Background
Schistosome parasites lay up to a thousand eggs per day inside the veins of their mammalian hosts. The immature eggs deposited by females against endothelia of venules will embryonate within days. Approximately 30% of the eggs will migrate to the lumen of the intestine to continue the parasite life-cycle. Many eggs, however, are trapped in the liver and intestine causing the main pathology associated with schistosomiasis mansoni and japonica, the liver granulomatous response. Excretory-secretory egg proteins drive much of egg-induced pathogenesis of schistosomiasis mansoni, and
Schistosoma japonicum
induce a markedly distinct granulomatous response to that of
S. mansoni
.
Methods
To explore the basis of variations in this responsiveness, we investigated the proteome of eggs of
S. japonicum
. Using mass spectrometry qualitative and quantitative (SWATH) analyses, we describe the protein composition of
S. japonicum
eggs secretory proteins (ESP), and the differential expression of proteins by fully mature and immature eggs, isolated from faeces and
ex vivo
adults.
Results
Of 957 egg-related proteins identified, 95 were exclusively found in
S. japonicum
ESP which imply that they are accessible to host immune system effector elements. An
in-silico
analysis implies that ESP are able of stimulating the innate and adaptive immune system through several different pathways. While quantitative SWATH analysis revealed 124 proteins that are differentially expressed by mature and immature
S. japonicum
eggs, illuminating some important aspects of eggs biology and infection, we also show that mature eggs are more likely than immature eggs to stimulate host immune responses.
Conclusions
Here we present a list of potential targets that can be used to develop better strategies to avoid severe morbidity during
S. japonicum
infection, as well as improving diagnosis, treatment and control of schistosomiasis japonica.
Electronic supplementary material
The online version of this article (10.1186/s13071-019-3403-1) contains supplementary material, which is available to authorized users.