Molecular-level mapping of the human antibody response to hantavirus infection

As highlighted by the current global pandemic, an ability to respond rapidly to newly emerging pathogenic viral species that cross into the human population is essential for global health. A rapid response is greatly dependent upon prior knowledge of the antigenic regions presented on the surface of virally encoded glycoproteins and how they are targeted by neutralising antibodies during infection.

Upon transmission from small rodents to humans, hantaviruses cause severe disease, including hantavirus pulmonary syndrome and haemorrhagic fever with renal syndrome. The paucity of preventative vaccines and effective treatments, renders this globally distributed group of emerging viruses a persistent burden upon human health.

This proposal aims to reveal how the human immune response reacts to hantavirus infection. We will provide molecular-level detail for how neutralising antibodies, which are key for recovery and protecting against infection, target and impede the functionality of hantavirus surface-displayed glycoproteins. As this information is essential for the rational development of anti-hantavirus countermeasures, the information gleaned from this study will be essential for anti-viral and vaccine design efforts, improving our ability to respond to the emergences of these pathogens.

In our project, we will isolate neutralising and cross-neutralising antibodies (nAbs and crnAbs) from individuals previously infected with Puumala virus. We will adopt a multi-disciplinary structural (X-ray crystallography and cryo-electron tomography) and functional biology approach to determine how nAbs and crnAbs elicited during natural infection are able to prevent virus infection. This project will address four basic and translational biomedical questions:

1. Is one of the two glycoproteins displayed on the hantavirus surface, Gn or Gc, targeted more efficiently by nAbs following hantavirus infection?
2. Can we identify sites of vulnerability on Gn or Gc that are conserved amongst genetically distinct and biomedically relevant hantaviruses?
3. What are the mechanism(s) of action utilised by potent hantaviral nAbs and crnAbs generated in this project and at what stage of host-cell entry do they impede?
4. Can we identify synergistic combinations of human nAbs and crnAbs that can prevent hantavirus infection?

By understanding the molecular and mechanistic basis of the human antibody-mediated neutralisation to hantavirus infection, this research will improve our readiness for the emergence of new and established hantaviruses by: (i) providing new insights into the biology of these important pathogens, and (ii) providing a blueprint that will empower the development of anti-hantavirus biologics, including synergistic antibody cocktails for use in disease treatment and pan-hantavirus vaccine candidates.

The transmission of pathogenic hantaviruses from small animals to humans can cause severe disease with mortality rates of up to 40%. Critically, there are currently no approved vaccines or therapeutics for the prevention or treatment of hantavirus infection. Although production of neutralising antibodies (nAbs) that target the hantavirus surface glycoproteins is essential for disease clearance and protection, little is known about the epitopes targeted by nAbs, nor their mechanism of action. Building upon the technologies developed in our previous MRC-funded research, we will isolate nAbs and cross-neutralising Abs (crnAbs) from the acute and convalescent phases of hantavirus infection in humans. Combining functional and state-of-the-art structural approaches, including X-ray crystallography and cryo-electron tomography, we will;
(i) Define the relative contribution of human nAbs against the two hantaviral glycoproteins, Gn and Gc.
(ii) Identify singly and cross-reactive epitopes on the hantavirus surface that are targeted by nAbs and crnAbs, respectively.
(iii) Provide structure-based insights into immune recognition by nAbs and crnAbs.
(iv) Define the mechanism(s) of action utilised by potent hantaviral nAbs and crnAbs.
The molecular-level information delivered by this research will augment ongoing efforts to detect hantaviruses in the field and rationally develop antibody-based immunotherapeutics and therapeutics capable of preventing hantavirus infection. Furthermore, this project will improve our preparedness for the emergence of both known and novel pathogenic hantavirus species.