Paper of the Month September 2015
Hemagglutinin-stem nanoparticles generate heterosubtypic influenza protection.
Nature Medicine 21, 1065–1070 (2015) doi:10.1038/nm.3927
Yassine HM, Boyington JC, McTamney PM, Wei CJ, Kanekiyo M, Kong WP, Gallagher JR, Wang L, Zhang Y, Joyce MG, Lingwood D, Moin SM, Andersen H, Okuno Y, Rao SS, Harris AK, Kwong PD, Mascola JR, Nabel GJ, Graham BS.
The antibody response to influenza is primarily focused on the head region of the hemagglutinin (HA) glycoprotein, which in turn undergoes antigenic drift, thus necessitating annual updates of influenza vaccines. In contrast, the immunogenically subdominant stem region of HA is highly conserved and recognized by antibodies capable of binding multiple HA subtypes1, 2, 3, 4, 5, 6. Here we report the structure-based development of an H1 HA stem–only immunogen that confers heterosubtypic protection in mice and ferrets. Six iterative cycles of structure-based design (Gen1–Gen6) yielded successive H1 HA stabilized-stem (HA–SS) immunogens that lack the immunodominant head domain. Antigenic characterization, determination of two HA–SS crystal structures in complex with stem-specific monoclonal antibodies and cryo-electron microscopy analysis of HA–SS on ferritin nanoparticles (H1–SS–np) confirmed the preservation of key structural elements. Vaccination of mice and ferrets with H1–SS–np elicited broadly cross-reactive antibodies that completely protected mice and partially protected ferrets against lethal heterosubtypic H5N1 influenza virus challenge despite the absence of detectable H5N1 neutralizing activity in vitro. Passive transfer of immunoglobulin from H1–SS–np–immunized mice to naive mice conferred protection against H5N1 challenge, indicating that vaccine-elicited HA stem–specific antibodies can protect against diverse group 1 influenza strains.
A stable trimeric influenza hemagglutinin stem as a broadly protective immunogen.
Science. 2015 Sep 18;349(6254):1301-6. doi: 10.1126/science.aac7263. Epub 2015 Aug 24.
Impagliazzo A, Milder F, Kuipers H, Wagner MV, Zhu X, Hoffman RM, van Meersbergen R, Huizingh J, Wanningen P, Verspuij J, de Man M, Ding Z, Apetri A, Kükrer B, Sneekes-Vriese E, Tomkiewicz D, Laursen NS, Lee PS, Zakrzewska A, Dekking L, Tolboom J, Tettero L, van Meerten S, Yu W, Koudstaal W, Goudsmit J, Ward AB, Meijberg W, Wilson IA, Radošević K.
The identification of human broadly neutralizing antibodies (bnAbs) targeting the hemagglutinin (HA) stem revitalized hopes of developing a universal influenza vaccine. Using a rational design and library approach, we engineered stable HA stem antigens ("mini-HAs") based on an H1 subtype sequence. Our most advanced candidate exhibits structural and bnAb binding properties comparable to those of full-length HA, completely protects mice in lethal heterologous and heterosubtypic challenge models, and reduces fever after sublethal challenge in cynomolgus monkeys. Antibodies elicited by this mini-HA in mice and nonhuman primates bound a wide range of HAs, competed with human bnAbs for HA stem binding, neutralized H5N1 viruses, and mediated antibody-dependent effector activity. These results represent a proof of concept for the design of HA stem mimics that elicit bnAbs against influenza A group 1 viruses.