Stage and tissue expression patterns of Schistosoma mansoni venom allergen-like proteins SmVAL 4, 13, 16 and 24

Abstract

Background Schistosoma mansoni venom allergen-like protein (SmVAL) is a gene family composed of 29 members divided into group 1 encoding proteins potentially secreted, and group 2 encoding intracellular components. Some members were found to be upregulated in the transition of germ ball - cercariae - day 3 schistosomula, suggesting that group 1 SmVAL proteins are associated with the invasion of the human host, although their functions are not completely established. Recently, we have described the localization of SmVAL7 (group 1) and SmVAL6 (group 2) transcripts in the oesophageal gland and in the oral and ventral suckers of adult parasites, respectively. The expression patterns of the two genes suggest that SmVAL7 protein plays a role in the blood-feeding process while SmVAL6 is associated with the parasite attachment and movement in the vasculature. In this way, searching for additional secreted SmVAL proteins that could be involved in key processes from skin penetration to the beginning of blood-feeding, we investigated the tissue localization of SmVAL4, 13, 16 and 24 by whole-mount in situ hybridization (WISH).ResultsWe report here the localization of group 1 SmVAL4 and 24 transcripts in the pre-acetabular glands of developing germ balls. Time course experiments of in vitro cultured schistosomula after cercariae transformation demonstrated that SmVAL4 protein is secreted during the first 3 h of in vitro culture, correlating with the emptying of acetabular glands as documented by confocal microscopy. In addition, the localization of SmVAL13 transcripts in adult male anterior oesophageal gland suggests that the respective protein may be involved in the first steps of the blood-feeding process. SmVAL16 was localized close to the neural ganglia and requires further investigation.ConclusionsOur findings demonstrate that SmVAL proteins have localizations that place them in strategic positions to be considered as potential vaccine candidates as some members are exposed to interaction with the immune system and may participate in key processes of mammalian invasion and parasitism establishment.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-017-2144-2) contains supplementary material, which is available to authorized users.

Meta-analysis of RNA-seq studies reveals genes responsible for life stage-dominant functions in Schistosoma mansoni

“…In addition, we supported the discovery of SmVAL22 preferential expression in sporocyst ). SmVAL1 and SmVAL24 were found to be nearly exclusively in cercaria, which differs from the finding about higher SmVAL24 expression in the germ balls (Fernandes et al 2017). More interestingly, we discovered two VALs that seem exclusive for the testis, whose functions need further investigations.…”

Schistosoma mansoni venom allergen-like proteins: phylogenetic relationships, stage-specific transcription and tissue localization as predictors of immunological cross-reactivity

“…Despite the abundance of group 1 SmVALs in these important life stages, the understanding of SmVAL function remains somewhat limited. A lipid-binding function was demonstrated for SmVAL4 (Kelleher et al, 2014), a plasminogen-binding function was revealed for SmVAL18 (Fernandes et al, 2017) and a host matrix metalloprotease modulatory function detected for SmVAL9 (Yoshino et al, 2014). The group 2 protein SmVAL6 has recently been shown to be a target for IgE, IgG4 and IgG1 responses in infected individuals, indicating that the SmVALs may influence the immune response (Farnell et al, 2015).…”

“…Schistosoma mansoni cercariae, schistosomula, adult worms, eggs, miracidia and mother sporocysts (24 h and 96 h sporocysts) were obtained as previously described (Chalmers et al, 2008). Germ balls were obtained as previously described (Fernandes et al, 2017).…”

Dirofilaria immitis Could Be a Risk Factor for the Development of Allergic Diseases in Humans

“…It has been described that parasite infections can develop a strong response and high levels of IgE in allergic sufferers, i.e., asthma or tropical pulmonary eosinophilia [ 28 , 29 , 30 , 31 ]. Moreover, it seems that infections by A. lumbricoides, T. canis, T. trichiura , hookworm, and S. mansoni can cause allergic reactions in humans [ 15 , 16 , 17 , 18 , 19 ]. This has also been described for different types of human filariasis [ 32 ] and specifically regarding heartworm, there is some evidence that indicates that this parasite might also have the same capacity [ 21 , 33 ].…”

“…Studies have shown the role of some helminth parasites in the development of allergic processes in humans, and have shown associations between allergic sensitization (i.e., to mites) and seropositivity to parasites, such as Ascaris lumbricoides , Toxocara canis, Trichuris trichiura , hookworm, and Schistosoma mansoni [ 15 , 16 , 17 , 18 , 19 ]. Furthermore, there is evidence that some filariae, such as D. immitis , may influence the development of hypersensitivity in people [ 20 , 21 ].…”