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. 2015 Feb 18;33(8):977–984. doi: 10.1016/j.vaccine.2015.01.028

Fig. 3.

Fig. 3

A panel of cell lines bearing chimaeric human × feline CD134 molecules was used to assess receptor usage by 12 pseudotypes bearing Envs from cat SV1. CD134 consists of 3 CRDs; HHH represents MCC cells expressing the entire human CD134, while CLL-CD134 represents cells expressing the entire feline CD134. These constructs served as negative and positive controls, respectively. FFF represents MCC cells expressing feline CD134 while FFH represents MCC cells expressing a chimeric feline/human CD134 with the CRD2 domain comprising the human sequence. These cells are permissible for entry of prototypic “late” isolates of FIV such as B2542 [44] which are CRD2 independent. Pseudotypes bearing GL8 and B2542 Envs were tested in parallel as representative “early” and “late” pseudotypes, respectively. Each bar represents mean luciferase activity (cpm) ± standard error (n = 3). The luciferase activity of pseudotypes on MCC cells expressing the CD134 chimaera containing the human CRD2 domain (FFH; grey bars) determined the subsequent pseudotype classification. All of the pseudotypes bearing SV1 Envs shared similar phenotypes with the pseudotypes bearing the Env of the “early”, CRD2-dependent GL8 strain.