The present invention relates to immunogenic complexes formed between polyanionic carbomers and Env polypeptides. Uses of the immunogenic complexes in applications including inducing an immune response and immunization generally are described. Methods of forming and manufacture of the immunogenic complexes are also described. The present invention also relates to immunogenic compositions including low viscosity, polyanionic carbomers and Env polypeptides. Uses of such immunogenic compositions in applications including inducing an immune response and immunization generally are described. Methods of manufacture of such immunogenic compositions are also described.