A substantial number of sORF candidates were expressed under infection-related conditions, namely when Salmonella was grown under an invasion gene-inducing condition (referred to as ‘SPI-1’ condition or late exponential phase; exemplified by STsORF62; 47 aa), or in minimal medium mimicking the intravacuolar environment (‘SPI-2 low Mg2+’; e.g. STsORF37; 18 aa) (Fig. S2b). Here, SPI1 is linked to infection.