestaciones clínicas previas al fallecimiento son descritas a menudo como atroces. Tampoco los animales escapan a esta deletérea dolencia: esencialmente, todo mamífero puede resultar infectado por el virus y contraer con ello una encefalitis letal. La rabia, empero, es también una de las pocas enfermedades infecciosas que pueden prevenirse mediante vacunación. Aun así, las cifras de mortalidad van en aumento. Contados son los casos descritos de pacientes que han sobrevivido a la rabia, supervivencia que reposó en la experimentación y la intuición de los médicos; en cambio, el uso de antivirales nunca dio resultados hasta ahora. De ahí la imperiosa necesidad de nuevas e innovadoras intervenciones. Los autores resumen aquí los métodos ensayados infructuosamente hasta ahora para tratar la enfermedad y apuntan a terapias esperanzadoras de cara al futuro.

The challenge of West Nile virus in Europe: knowledge gaps and research priorities.

West Nile virus (WNV) is continuously spreading across Europe, and other continents, i.e. North and South America and many other regions of the world. Despite the overall sporadic nature of outbreaks with cases of West Nile neuroinvasive disease (WNND) in Europe, the spillover events have increased and the virus has been introduced into new areas. The high genetic diversity of the virus, with remarkable phenotypic variation, and its endemic circulation in several countries, require an intensification of the integrated and multidisciplinary research efforts built under the 7th Framework Programme of the European Union (FP7). It is important to better clarify several aspects of WNV circulation in Europe, including its ecology, genomic diversity, pathogenicity, transmissibility, diagnosis and control options, under different environmental and socio-economic scenarios. Identifying WNV endemic as well as infection-free areas is becoming a need for the development of human vaccines and therapeutics and the application of blood and organs safety regulations. This review, produced as a joint initiative among European experts and based on analysis of 118 scientific papers published between 2004 and 2014, provides the state of knowledge on WNV and highlights the existing knowledge and research gaps that need to be addressed with high priority in Europe and neighbouring countries.

Increased PAI-1 plasma levels and risk of death from dengue: no association with the 4G/5G promoter polymorphism.

BACKGROUND: Dengue virus infected patients have high plasminogen activator inhibitor type I (PAI-1) plasma concentrations. Whether the insertion/deletion (4G/5G) polymorphism in the promotor region of the PAI-1 gene is associated with increased PAI-1 plasma concentrations and with death from dengue is unknown. We, therefore, investigated the relationship between the 4G/5G polymorphism and PAI-1 plasma concentrations in dengue patients and risk of death from dengue. METHODS: A total of 194 patients admitted to the Dr. Kariadi Hospital in Semarang, Indonesia, with clinical suspected severe dengue virus infection were enrolled. Blood samples were obtained on day of admission, days 1, 2 and 7 after admission and at a 1-month follow-up visit. Plasma concentrations of PAI-1 were measured using a sandwich ELISA kit. The PAI-1 4G/5G polymorphism was typed by allele-specific PCR analysis. RESULTS: Concentrations of PAI-1 on admission and peak values of PAI-1 during admission were higher than the values measured in healthy controls. Survival was significantly worse in patients with PAI-1 concentrations in the highest tertile (at admission: OR 4.7 [95% CI 0.9-23.8], peak value during admission: OR 6.3 [95%CI 1.3-30.8]). No association was found between the PAI-1 4G/5G polymorphism, and PAI-1 plasma concentrations, dengue disease severity and mortality from dengue. CONCLUSION: These data suggest that the 4G/5G polymorphism has no significant influence on PAI-1 concentrations in dengue virus infected patients and is not associated with the risk of death from dengue. Other factors contributing to the variability of PAI-1 plasma concentrations in patients with dengue need to be explored.

Serologic evidence of ehrlichiosis among humans and wild animals in The Netherlands.

The seroprevalence of antibodies directed against granulocytic and monocytic Ehrlichia was determined by use of human granulocytic ehrlichiosis agent and Ehrlichia chaffeensis as surrogate antigens. Seven hundred twenty-one serum samples were collected between 1992 and 1999 from febrile patients with unresolved aetiology (n=108), patients suspected of having Lyme disease (n=174), forestry workers (n=154) and healthy controls (n=54) as well as from wild deer (n=96), hares (n=60), wild boar (n=15) and red foxes (n=60). Reactive antibodies against granulocytic Ehrlichia were detected in 4% of febrile patients with unresolved aetiology and in 4% of patients suspected of having Lyme disease. Among the forestry workers, 1% tested positive for antibodies against granulocytic Ehrlichia, whereas all the healthy controls were negative. Antibody reaction against monocytic Ehrlichia was detected in only 2% of the febrile patients. Granulocytic Ehrlichia and monocytic Ehrlichia-reactive serum antibodies were detected in 22% and 3% of the deer samples, respectively, and in 2% of the hares. In wild boars and in red foxes, only serum antibodies reactive against monocytic Ehrlichia were detected in 13% and 7%, respectively. The demonstration of the presence of both granulocytic and monocytic Ehrlichia-reactive serum antibodies among humans and wild animals in The Netherlands indicates that patients suspected of having Lyme disease and febrile patients with unresolved aetiology should be tested for the presence of granulocytic and monocytic Ehrlichia antibodies or by polymerase chain reaction. Furthermore, granulocytic Ehrlichia are most prevalent in humans and animals in The Netherlands.

Kinetics of dengue virus-specific serum immunoglobulin classes and subclasses correlate with clinical outcome of infection.

The kinetics of dengue virus (DEN)-specific serum immunoglobulin classes (immunoglobulin M [IgM] and IgA) and subclasses (IgG1 to IgG4) were studied in patients suffering from dengue fever (DF), dengue hemorrhagic fever (DHF), and dengue shock syndrome (DSS). Serum samples from non-DEN febrile patients were included as controls. IgM, IgG1, and IgG3 serum antibodies were the predominant immunoglobulins throughout the course of illness in all three patient groups. In contrast, IgA antibodies were significantly higher in the acute phase in DSS patients compared to those in DF patients (P < 0.05). The levels of IgG1 differed significantly between patients with DF and those with DHF and DSS (P < 0.05). A significant difference was also found in IgG3 levels between DF patients and DHF patients (P < 0.05) but not between DF patients and DSS patients. Finally, levels of IgG4 antibodies differed significantly between DF patients and DSS patients (P < 0.05). Collectively, these data show that increased levels of DEN-specific IgA, IgG1, and IgG4 serum antibodies are risk markers for the development of DHF and DSS and that their measurement may provide valuable guidance for early therapeutic intervention.

Evaluation of six immunoassays for detection of dengue virus-specific immunoglobulin M and G antibodies.

The performance of six commercially available immunoassay systems for the detection of dengue virus-specific immunoglobulin M (IgM) and IgG antibodies in serum was evaluated. These included two IgM and IgG enzyme immunoassays (EIA) from MRL Laboratories and PanBio, a rapid immunochromatographic test (RIT) from PanBio, immunofluorescence assays (IFA) from Progen, a dot blot assay from Genelabs, and a dipstick EIA from Integrated Diagnostics (INDX). For this study a panel of 132 serum samples, including 90 serum samples from patients with suspected dengue virus infection and 42 serum samples from patients with other viral infections, was used. In addition, serial serum samples from two monkeys experimentally immunized and challenged with dengue virus type 2 were used. Results were considered conclusive when concordant results were obtained with four of the six antibody-specific assays. Based on this definition, the calculated overall agreement for the human serum samples for the respective IgM immunoassays was 97% (128 of 132), with 34% (45 of 132) positive serum samples, 63% (83 of 132) negative samples, and 3% of samples (4 of 132) showing discordant results. The calculated overall agreement for the IgG assays was 94% (124 of 132), with 49% (65 of 132) positive, 45% (59 of 132) negative, and 6% (8 of 132) discordant results, respectively. The sensitivities of the dengue virus-specific assays evaluated varied between 71 and 100% for IgM and between 52 and 100% for IgG, with specificities of 86 to 96% and 81 to 100%, respectively. The relative sensitivities of the respective IgM assays measured with the monkey serum samples were comparable with those obtained with 12 serial serum samples from humans. Overall performance, based on the sum of the agreement, sensitivity, specificity, and Kappa statistics of the IgM and IgG immunoassays, showed that the antibody detection systems from INDX and Genelabs and the MRL and PanBio EIA are useful and reliable assays for dengue virus serodiagnosis.

Evaluation of two commercially available immunoassays for the detection of hantavirus antibodies in serum samples.

BACKGROUND: hantaviruses are members of the family Bunyaviridae and the spectrum of clinical symptoms in humans may vary from sub-clinical to severe haemorrhagic fever with renal syndrome (HFRS) or pulmonary syndrome (HPS). Several serotypes have been described from which at least five are pathogenic to humans. Each serotype has a different animal reservoir and geographical distribution. In the acute phase of the disease the clinical diagnosis may be confirmed by serology or by polymerase-chain reaction (PCR). OBJECTIVE: to evaluate two commercially available immunoassays using sera from hantavirus suspected and non-hantavirus patients: an enzyme immunoassay (EIA) developed by MRL Diagnostics, for the detection of immunoglobulins M (IgM) and G (IgG) against several hantavirus serotypes and an indirect immunofluorescence assay (IFA) from Progen, based on slides coated with Hantaan virus (HNTV) and Puumala virus (PUUV), infected cells. STUDY DESIGN: a total of 145 serum samples were used for this study. The serum panel included serum samples from patients suspected of mild (n=91), severe (n=10) HFRS and patients with other viral infections (n=44). RESULTS: the agreement between the MRL EIA and the Progen IFA for the detection of IgM and IgG serum antibodies ranged from 87 to 91%, respectively. In the non-hantavirus group one out of 44 samples was positive by the Progen HNTV IgM IFA, none in the Progen PUUV IFA and two samples in the MRL IgM EIA, resulting in specificities of 98, 100 and 95%, respectively. The sensitivities and specificities of the MRL EIAs compared to the Progen overall PUUV and HNTV IFAs were 90 and 91% for IgM, respectively, and 96% for IgG in both immunoassays. CONCLUSIONS: the MRL EIA proved to be relatively sensitive and specific assay for the serological diagnosis of mild and severe HFRS.