Global gene expression analysis in skin biopsies of European red deer experimentally infected with bluetongue virus serotypes 1 and 8

Genomics reveal local skin immune response key to control sarcoptic mange in Iberian ibex (Capra pyrenaica)

BACKGROUND

Sarcoptic mange is an emerging and neglected contagious skin disease caused by the mite Sarcoptes scabiei, affecting humans, domestic animals, and wildlife. Mange is the main disease and a major concern for the management and conservation of populations of Iberian ibex (Capra pyrenaica), a medium-sized mountain ungulate endemic to the Iberian Peninsula and Northern Pyrenees. Differences in host-parasite interaction and host immune response determine mange clinical outcome, but little is known about the related differences in gene expression. This study determined blood and skin gene expressions in S. scabiei-experimentally infested Iberian ibexes.

RESULTS

Infestation with S. scabiei promoted immune and inflammatory genomic responses both in skin and blood, with two different clinical outcomes: either severe infestation or recovery. Sarcoptes scabiei induced local skin immunosuppression to favour its multiplication and establishment of the infestation in the host. Skin gene expression was mostly inflammatory and inefficient to control mange in the severely infected ibexes. Conversely, the immune skin response of the recovered ibexes effectively recognised S. scabiei and activated T-cells, limiting the infestation. Consequently, inflammation-related genes were more expressed in the blood of the severely infested ibexes than in those that recovered.

CONCLUSIONS

The results demonstrate that skin local cellular immune response is key to control sarcoptic mange and prevent the systemic spread of the disease and the associated inflammatory response. These results will be useful to understand the pathogenesis and drivers of the differential outcome of mange at individual scale, and the population and ecological consequences of such variability in Iberian ibex, as well as in other wildlife species, domestic animals, and humans.

Apoptosis versus survival of African horse sickness virus serotype 4-infected horse peripheral blood mononuclear cells

Expanding on our previous work, this study used transcriptome analysis of RNA sequences to investigate the various factors that contributed to either inducing apoptosis that resulted in cell death or promoting the survival of African horse sickness virus serotype 4 (AHSV4)-infected horse peripheral blood mononuclear cells (PBMC) after 24 h. Apoptosis is a host defense mechanism that prevents virus replication, accumulation and spread of progeny viruses. AHSV4-infected PBMC were killed via the intrinsic and the perforin/granzyme pathways of apoptosis during the attenuated AHSV4 (attAHSV4) in vivo primary and secondary immune responses. Trained innate immunity played an important role in circumventing viral interference that resulted in the elimination of AHSV4-infected PBMC through the intrinsic and the extrinsic pathways of apoptosis during the virulent AHSV4 (virAHSV4) in vitro secondary immune response. Oxidative stress in conjunction with IRE1α pro-apoptotic signaling played a major role in the induction of the intrinsic pathway of apoptosis and cytotoxic lymphocytes induced the perforin/granzyme or extrinsic pathways of apoptosis. In contrast, AHSV4-infected PBMC survived during the virAHSV4 in vitro primary immune response, which allows unrestrained viral replication. The virAHSV4 interference with the innate immune response resulted in impaired NK cell responses and delayed immune responses, which together with the antioxidant defense system promoted AHSV4-infected PBMC survival.

The role of wildlife in bluetongue virus maintenance in Europe: lessons learned after the natural infection in Spain

Bluetongue (BT) is a re-emergent vector-borne viral disease of domestic and wild ruminants caused by bluetongue virus (BTV), a member of the genus Orbivirus. A complex multi-host, multi-vector and multi-pathogen (26 serotypes) transmission and maintenance network has recently emerged in Europe, and wild ruminants are regarded as an important node in this network. This review analyses the reservoir role of wild ruminants in Europe, identifying gaps in knowledge and proposing actions. Wild ruminant species are indicators of BTV circulation. Excepting the mouflon (Ovis aries musimon), European wild ungulates do not develop clinical disease. Diagnostic techniques used in wildlife do not differ from those used in domestic ruminants provided they are validated. Demographic, behavioural and physiological traits of wild hosts modulate their relationship with BTV vectors and with the virus itself. While BTV has been eradicated from central and northern Europe, it is still circulating in the Mediterranean Basin. We propose that currently two BTV cycles coexist in certain regions of the Mediterranean Basin, a wild one largely driven by deer of the subfamily Cervinae and a domestic one. These are probably linked through shared Culicoides vectors of several species. We suggest that wildlife might be contributing to this situation through vector maintenance and virus maintenance. Additionally, differences in temperature and other environmental factors add complexity to the Mediterranean habitats as compared to central and northern European ones. Intervention options in wildlife populations are limited. There is a need to know the role of wildlife in maintaining Culicoides populations, and to know which Culicoides species mediate the wildlife-livestock-BTV transmission events. There is also a clear need to study more in depth the links between Cervinae deer densities, environmental factors and BTV maintenance. Regarding disease control, we suggest that research efforts should be focused on wildlife population and wildlife disease monitoring.