Related Experiment Video
Updated: Aug 22, 2026
An In vitro Model to Study Immune Responses of Human Peripheral Blood Mononuclear Cells to Human Respiratory Syncytial Virus Infection
Published on: December 10, 2013
Recombinant respiratory syncytial virus lacking secreted glycoprotein G is attenuated, non-pathogenic but induces
Caroline F Maher1, Tracy Hussell, Edward Blair
1Respiratory Medicine, Imperial College, St. Mary's Campus, Norfolk Place, London W2 1PG, UK.
Abstract:
Respiratory syncytial virus (RSV) causes intense pulmonary inflammatory responses in some infected infants. The surface attachment protein 'G' of RSV has membrane-bound and secreted forms and shows homology to the CX3C chemokine fractalkine. Using recombinant techniques, we generated replication-competent recombinant clonal RSV expressing normal G proteins ('rRSV') or only the membrane-bound form of G ('Gmem rRSV'). Both recombinants grew well in HEp-2 cells, but after primary intranasal infection in mice, pulmonary Gmem rRSV replication was reduced tenfold compared to parental or rRSV; moreover, CCL2 and CCL5 production was greatly reduced and no apparent disease or pulmonary cellular infiltration was observed. However, Gmem rRSV-infected mice developed good antibody responses and were fully protected against subsequent intranasal challenge with parental virus. Even in mice sensitized to G by cutaneous infection with recombinant vaccinia expressing G, intranasal challenge with Gmem rRSV caused insignificant disease. We conclude that secreted G is a key viral product assisting virus replication in vivo, enhancing CCL2 and CCL5 production and promoting illness. Engineered RSV mutants lacking the ability to secrete G are thus promising vaccine candidates.
Insights
Secreted G protein from respiratory syncytial virus (RSV) enhances viral replication and causes illness. RSV mutants lacking secreted G show reduced replication but still induce protective immunity, making them promising vaccine candidates.
Area of Science:
- Virology
- Immunology
- Molecular Biology
Background:
- Respiratory syncytial virus (RSV) infection in infants can lead to severe pulmonary inflammation.
- The RSV G protein, a surface attachment protein, exists in membrane-bound and secreted forms and shares similarities with the CX3C chemokine fractalkine.
- The role of the secreted form of the G protein in RSV pathogenesis and immune response is not fully understood.
Purpose of the Study:
- To investigate the role of the secreted G protein of RSV in viral replication, pathogenesis, and immune response in vivo.
- To evaluate the potential of engineered RSV mutants lacking secreted G as vaccine candidates.
Main Methods:
- Generation of replication-competent recombinant RSV expressing either normal G proteins (rRSV) or only the membrane-bound form of G (Gmem rRSV).
- Intranasal infection of mice with rRSV or Gmem rRSV to assess viral replication, cytokine production (CCL2, CCL5), and pulmonary cellular infiltration.
- Evaluation of antibody responses and protection against subsequent RSV challenge in Gmem rRSV-infected mice.
- Assessment of disease severity in mice sensitized to G protein and challenged with Gmem rRSV.
Main Results:
- Gmem rRSV showed significantly reduced pulmonary replication (tenfold decrease) compared to parental or rRSV in mice.
- CCL2 and CCL5 production was markedly reduced in mice infected with Gmem rRSV, with no apparent disease or pulmonary inflammation observed.
- Mice infected with Gmem rRSV developed robust antibody responses and were fully protected against subsequent challenge with wild-type RSV.
- Even in G-sensitized mice, intranasal challenge with Gmem rRSV resulted in insignificant disease.
Conclusions:
- The secreted form of the RSV G protein is crucial for efficient viral replication in vivo.
- Secreted G enhances the production of inflammatory chemokines (CCL2, CCL5), contributing to RSV-induced illness.
- RSV mutants engineered to lack secreted G are attenuated in replication and pathogenesis but retain immunogenicity, representing promising vaccine candidates.
