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

<i>Biomphalaria straminea</i> (Gastropoda: Planorbidae) and <i>Physa acuta</i> (Gastropoda: Physidae), both invasive species in southern China, are important vectors for zoonotic diseases. However, the lack of information on the infection dynamics of <i>Angiostrongylus cantonensis</i> in these snails leaves gaps in understanding the compatibility mechanisms between the snails and the parasite. This study aims to reveal differences in <i>A. cantonensis</i> infection between <i>B. straminea</i> and <i>P. acuta</i> from Guangdong, southern China, and to investigate the potential interaction mechanisms between <i>A. cantonensis</i> and <i>P. acuta</i>. We found that both phenotypic color variants of <i>B. straminea</i> snails were highly susceptible to <i>A. cantonensis</i> (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, <i>B. straminea</i> is more suitable than <i>P. acuta</i> for establishing the life cycle of <i>A. cantonensis</i> in the laboratory. In contrast, geographic isolates of <i>P. acuta</i> exhibited variable susceptibility (13-91%) and markedly lower parasite loads, with 6-32 third-stage larvae per snail. Diverse strains of <i>P. acuta</i> exhibit distinct immune responses to <i>A. cantonensis</i>, 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 <i>B. straminea</i> as both a high-risk vector and a laboratory model for studying the life cycle of <i>A. cantonensis</i>, while highlighting <i>P. acuta</i> as a model for investigating parasite-snail interactions, thereby enhancing our understanding of snail-parasite dynamics in southern China.