Microbiota dynamics during Ascaris suum larval migration: Implications for host microbial communities in a murine model

The complex interactions between parasites, their hosts, and associated microbiota hold significant implications for host health and disease outcomes. Helminths like Ascaris lumbricoides and Ascaris suum can significantly alter the host's intestinal microbiota, affecting both parasite biology and host pathology. Despite extensive research on host-microbiota changes due to helminth infections, the study of helminth-associated microbiota remains limited. This study aims to characterize the microbiota associated with Ascaris larvae and surrounding host tissues at distinct developmental stages (day 4, day 8, day 14), during larval migration through the liver, lungs, and intestine, and its impact on the host's microbiota in a murine model. Twenty mice were infected with 2500 embryonated A. suum eggs via oral gavage. Five Ascaris-infected mice and age-matched naïve mice were euthanized at 4-, 8-, and 14-days post-infection (DPI). Stool, intestine, liver, and lung samples were collected. Larvae were isolated from embryonated eggs in vitro, from the liver at 4 DPI, and the lung at 8 DPI. Utilizing 16S rRNA sequencing, we analyzed bacterial diversity in samples from different Ascaris stages and host tissues. Our results revealed a total of 8040 amplicon sequence variants (ASVs) with Ascaris samples displaying the highest diversity. Notably, Ascaris-larvae associated microbiota differed significantly from that of the host, with higher diversity observed in the parasite. Differential abundance analysis identified distinct taxonomic patterns, highlighting specific genera such as Bradyrhizobium, Achromobacter, and Pseudomonas in Ascaris. Our findings suggest that Ascaris harbors a unique microbiota that potentially exchanges bacteria with the host during larval migration. These insights pave the way for further research into the ecological and functional dynamics of helminth-microbiota interactions, which may inform novel therapeutic strategies targeting these microbial relationships to mitigate helminth infections and improve host health outcomes.