PRH1 and infection: Moreover, after the immunization with CCFkH5- and CCAnH7-VLP vaccines, the subsequent challenge infection with A/Puerto Rico/8/34 (H1N1; PRH1), RG-A/Barn Swallow/Hong Kong/1161/2010-A/PR/8/34 H5N1 [R] (6 + 2) (HKH5), and RG-A/Anhui/2013-A/PR/8/34 H7N9 [R] (6 + 2) (AnH7) viruses triggered the production of homologous HI antibody, showing 1,024 to PRH1, 256 to HKH5, and 1,024 to AnH7 viruses.