Genomic characterization of a novel human astrovirus MLB1 variant from Tanzania.

Human astroviruses (HAstV) are emerging viral pathogens responsible for gastroenteritis worldwide, but whole-genome data from Africa, including from Tanzania, remains scarce. A genomic analysis of stools of children with diarrhea was performed using nanopore sequencing. We successfully assembled HAstV-MLB1 complete genomes from two different stool samples, achieving high sequence coverage of 354.75x and 769.94x, respectively. Analyses included phylogeny, synteny, comparative genomics, and structural characterization of the capsid protein. The two Tanzanian HAstV-MLB1 strains showed high genetic similarity to each other and clustered within the Melbourne-like virus (MLB1) clade and were most closely related (96% similarity) to the Australian reference strain. Both synteny and capsid structure analysis confirmed their conserved nature. This study presents the first whole-genome data from Tanzania. Our findings align with the previously reported genetic stability of HAstV, regional variability, and potential functional variation of the capsid protein, emphasizing the need for surveillance and functional characterization.