دانلود رایگان مقاله انگلیسی اولین ویژگی ویروس های منتقل شده از حلزون های آب شیرین بیومفالاریا - الزویر 2017

Abstract:

We report the genome sequence and organization of five viruses infecting snails of both Biomphalaria glabrata and Biomphalaria pfeifferi, which are vectors of the intestinal schistosomiasis. Four viruses presented a polyadenylated positive single strand RNA genome encoding one or two large open reading frames (ORFs) flanked by untranslated region. Conserved protein motifs typical of the picorna-like virus superfamily were identified in these viruses but they all presented different genome organization. Phylogenetic analysis confirmed their assignment to this superfamily. The partially characterized fifth virus presented sequence similarity for Totiviridae, a family of non-polyadenylated double-strand RNA viruses. Virus distribution and relative abundance between the five strains of Biomphalaria originating from different geographical areas was determined. Our results provide valuable information of new viruses from Biomphalaria and pave the way for future studies dedicated to their impact on snail fitness and Biomphalaria/Schistosoma interactions.

4. Conclusion

In this study, we report the identification and characterization of viruses from five Biomphalaria snail strains from RNAseq data. We discovered the presence of at least 5 new RNA viruses in both B. glabrata and B. pfeifferi species. The analysis of their sequence and genome organization revealed that four viruses were associated with the picorna-like virus superfamily, while the fifth one is close to the Totiviridae family. These results are supported by a phylogenetic analysis based on the RdRP and helicase protein sequences. The distribution analysis showed that BV1 was present in all the 5 snail strains while the four others were not equally distributed. Some of them, such as BV2 and BV3, seem to have a geographic-specific origin while others, such as BV4 and BV5, might be species-specific as they were only recovered from B. pfeifferi. BV1 is clearly the most abundant virus in B. glabrata, while it is BV4 in B. pfeifferi.

This work is a first step towards the identification of natural biological agents able to infect several populations of Biomphalaria, which is the intermediate host of the parasite S. mansoni. Future work will investigate viral prevalence at individual level, but also in field populations. The viral tropism, as well as the mode of transmission, has to be studied to better understand the different steps of the contamination process. The role played by these viruses on snail homeostasis also has to be investigated and more particularly during S. mansoni parasite infection to know if the presence of these viruses would be adaptive for the host.