Three avian viral pathogens circulate in Germany with particular importance for animal disease surveillance due to their zoonotic potential, their impact on wild bird populations and/or poultry farms: Highly pathogenic (HP) avian influenza virus (AIV) of subtype H5 (HPAIV H5), Usutu virus (USUV), and West Nile virus (WNV). Whereas HPAIV H5 has been mainly related to epizootic outbreaks in winter, the arthropod-borne viruses USUV and WNV have been detected more frequently during summer months corresponding to peak mosquito activity. Since 2021, tendencies of a potentially year-round, i.e. enzootic, status of HPAIV in Germany have raised concerns that Orthomyxoviruses (AIV) and Flaviviruses (USUV, WNV) may not only circulate in the same region, but also at the same time and in the same avian host range. In search of a host species group suitable for a combined surveillance approach for all mentioned pathogens, we retrospectively screened and summarized case reports, mainly provided by the respective German National Reference Laboratories (NRLs) from 2006 to 2021. Our dataset revealed an overlap of reported infections among nine avian genera. We identified raptors as a particularly affected host group, as the genera Accipiter, Bubo, Buteo, Falco, and Strix represented five of the nine genera, and highlighted their role in passive surveillance. This study may provide a basis for broader, pan-European studies that could deepen our understanding of reservoir and vector species, as HPAIV, USUV, and WNV are expected to further become established and/or spread in Europe in the future and thus improved surveillance measures are of high importance.
Rifttalfieber ist eine durch Infektion mit dem Rifttalfiebervirus ausgelöste Zoonose. Die aktuell verfügbaren attenuierten Impfvirusstämme wie z.B. der MP12-Stamm verfügen über eine variable Restvirulenz. Die Hypothese dieser Arbeit ist, dass Empfänglichkeit, Organtropismus und Läsionsprofil nach Infektion mit dem MP12-Stamm durch verschiedene Signalwege des Immunsystems beeinflusst werden.
Three avian viral pathogens circulate in Germany with particular importance for animal disease surveillance due to their zoonotic potential, their impact on wild bird populations and/or poultry farms: Highly pathogenic (HP) avian influenza virus (AIV) of subtype H5 (HPAIV H5), Usutu virus (USUV), and West Nile virus (WNV). Whereas HPAIV H5 has been mainly related to epizootic outbreaks in winter, the arthropod-borne viruses USUV and WNV have been detected more frequently during summer months corresponding to peak mosquito activity. Since 2021, tendencies of a potentially year-round, i.e. enzootic, status of HPAIV in Germany have raised concerns that Orthomyxoviruses (AIV) and Flaviviruses (USUV, WNV) may not only circulate in the same region, but also at the same time and in the same avian host range. In search of a host species group suitable for a combined surveillance approach for all mentioned pathogens, we retrospectively screened and summarized case reports, mainly provided by the respective German National Reference Laboratories (NRLs) from 2006 to 2021. Our dataset revealed an overlap of reported infections among nine avian genera. We identified raptors as a particularly affected host group, as the genera Accipiter, Bubo, Buteo, Falco, and Strix represented five of the nine genera, and highlighted their role in passive surveillance. This study may provide a basis for broader, pan-European studies that could deepen our understanding of reservoir and vector species, as HPAIV, USUV, and WNV are expected to further become established and/or spread in Europe in the future and thus improved surveillance measures are of high importance.
Usutu virus (USUV) is an arthropod-borne (arbo), single-stranded RNA virus belonging to the Japanese encephalitis virus serogroup within the family Flaviviridae. After the initial detection of USUV in German mosquitoes in August 2010, the virus has spread in the last three years and caused epizootics among wild and captive birds in southwest Germany.
The phylogenetic analyses suggest that the epizootic USUV strain has most likely spread from Austria to Germany. So far, there is hardly a decline in the number of USUV infected wild birds in 2012 noticeable compared to the previous year. Interestingly, USUV seems to have hardly spread at all as infections were found only in areas where cases had already been found in 2011.
Overwintering of the USUV in the mosquitopopulation could be shown.
Although USUV is considered to have an only low zoonotic potential, public health authorities in Germany should be aware of the possibility of USUV infections also in humans.
Abstract The ancient cytokine interleukin 15-like (IL-15L) was lost in humans and mice but not throughout mammals. This is the first study to describe IL-15L functions, namely in the fish rainbow trout. Fish have only one α-chain receptor gene IL-15Rα , whereas in mammalian evolution this gene duplicated and evolved into IL-15Rα plus IL-2Rα . Trout IL-2, IL-15 and IL-15L all could bind IL-15Rα and were able to induce phosphorylation of transcription factor STAT5. Reminiscent of the mammalian situation, trout IL-15 was more dependent on “in trans ” presentation by IL-15Rα than IL-2. However, whereas trout IL-15 could also function as a free cytokine as known for mammalian IL-15, trout IL-15L function showed a total dependency on in trans presentation by IL-15Rα. Trout lymphocytes from the mucosal tissues gill and intestine were sensitive to IL-15, but refractory to IL-2 and IL-15L, which is reminiscent of sensitivities to IL-15 in mammals. Distinguishing engagement of the IL-2Rα/IL-15Rα receptor chain may explain why IL-2 and IL-15 were selected in evolution as major growth factors for regulatory T cells and lymphocytes in mucosal tissues, respectively. Trout IL-15L efficiently induced expression of IL-4 and IL-13 homologues in CD4 - CD8 - IgM - splenocytes, and we speculate that the responsive cells within that population were type 2 innate lymphoid cells (ILC2). In contrast, trout IL-15 efficiently induced expression of interferon γ and perforin in CD4 - CD8 - IgM - splenocytes, and we speculate that in this case the responsive cells were natural killer (NK) cells. In fish, in apparent absence of IL-25, IL-33 and TSLP, primitive IL-15L may have an important role early in the type 2 immunity cytokine cascade. Among trout thymocytes, only CD4 - CD8 - thymocytes were sensitive to IL-15L, and different than in mammals the CD4 + CD8 + thymocytes were quite sensitive to IL-2. In addition, the present study provides (i) the first molecular evidence for inter-species cytokine with receptor chain interaction across fish-mammal borders, and (ii) suggestive evidence for a tendency of IL-2/15/15L cytokines to form homodimers as an ancient family trait. This is the first comprehensive study on IL-2/15/15L functions in fish and it provides important insights into the evolution of this cytokine family.
