The present invention relates to a Lactuca sativa L. var. longifolia Lam seed designated as 41-52 RZ, referred to as Nirvanus, which exhibits resistance against downy mildew (Bremia lactucae Regel), currant-lettuce aphid (Nasonovia ribis-nigri), corky root (Sphingomonas suberifaciens) and lettuce mosaic virus (LMV), the representative seed having been deposited with the National Collections of Industrial, Marine and Food Bacteria (NCIMB) in Bucksburn, Aberdeen AB21 9YA, Scotland, UK and assigned NCIMB Acession No. 41326. The present invention also relates to a Lactuca sativa L. var. longifolia Lam plant produced by growing the 41-52 RZ (Nirvanus) seed. The invention further relates to methods for producing the lettuce cultivar, represented by lettuce variety 41-52 RZ.