Uncovering Flavivirus Host Dependency Factors through a Genome-Wide Gain-of-Function Screen
Authors: Petrova, Evgeniya; Gracias, Segolene; Beauclair, Guillaume; Tangy, Frederic; Jouvenet, Nolwenn
Flaviviruses, such as dengue (DENV), West Nile (WNV), yellow fever (YFV) and Zika (ZIKV) viruses, are mosquito-borne pathogens that present a major risk to global public health. To identify host factors that promote flavivirus replication, we performed a genome-wide gain-of-function cDNA screen for human genes that enhance the replication of flavivirus reporter particles in human cells. The screen recovered seventeen potential host proteins that promote viral replication, including the previously known dolichyl-diphosphooligosaccharide--protein glycosyltransferase non-catalytic subunit (DDOST). Using silencing approaches, we validated the role of four candidates in YFV and WNV replication: ribosomal protein L19 (RPL19), ribosomal protein S3 (RPS3), DDOST and importin 9 (IPO9). Applying a panel of virological, biochemical and microscopic methods, we validated further the role of RPL19 and DDOST as host factors required for optimal replication of YFV, WNV and ZIKV. The genome-wide gain-of-function screen is thus a valid approach to advance our understanding of flavivirus replication.
Infestation of small seabirds by Ornithodoros maritimus yticks: Effects on chick body condition, reproduction and associated infectious agents
TICKS AND TICK-BORNE DISEASES
Authors: Sanz-Aguilar, Ana; Payo-Payo, Ana; Rotger, Andreu; Yousfi, Lena; Moutailler, Sara; Beck, Cecile; Dumarest, Marine; Manuel Igual, Jose; Angel Miranda, Miguel; Vinas Torres, Mariana; Picorelli, Virginia; Gamble, Amandine; Boulinier, Thierry
Ticks can negatively affect their host by direct effects as blood feeding causing anaemia or discomfort, or by pathogen transmission. Consequently, ticks can have an important role in the population dynamics of their hosts. However, specific studies on the demographic effects of tick infestation on seabirds are still scarce. Seabird ticks have also the potential to be responsible for the circulation of little known tick-borne agents, which could have implications for non-seabird species. Here, we report the results of investigations on potential associations between soft tick Ornithodoros maritimus load and reproductive parameters of storm petrels Hydrobates pelagicus breeding in a large colony in a cave of Espartar Island, in the Balearic archipelago. We also investigated by molecular analyses the potential viral and bacterial pathogens associated with O. maritimus ticks present at the colony. Lower nestling survival was recorded in the most infested area, deep in the cave, compared to the area near the entrance. The parasite load was negatively associated with the body condition of the nestlings. One pool of ticks tested positive for West Nile virus and 4 pools tested positive for a Borrelia species which was determined by targeted nested PCR to have a 99% sequence identity with B. turicatae, a relapsing fever Borrelia. Overall, these results show that further investigations are needed to better understand the ecology and epidemiology of the interactions between ticks, pathogens and Procellariiform species.