Lentiviral vectors pseudotyped with influenza surface glycoproteins represent an alternative to wild type virus for serological assays. The influenza neuraminidase (NA) has the ability to bud and release new virions with or without the contribution of Haemagglutinin (HA). Influenza pseudotypes expressing NA alone, or with HA, can be produced to evaluate the antibody response against NA using an enzyme-linked lectin assay (ELLA). The expression of an avian HA with human NAs has enabled the detection of specific antibody reponses against the human circulating subtypes of NA. This protocol describes the efficient production of NA pseudotypes for these ELLA assays. The pseudotypes have H11 HA on the surface as this will not react with human sera.Figure 1. Cartoon schematic of lentiviral vectors pseudotyped with NA or HA+NA for use in ELLA assays.