Dynamics of Angiostrongylus cantonensis infection in invasive snails Biomphalaria straminea and Physa acuta from Guangdong, southern China

Abstract

Biomphalaria straminea (Gastropoda: Planorbidae) and Physa acuta (Gastropoda: Physidae), both invasive species in southern China, are important vectors for zoonotic diseases. However, the lack of information on the infection dynamics of Angiostrongylus cantonensis in these snails leaves gaps in understanding the compatibility mechanisms between the snails and the parasite. This study aims to reveal differences in A. cantonensis infection between B. straminea and P. acuta from Guangdong, southern China, and to investigate the potential interaction mechanisms between A. cantonensis and P. acuta. We found that both phenotypic color variants of B. straminea snails were highly susceptible to A. cantonensis (100%). The load of the L3 larvae ranged from 243 to 765 per snail, and it was positively correlated with the infection dosage. Based on the comparison of third-stage larvae quantities, B. straminea is more suitable than P. acuta for establishing the life cycle of A. cantonensis in the laboratory. In contrast, geographic isolates of P. acuta exhibited variable susceptibility (13-91%) and markedly lower parasite loads, with 6-32 third-stage larvae per snail. Diverse strains of P. acuta exhibit distinct immune responses to A. cantonensis, characterized by varied expression patterns of immune-related genes such as TEP1, HSP70, FREP2, Cu-Zn_SOD1, Fe-Mn_SOD2, MIF and Galectin. Our findings establish B. straminea as both a high-risk vector and a laboratory model for studying the life cycle of A. cantonensis, while highlighting P. acuta as a model for investigating parasite-snail interactions, thereby enhancing our understanding of snail-parasite dynamics in southern China.

Keywords: Angiostrongylus cantonensis; Biomphalaria straminea; Physa acuta; intermediate host; susceptibility.