Molekulare Diagnostik, Therapie und Epidemiologie von Erregern viraler hämorrhagischer Fieber unter besonderer Berücksichtigung des Lassa-Virus

Viral hemorrhagic fevers are a severe problem for public health systems especially in remote tropical areas. Lassa fever, caused by Lassa virus, is endemic in West-Africa. Several hundred thousand cases occur every year. Laboratory diagnostics is essential to reliably diagnose the disease and differentiate it from other febrile infections. The first part of this work describes the development and evaluation of test-systems to detect Lassa virus RNA in clinical samples. Therapy of Lassa fever is limited to supportive measures and treatment with Ribavirin. Several mechanisms of action are discussed to be responsible for the inhibition of Lassa virus by Ribavirin in cell culture. The second part of this work shows that the inhibition of the inosine monophosphate dehydrogenase is not the responsible mechanism if action. In the last part, the molecular epidemiology of Lassa virus in West-Africa is discussed and both a geographic and a temporal analysis of Lassa virus evolution are presented

Molecular Diagnostics for Lassa Fever at Irrua Specialist Teaching Hospital, Nigeria: Lessons Learnt from Two Years of Laboratory Operation

Background: Lassa fever is a viral hemorrhagic fever endemic in West Africa. However, none of the hospitals in the endemic areas of Nigeria has the capacity to perform Lassa virus diagnostics. Case identification and management solely relies on non-specific clinical criteria. The Irrua Specialist Teaching Hospital (ISTH) in the central senatorial district of Edo State struggled with this challenge for many years. Methodology/Principal Findings A laboratory for molecular diagnosis of Lassa fever, complying with basic standards of diagnostic PCR facilities, was established at ISTH in 2008. During 2009 through 2010, samples of 1,650 suspected cases were processed, of which 198 (12%) tested positive by Lassa virus RT-PCR. No remarkable demographic differences were observed between PCR-positive and negative patients. The case fatality rate for Lassa fever was 31%. Nearly two thirds of confirmed cases attended the emergency departments of ISTH. The time window for therapeutic intervention was extremely short, as 50% of the fatal cases died within 2 days of hospitalization—often before ribavirin treatment could be commenced. Fatal Lassa fever cases were older (p = 0.005), had lower body temperature (p<0.0001), and had higher creatinine (p<0.0001) and blood urea levels (p<0.0001) than survivors. Lassa fever incidence in the hospital followed a seasonal pattern with a peak between November and March. Lassa virus sequences obtained from the patients originating from Edo State formed—within lineage II—a separate clade that could be further subdivided into three clusters. Conclusions/Significance: Lassa fever case management was improved at a tertiary health institution in Nigeria through establishment of a laboratory for routine diagnostics of Lassa virus. Data collected in two years of operation demonstrate that Lassa fever is a serious public health problem in Edo State and reveal new insights into the disease in hospitalized patients.Organismic and Evolutionary Biolog

Novel Arenavirus Sequences in Hylomyscus sp. and Mus (Nannomys) setulosus from Côte d'Ivoire: Implications for Evolution of Arenaviruses in Africa

This study aimed to identify new arenaviruses and gather insights in the evolution of arenaviruses in Africa. During 2003 through 2005, 1,228 small mammals representing 14 different genera were trapped in 9 villages in south, east, and middle west of Côte d'Ivoire. Specimens were screened by pan-Old World arenavirus RT-PCRs targeting S and L RNA segments as well as immunofluorescence assay. Sequences of two novel tentative species of the family Arenaviridae, Menekre and Gbagroube virus, were detected in Hylomyscus sp. and Mus (Nannomys) setulosus, respectively. Arenavirus infection of Mus (Nannomys) setulosus was also demonstrated by serological testing. Lassa virus was not found, although 60% of the captured animals were Mastomys natalensis. Complete S RNA and partial L RNA sequences of the novel viruses were recovered from the rodent specimens and subjected to phylogenetic analysis. Gbagroube virus is a closely related sister taxon of Lassa virus, while Menekre virus clusters with the Ippy/Mobala/Mopeia virus complex. Reconstruction of possible virus–host co-phylogeny scenarios suggests that, within the African continent, signatures of co-evolution might have been obliterated by multiple host-switching events

Molecular diagnostics, therapy and epidemiology of agents causing viral hemorrhagic fevers with special regard to Lassa virus

Viral hemorrhagic fevers are a severe problem for public health systems especially in remote tropical areas. Lassa fever, caused by Lassa virus, is endemic in West-Africa. Several hundred thousand cases occur every year. Laboratory diagnostics is essential to reliably diagnose the disease and differentiate it from other febrile infections. The first part of this work describes the development and evaluation of test-systems to detect Lassa virus RNA in clinical samples. Therapy of Lassa fever is limited to supportive measures and treatment with Ribavirin. Several mechanisms of action are discussed to be responsible for the inhibition of Lassa virus by Ribavirin in cell culture. The second part of this work shows that the inhibition of the inosine monophosphate dehydrogenase is not the responsible mechanism if action. In the last part, the molecular epidemiology of Lassa virus in West-Africa is discussed and both a geographic and a temporal analysis of Lassa virus evolution are presented

Human HLA class II restricted epitopes against pathogenic arenaviruses.

<p>Italics, predicted restriction only. GTOV, Guanarito virus; JUNV, Junin virus; LASV, Lassa virus; LCMV, lymphocytic choriomeningitis virus; MACV, Machupo virus.</p

Human HLA class I restricted epitopes against pathogenic arenaviruses.

<p>Italics, predicted restriction only. GTOV, Guanarito virus; JUNV, Junin virus; LASV, Lassa virus; LCMV, lymphocytic choriomeningitis virus; MACV, Machupo virus.</p

Endemic regions for the pathogenic arenaviruses mentioned in the text.

<p>The color intensity indicates the population density. Lassa virus is clearly endemic in the most populated region of Africa; a vaccine is therefore of high relevance for public health. The map is available under a Creative Commons license (<a href="http://www.flickr.com/photos/54545503N04/5485517485/sizes/o/in/photostream/" target="_blank">http://www.flickr.com/photos/54545503N04/5485517485/sizes/o/in/photostream/</a>).</p

Summary of selected animal JUNV and LASV vaccine trials.

1<p>Vaccinia virus has been used for human application.</p>2<p>Yellow fever virus 17D has been used for human application.</p>3<p>Virus used for challenge. Aim of the study was to explore the use of this method for vaccination against LASV infection.</p>4<p>Safety tests for attenuated <i>Salmonella typhimurium</i> expressing hepatitis B virus antigens have been done in human volunteers. JUNV, Junin virus; LASV, Lassa virus; LCMV, lymphocytic choriomeningitis virus; MOPV, Mopeia virus; TACV, Tacaribe virus.</p