Association of low serum TGF-β level in hantavirus infected patients with severe disease

Background: Hantaviruses are emerging zoonotic pathogens which cause hemorrhagic fever with renal syndrome, an immune-mediated pathogenesis is discussed. The aim of the present study was to investigate the role of TGF-β expression in acute hantavirus infection. Results: We retrospectively studied 77 patients hospitalised with acute Puumala infection during a hantavirus epidemic in Germany in 2012. Hantavirus infection was confirmed by positive anti-Puumala hantavirus IgG and IgM. Plasma levels of transforming growth factor (TGF)-β1 and TGF-β2 were analysed. Based on glomerular filtration rate on admission, patients were divided in mild and severe course of disease. Puumala virus RNA was detected by PCR amplification of the viral L segment gene. Out of 77 Puumala virus infected patients, 52 (68%) were male. A seasonal distribution was detected in our cohort with a peak in summer 2012, the highest incidence was observed in the age group of 30–39 years. Puumala virus RNA was detectable in 4/77 cases. Patients with severe disease had a significant longer hospital stay than patients with mild disease (6.2 vs 3.6 days). Thrombocyte count (186 vs 225 per nl), serum TGF-β1 (74 vs 118 ng/l) and TGF-β2 (479 vs 586 pg/l) were significantly lower in severe compared to mild disease. However, C-reactive protein (CRP) was significantly higher in patients with severe disease (62 vs 40 mg/l). TGF-β1/Cr was the most sensitive and specific marker associated with renal dysfunction. Conclusion: High serum CRP and low serum TGF-β in the early phase of hantavirus infection is associated with a severe course of disease. Our results support the hypothesis of an immune-mediated pathogenesis in hantavirus infection

Dobrava Hantavirus Infection Complicated by Panhypopituitarism, Istanbul, Turkey, 2010

We identified Dobrava-Belgrade virus infection in Turkey (from a strain related to hantavirus strains from nearby countries) in a patient who had severe symptoms leading to panhypopituitarism, but no known risk for hantavirus. Our findings emphasize the need for increased awareness of hantaviruses in the region and assessment of symptomatic persons without known risk factors for infection

Characterisation of the rat cytomegalovirus isolate "England"

Die beiden bislang im Wesentlichen untersuchten Isolate des Ratten- Cytomegalovirus (RCMV) sind RCMV-Maastricht (RCMV M) und RCMV-England (RCMV-E). Im Gegensatz zur veröffentlichten kompletten RCMV-M Sequenz wurden von RCMV-E bislang Sequenzen nur partiell publiziert. Aufgrund der Sequenzdaten und Unterschiede bezüglich ihrer Genomgröße und Restriktionsmuster wurde angenommen, dass es sich bei den beiden Isolaten um eigenständige Virusspezies handelt. Um dies zu bestätigen, wurden im Rahmen dieser Arbeit die Leserahmen des RCMV-E Genoms identifiziert und mit RCMV-M und dem murinen CMV (MCMV) verglichen. Sowohl im strukturellen Genomaufbau als auch in den kodierten Genen weisen die Viren deutliche Unterschiede auf. Der direkte Vergleich der Proteinsequenzen deutet auf eine nähere Verwandtschaft des RCMV-E zu MCMV als zu RCMV-M hin. Anhand ausgewählter konservierter Proteine wurden phylogenetische Analysen zur Eingruppierung des RCMV-E innerhalb der CMVs durchgeführt. Diese Analysen belegen, dass es sich bei den beiden Viren um distinkte Spezies handelt. Eine weitere Besonderheit des RCMV-E besteht darin, eine Reihe von Genen zu kodieren, die bislang nicht in anderen CMVs beschrieben wurden, zu welchen das RCMV C-Typ-Lektin-ähnliche Protein (RCTL) gehört. In dieser Arbeit wurde RCTL funktionell untersucht. Hierzu wurden zwei Rattenstämme mit RCMV-E Wildtypvirus und einer RCTL- Deletionsmutante infiziert. Es konnte gezeigt werden, dass RCTL an den inhibitorischen NK-Zell-Rezeptor NKR-P1B eines Rattenstammes bindet und die Funktion des NK-Zell-Liganden rClr-b substituiert. Durch diese Interaktion werden NK-Zellen nicht aktiviert und die infizierte Zelle vor NK-Zell- mediierter Lyse geschützt. Hingegen führt der Verlust von RCTL zu einer effizienten Eliminierung infizierter Zellen. Durch Depletion der NK-Zellen kann dieser Verlust des RCTL kompensiert werden und die Deletionsmutante ist wieder in der Lage, sich im Tier auszubreiten. In dem anderen Rattenstamm hat der Verlust von RCTL keinen Einfluss auf die Ausbreitung des Virus in der Ratte, so dass davon ausgegangen werden kann, dass nicht nur evolutionärer Druck auf das Virus ausgeübt wird, sich dem Immunsystem zu entziehen, sondern das Immunsystem auch einem Druck unterliegt, auf die Immunevasion des Erregers zu reagieren.The two preponderant isolates of rat cytomegalovirus (RCMV) are RCMV- Maastricht (RCMV-M) and RCMV-England (RCMV-E). In contrast to the completely published RCMV-M sequence only partial sequence data of RCMV-E are available. Based on this sequence data and differences in genome size and restriction patterns, it has been assumed that both isolates represent independent virus species. To verify this assumption, the open reading frames in RCMV-E were identified and compared to those in RCMV-M and murine CMV (MCMV). Differences among the viruses were observed in genome structure as well as in the encoded genes. Direct comparison of the protein sequences revealed a closer relationship between RCVM-E and MCMV than between RCMV-E and RCMV-M. Based on a subset of conserved proteins, a phylogenetic analysis was performed to classify the relationship of RCMV-E with other CMVs. This analysis proved that RCMV-M and RCMV-E represent distinct species. Another characteristic aspect of RCMV-E is that it encodes a couple of genes which have not been described in other CMVs. One of those genes is the RCMV C-type-lectin-like protein (RCTL). In this thesis, RCTL was functionally characterized. Therefore, two different rat strains were infected with RCMV-E wildtyp virus and a RCTL deletion mutant. It could be shown that RCTL binds to the inhibitory NK-cell receptor NKR-P1B in one rat strain and functions as a decoy-ligand for the host NK-cell ligand. By this interaction, NK-cell activation is silenced and the infected cells are protected from NK-cell mediated lysis. In contrast, the loss of RCTL results in an efficient elimination of the infected cells. By depleting the NK-cells, the loss of RCTL can be compensated in that particular rat strain and the virus is able to spread in the host. In the second rat strain, the loss of RCTL as no effect on virus spread. Hence, it can be assumed that there is not only an evolutionary pressure on the virus to evade the immune response but also on the immune system to counteract the pathogen- associated immune evasion mechanism

Cytomegalovirus Evasion of Innate Immunity by Subversion of the NKR-P1B:Clr-b Missing-Self Axis

SummaryCytomegaloviruses are known to encode several gene products that function to subvert MHC-dependent immune recognition. Here we characterize a rat cytomegalovirus (RCMV) C-type lectin-like (RCTL) gene product with homology to the Clr ligands for the NKR-P1 receptors. RCMV infection rapidly extinguished host Clr-b expression, thereby sensitizing infected cells to killing by natural killer (NK) cells. However, the RCTL protein functioned as a decoy ligand to protect infected cells from NK killing via direct interaction with the NKR-P1B inhibitory receptor. In vivo, an RCTL mutant virus displayed diminished virulence in an NK-dependent and strain-specific manner, suggesting that host NKR-P1 polymorphisms have evolved to avert the viral decoy mechanism while maintaining Clr-b recognition to preserve self tolerance. These findings reveal a unique strategy adopted by cytomegaloviruses to evade MHC-independent self-nonself discrimination. The existence of lectin-like genes in several poxviruses suggests that this may represent a common theme for viral evasion of innate immunity

Complete Genome Sequence of the English Isolate of Rat Cytomegalovirus (Murid Herpesvirus 8)

The complete genome of the English isolate of rat cytomegalovirus (RCMV-E) was determined. RCMV-E has a 202,946-bp genome with noninverting repeats but without terminal repeats. Thus, it differs significantly in size and genomic arrangement from closely related rodent cytomegaloviruses (CMVs). To account for the differences between the rat CMV isolates of Maastricht and England, RCMV-E was classified as Murid herpesvirus 8 by the International Committee on Taxonomy of Viruses

Multiple Synchronous Outbreaks of Puumala Virus, Germany, 2010

To investigate 2,017 cases of hantavirus disease in Germany, we compared 38 new patient-derived Puumala virus RNA sequences identified in 2010 with bank vole–derived small segment RNA sequences. The epidemic process was driven by outbreaks of 6 Puumala virus clades comprising strains of human and vole origin. Each clade corresponded to a different outbreak region