Viral Immunology

Our laboratory is situated in the Henry Wellcome Building at the MRC-University of Glasgow Centre for Virus Research (CVR). Our main interests are the ways in which viruses cause disease; the immune response to infection; and the development of viral vaccines.

Our work focuses on viruses of importance to human and veterinary medicine, including coronaviruses, morbilliviruses, caliciviruses, bunyaviruses, lentiviruses, rhabdoviruses and parvoviruses. Active research projects are investigating:

  • cross-neutralisation of SARS-CoV-2 variants
  • determinants of SARS-CoV-2 virulence, evasion of immunity and vaccine effectiveness
  • correlates of immunity to circulating measles virus genotypes
  • cross-species transmission and antibody-mediated neutralisation of morbilliviruses
  • SARS-CoV-2 spread in the UK domestic cat population
  • Drivers of bunyavirus emergence in pastoral and agropastoral communities in Africa

Immunity to SARS-CoV-2

Seroprevalence of SARS-CoV-2 in NHS GGC

In early 2020, we initiated a program of research aimed at investigating the antibody response to infection with SARS-CoV-2, with a view to tracking the spread of the virus throughout the community and assessing the level of immunity elicited by infection. By combining in-house ELISA assays with pseudotype-based neutralisation assays, we were able to track the spread of SARS-CoV-2 across NHS Greater Glasgow and Clyde, the largest health board in Scotland (Hughes et al. 2021). We showed that males, 45-64-years olds, and patients in secondary care were most likely to be seropositive. Further, we established that approximately half of seropositive individuals (assessed by ELISA) developed neutralising antibodies (Hughes et al. 2021).

 

Lineage-specific neutralisation of SARS-CoV-2 by vaccine seraBuilding on these studies, we examined evasion of the neutralising response by the Beta and Delta variants of SARS-CoV-2 (Davies et al. 2021), and the effect of antigenic variation on evasion of the immune response elicited by vaccination with either ChAdOx1 (AstraZeneca) or BNT162b2 (Pfizer) vaccines. The emergence of the Omicron lineage of viruses at the end of 2021 signalled a new phase in the evolution of SARS-CoV-2.

 

Working closely with colleagues across the University of Glasgow and the wider UK academic and healthcare communities, we established that the Omicron variant had a phenotype that had changed fundamentally compared with all prior variants (Research briefing). The Omicron variants displayed reduced neutralisation by antibodies elicited by vaccination, while T cell responses were relatively preserved (Willett et al. 2022). Further, real-world vaccine effectiveness was partially restored by booster vaccination. Our study revealed that Omicron displayed distinct entry and fusion properties to preceding variants, entering cells via a TMPRSS2-independent, endosomal entry pathway (Willett et al. 2022). This fundamental change in the viral entry mechanism was not predicted by sequencing data; rather it was revealed by observations in cell culture experiments from several laboratories, including those at the CVR. This project was supported in part by HDR-UK, further details are available here.

One of our primary SARS-CoV-2 research objectives is to elucidate the nature of the virus-host interaction;  investigating the strength, specificity and duration of humoral immunity. Working closely with colleagues at the University of Birmingham, we are currently investigating vaccine effectiveness in at-risk populations; including children (Dowell et al, 2022a & Dowell et al., 2022b), the elderly and patients with chronic lymphocytic leukemia (Parry et al, 2022a & Parry et al, 2022b). These studies will inform future vaccine strategies for preventing SARS-CoV-2 infection and the development of COVID-19.

Emerging morbilliviruses of wildlife and humans

The rapid global spread of peste des petits ruminants virus (PPRV), from 1942 to the present day. Once restricted to West Africa, the virus now infects animals across Africa and the Middles East, Turkey, India and China. 

The global spread of peste des petits ruminants virus (PPRV)

In May 2011, the General Session of the Office International des Epizooties declared the world to be free from rinderpest virus, the causative agent of “cattle plague”. Rinderpest virus (RPV) is a morbillivirus, a close relative of measles virus (MeV). Like rinderpest virus, measles virus is now being considered for global eradication by vaccination. However, there is increasing concern that if such a vaccination programme was to be successful, the requirement for vaccination would cease. As a result, humans would no longer have cross-protection against zoonotic infections with closely-related animal morbilliviruses. Significant concerns have now been raised about the threat from the carnivore morbillivirus, canine distemper virus (CDV), a virus capable of infecting diverse species including dogs, ferrets, martens, lions, hyenas and seals. This ability to cross species renders CDV a significant threat to many endangered species of wildlife. Moreover, pathogenic CDV infections have been described in primates, raising the possibility of zoonotic transmissions to humans. There is now intense interest in the viral reservoirs of CDV and the degree of cross-protection conferred by MV vaccination as a means of guarding against cross-species transmission.

Neutralisation of morbilliviruses by antibodies is currently measured using a restricted subset of live viruses that grow readily in culture. Thus it is not possible to compare antibody responses to vaccine viruses with those against primary field strains of virus, making predictions of vaccine efficacy and likelihood of zoonotic transmission challenging. We have developed novel viral pseudotype-based assay systems with which serological responses to diverse animal morbilliviruses can be measured rapidly, with high sensitivity and specificity (see Logan et al. 2016a & Logan et al., 2016b). Using this simple methodology, we are measuring neutralizing antibody responses against primary field strains of virus, novel emerging morbilliviruses, and unique biotypes and serotypes of virus for which assays are currently unavailable. We have developed parallel systems for diverse morbilliviruses; viral pseudotypes based on peste des petits ruminants (PPRV), CDV, RPV, MeV and phocine distemper virus (PDV), and target cell lines expressing the cognate receptors for each virus.

This project brings a comprehensive understanding of the spread of morbilliviruses in livestock (Herzog et al., 20192020a & 2020b) and wildlife species (Gilbert et al., 2020). It addresses whether morbilliviruses are being maintained in atypical host species and whether these species are a source of infection for susceptible hosts. It provides epidemiological and biological data to inform future strategies for virus eradication by vaccination, illuminating the extent of virus spread and the likely species that will require to be vaccinated. The high-throughput assay techniques we employ build capacity in the UK for "rapid response" to emerging viral diseases.

Listen to Prof. Willett discussing morbillivirus research at the CVR here: CVR Podcast

Research highlights: viral receptors

The primary receptor for FIV

viral receptors

The initial event in the process of viral infection involves the binding of the virus to a molecule on the cell surface. Therefore, the expression pattern of this molecule within the host determines which cell types the virus will target. The receptor for human immunodeficiency virus (HIV) is CD4, a molecule that is expressed primarily on a specialised subset of cells within the immune system known as helper T cells (Th cells). Th cells play a pivotal role in the development of specific immune responses to pathogens and by targeting and destroying these cells selectively, HIV impairs the ability of the immune system to respond to infection. Consequently, HIV-infected individuals develop opportunistic infections and ultimately AIDS (acquired immune deficiency syndrome).

Although FIV targets Th cells, it has been known for several years that the virus does not use CD4 as a primary receptor. In a recent study, published in the journal Science, researchers from the Retrovirus Research Laboratory joined with colleagues in London and Japan to show that the primary receptor for FIV was a molecule known as CD134 (OX40).

What is CD134?

CD134

CD134 belongs to a large group of related molecules known as the nerve growth factor (NGF)/tumour necrosis factor (TNF) receptor superfamily. The molecule was first identified as "OX40", an antigen expressed on the surface of rat Th cells. It was subsequently found to be identical to an activation antigen found on human T cells known as "BerACT35".

The molecule functions in the development of antigen-specific T cell responses where it supports T cell expansion and survival by interacting with its ligand, CD134L (OX40L) on antigen presenting cells. Expression of feline CD134 expression on non-susceptible cells (eg human cells) renders the cells permissive for infection with FIV. Infection requires co-expression of a second molecule, CXCR4, a molecule we identified previously as the major co-receptor for FIV (see Nature 1997 J. Virology 1997).

Group members

 

Viral immunology group members in 2022 

Diagnostic tools

Monoclonal antibodies

Many of the antibodies generated in our laboratory can be purchased from Bio-Rad. The current list of reagents available is as follows:

Feline leucocyte differentiation antigens

Specificity  

Designation  

Catalogue number

Applications 

CD134 7D6 MCA2568 FC,WB
CD134-FITC 7D6 MCA2568F FC
CD134-A488 7D6 MCA2568A488 FC
CD134-A647 7D6 MCA2568A647 FC

CD4

vpg34

MCA1346 

FC, IP

CD4-FITC* 

vpg34

MCA1346F

FC

CD4 

vpg38

MCA1350

FC, IP

CD4

vpg39

MCA1349

FC, IP

CD8-RPE*

vpg9

MCA1347PE

FC

CD9

vpg15

MCA1345

FC, IP

MHC class II

vpg3

MCA1348

FC, IP

*CD4-FITC and CD8-RPE may be used for dual colour analysis of feline T cell subsets in a single tube format. The histograms below represent an analysis of T cell subsets in an FIV-infected cat using vpg34-FITC and vpg9-PE. Note the appearance of the "CD8low" sub-population (Immunology (1993), 78:1-6), a sub-population of CD8+ T cells thought to be CD8a  + b low (J Gen Virol. (1998), 79:91-94). This population is often observed in FIV infected cats.

Feline Immunodeficiency Virus

Specificity

Designation Catalogue number Applications
gp120 vpg68 MCA1351 IFA, FC, IP
p24 gag vpg50 MCA1353 IFA, IP, WB

Glutathione-S-Transferase

Specificity Designation

Catalogue number

Applications
GST vpg66 MCA1352 WB, IP
GST-biotinylated vpg66 MCA1352B WB, IP

vpg66 will recognise fusion proteins generated using the pGEX-2T vector and is ideal for both immunoprecipitation and western blot analyses. The use of vpg66 to detect fusion proteins between the HIV-1 Nef protein and GST is detailed in Harris, M. and Coates, K.C. (1993). J. Gen. Virol. 74, 1581-1589 and Harris, M.P.G. and Neil, J.C. (1994). J. Mol. Biol. 241, 136-142.

Additional antibodies against feline leukaemia virus, distinct epitopes on feline CD4, FIV p24 or FIV gp120 are available. Further information can be obtained from either our laboratory or Bio-Rad.