Objective: To identify the possible virulence factors (VFs) of P. proliferus.
Methods: By Illumina HiSeq 4000 RNA-Seq platform, transcriptomes of adult P. proliferus
worms were sequenced to predict VFs via screening the homologues of traditional VFs of parasites
based on the annotations in the functional databases. Homology analysis was also performed to
screen homologous genes between P. proliferus and other four Paragonimus species (i.e., P.
kellicotti, P. skrjabini, P. miyazakii and P. westermani) whose transcriptomes were downloaded
from the National Center for Biotechnology Information (NCBI) database, and then the
differential-expressed homologous genes (DEHGs) were screened via comparisons of P. proliferus
and P. kellicotti, P. skrjabini, P. miyazakii and P. westermani, respectively. Finally, an overlap of
the predicted VFs and DEHGs was performed to identify possible key VFs that do not only belong
to the predicted VFs but also DEHGs.
Results: A total of 1,509 genes of P. proliferus homologous to traditional VFs, including surface
antigens (SAGs), secreted proteins (SPs), ATP-Binding Cassette (ABC) Transporters, actin-related
proteins (ARPs), aminopeptidases (APases), glycoproteins (GPs), cysteine proteases (CPs), and
heat shock proteins (HSPs), were identified. Meanwhile, homology analysis identified 6279
DEHGs among the five species, of which there were 48 DEHGs being mutually differentialexpressed
among the four pairs of comparisons, such as MRP, Tuba 3, PI3K, WASF2, ADK,
Nop56, DNAH1, PFK-2/FBPase2, Ppp1r7, SSP7. Furthermore, the overlap between the predicted
VFs and DEHGs showed 97 genes of the predicted VFs that simultaneously belonged to DEHGs.
Strikingly, of these 97 genes, only 26, including Chymotrypsin, Leucine APases, Cathepsin L, HSP
70, and so on, were higher expressed in P. proliferus while all the remaining were lower expressed
than in the four other species.
Conclusion: This work provides a fundamental context for further studies of the pathogenicity of
P. proliferus. Most of the predicted VFs which simultaneously belonged to DEHGs were lower
expressed in P. proliferus.