A single-dose ChAdOx1-vectored vaccine provides complete protection against Nipah Bangladesh and Malaysia in Syrian golden hamsters

Abstract

Nipah virus (NiV) is a highly pathogenic re-emerging virus that causes outbreaks in South East Asia. Currently, no approved and licensed vaccine or antivirals exist. Here, we investigated the efficacy of ChAdOx1 NiVB, a simian adenovirus-based vaccine encoding NiV glycoprotein (G) Bangladesh, in Syrian hamsters. Prime-only as well as prime-boost vaccination resulted in uniform protection against a lethal challenge with NiV Bangladesh: all animals survived challenge and we were unable to find infectious virus either in oral swabs, lung or brain tissue. Furthermore, no pathological lung damage was observed. A single-dose of ChAdOx1 NiVB also prevented disease and lethality from heterologous challenge with NiV Malaysia. While we were unable to detect infectious virus in swabs or tissue of animals challenged with the heterologous strain, a very limited amount of viral RNA could be found in lung tissue by in situ hybridization. A single dose of ChAdOx1 NiVB also provided partial protection against Hendra virus and passive transfer of antibodies elicited by ChAdOx1 NiVB vaccination partially protected Syrian hamsters against NiV Bangladesh. From these data, we conclude that ChAdOx1 NiVB is a suitable candidate for further NiV vaccine pre-clinical development.

Fig 1. Single-dose vaccination with ChAdOx1 NiV_B protects Syrian hamsters against a lethal challenge with NiV Bangladesh.

(a) Experimental layout. P/B = prime-boost; B = bleed; V-N = ChAdOx1 NiV_B vaccination; V-G = ChAdOx1 GFP injection; S = saline injection; C = challenge; N = necropsy; T = Termination experiment. (b) Neutralizing antibodies in serum were determined via virus neutralization assay on VeroE6 cells at D-73, D-45 and D-3. (c) Survival of Syrian hamsters challenged with NiV Bangladesh. Survival of vaccinated animals was significant compared to control animals (P = <0.0001). (d) Weight loss of challenged animals. (e) Shedding of infectious virus in oropharyngeal swabs collected daily from challenged animals. NiV titers were determined via endpoint titration on VeroE6 cells. (f) Infectious virus titers in lung and brain tissue collected from challenged animals at D5. NiV titers were determined via endpoint titration on VeroE6 cells.

Fig 2. Single-dose vaccination with ChAdOx1 NiV_B protects Syrian hamsters against bronchointerstitial pneumonia caused by NiV Bangladesh challenge.

Hamsters were vaccinated with ChAdOx1 NiV_B or injected with ChAdOx1 FGP or saline and challenged with NiV Bangladesh. Lung tissue was collected at D5. Tissue sections were stained with hematoxylin-eosin (left panels) or with target-specific probes for NiV RNA, which is visible as a red-brown staining (right panels). (a-b) Lung tissue obtained at D5 of animals vaccinated with a single-dose of ChAdOx1 NiV_B. (c-d) Lung tissue obtained at D5 of animals vaccinated with a prime-boost regime of ChAdOx1 NiV_B. (e-f) Lung tissue obtained at D5 of animals injected with a prime-boost regime of ChAdOx1 FGP. (g-h) Lung tissue obtained at D5 of animals injected with saline. Arrow = Inflammatory cells, fibrin, edema and hemorrhage centered on terminal bronchioles. 200x magnification. H&E and ISH slides were from sequential sections.

Fig 3. Single-dose vaccination with ChAdOx1 NiV_B protects Syrian hamsters against a lethal challenge with NiV Malaysia, but not HeV.

(a) Experimental layout. B = bleed; V-N = ChAdOx1 NiV_B vaccination; V-G = ChAdOx1 FGP injection; C = challenge; N = necropsy; T = Termination experiment. (b) Neutralizing antibodies in serum were determined via virus neutralization assay on VeroE6 cells at D-31 and D-3. (c) Survival of Syrian hamsters challenged with NiV Malaysia or HeV. (d) Weight loss of challenged animals. (e) Shedding of infectious virus in oropharyngeal swabs collected daily from challenged animals. Virus titers were determined via endpoint titration on VeroE6 cells. (f) Infectious virus titers in lung and brain tissue collected from challenged animals at D4 (HeV) or D5 (NiV). Virus titers were determined via endpoint titration on VeroE6 cells.

Fig 4. Single-dose vaccination with ChAdOx1 NiV_B protects Syrian hamsters against severe bronchointerstitial pneumonia caused by NiV Malaysia challenge, but not by HeV challenge.

Hamsters were vaccinated with ChAdOx1 NiV_B or injected with ChAdOx1 FGP and challenged with NiV Malaysia or HeV. Lung tissue was collected at D4 (HeV) or D5 (NiV). Tissue sections were stained with hematoxylin-eosin (left panels) or with target-specific probes for viral RNA, which is visible as a red-brown staining (right panels). (a-b) Lung tissue obtained at D5 of animals vaccinated with a single-dose of ChAdOx1 NiV_B and challenged with NiV Malaysia. (c-d) Lung tissue obtained at D5 of animals injected with a single-dose of ChAdOx1 FGP and challenged with NiV Malaysia. (e-f) Lung tissue obtained at D5 of animals vaccinated with a single-dose of ChAdOx1 NiV_B and challenged with HeV. (g-h) Lung tissue obtained at D5 of animals injected with a single-dose of ChAdOx1 FGP and challenged with HeV. Arrow in H&E = Inflammatory cells, fibrin, edema and hemorrhage centered on terminal bronchioles. Arrow in ISH = Positive endothelial cells lining an artery. 200x magnification. H&E and ISH slides were from sequential sections.

Fig 5. Treatment with ChAdOx1 NiV_B elicited antibodies provides partial protection against a lethal NiV Bangladesh challenge in Syrian hamsters.

(a) Experimental layout. B = bleed; P = passive transfer; C = challenge; N = necropsy; T = Termination experiment. (b) Reciprocal titer of NiV Bangladesh G protein-specific antibodies in serum as determined via ELISA at pre-treatment and post-treatment. As a control, serum obtained from animals vaccinated via prime only (Fig 1) were taken along. (c) Survival of animals challenged with NiV Bangladesh treated with NiV or GFP antibodies. (d) Weight loss of challenged animals. (e) Shedding of infectious virus in oropharyngeal swabs collected daily from challenged animals. (f) Infectious virus titers in lung and brain tissue collected from challenged animals at D5. Virus titers were determined via endpoint titration on VeroE6 cells.

Fig 6. Treatment with IgG antibodies elicited by ChAdOx1 NiV_B vaccination reduced pathology and viral RNA abundance in Syrian hamsters challenged with NiV Bangladesh.

Hamsters were treated with NiV or GFP antibodies and challenged with NiV Bangladesh. Lung tissue was collected at D5. Tissue sections were stained with hematoxylin-eosin (left panels) or with target-specific probes for viral RNA, which is visible as a brown staining (right panels). (a-b) Lung tissue obtained at D5 of animals treated with NiV antibodies. (c-d) Lung tissue obtained at D5 of animals treated with GFP antibodies. Arrow in H&E = Inflammatory cells, fibrin, edema and hemorrhage centered on terminal bronchioles. 200x magnification. H&E and ISH slides were from sequential sections.