Marburg virus (MARV) induces severe hemorrhagic fever in humans and nonhuman primates but only transient nonlethal disease in rodents. However, sequential passages of MARV in rodents boosts infection leading to lethal disease. Guinea pig-adapted MARV contains one mutation in the viral matrix protein VP40 at position 184 (VP40 D184N ). The contribution of the D184N mutation to the efficacy of replication in a new host is unknown. In the present study, we demonstrated that recombinant MARV containing the D184N mutation in VP40 [rMARV VP40(D184N) ] grew to higher titers than wild-type recombinant MARV (rMARV WT ) in guinea pig cells. Moreover, rMARV VP40(D184N) displayed higher infectivity in guinea pig cells. Comparative analysis of VP40 functions indicated that neither the interferon (IFN)-antagonistic function nor the membrane binding capabilities of VP40 were affected by the D184N mutation. However, the production of VP40-induced virus-like particles (VLPs) and the recruitment of other viral proteins to the budding site was improved by the D184N mutation in guinea pig cells, which resulted in the higher infectivity of VP40 D184N -induced infectious VLPs (iVLPs) compared to that of VP40-induced iVLPs. In addition, the function of VP40 in suppressing viral RNA synthesis was influenced by the D184N mutation specifically in guinea pig cells, thus allowing greater rates of transcription and replication. Our results showed that the improved viral fitness of rMARV VP40(D184N) in guinea pig cells was due to the better viral assembly function of VP40 D184N and its lower inhibitory effect on viral transcription and replication rather than modulation of the VP40-mediated suppression of IFN signaling. IMPORTANCEThe increased virulence achieved by virus passaging in a new host was accompanied by mutations in the viral genome. Analyzing how these mutations affect the functions of viral proteins and the ability of the virus to grow within new host cells helps in the understanding of the molecular mechanisms increasing virulence. Using a reverse genetics approach, we demonstrated that a single mutation in MARV VP40 detected in a guinea pig-adapted MARV provided a replicative advantage of rMARV VP40(D184N) in guinea pig cells. Our studies show that this replicative advantage of rMARV VP40 D184N was based on the improved functions of VP40 in iVLP assembly and in the regulation of transcription and replication rather than on the ability of VP40 to combat the host innate immunity. F iloviruses, including Ebolaviruses (EBOV) and Marburg virus (MARV), are enveloped, nonsegmented, negative-strand RNA viruses (1). These viruses are known to cause severe fevers in humans and nonhuman primates, with case fatality rates of up to 90% (2). Although several antivirals and vaccines currently are being tested in clinical studies, none of them are licensed for human use. Therefore, work with filoviruses is restricted to biosafety level 4 (BSL-4) facilities. The recent EBOV outbreak in Guinea, Sierra Leone, and Liberia demonstrated the ...

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Zusammenfassung In diesem Jahr lockte die RETTmobil ? die Internationale Leitmesse f?r Rettung und Mobilit?t ? zum 15. Mal zahlreiche Besucher nach Fulda. Mit 23?248 Interessierten waren es etwas weniger als im Vorjahr, insgesamt waren aber alle Beteiligten sehr zufrieden mit dem kleinen Jubil?um.