Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2023 Nov 14;11(11):1716.
doi: 10.3390/vaccines11111716.

Efficacy of Fowlpox Virus Vector Vaccine Expressing VP2 and Chicken Interleukin-18 in the Protection against Infectious Bursal Disease Virus

Affiliations

Efficacy of Fowlpox Virus Vector Vaccine Expressing VP2 and Chicken Interleukin-18 in the Protection against Infectious Bursal Disease Virus

Ibrahim Eldaghayes et al. Vaccines (Basel). .

Abstract

In mammals, the role of interleukin-18 (IL-18) in the immune response is to drive inflammatory and, normally therefore, anti-viral responses. IL-18 also shows promise as a vaccine adjuvant in mammals. Chicken IL-18 (chIL-18) has been cloned. The aim of this study was to investigate the potential of chIL-18 to act as a vaccine adjuvant in the context of a live recombinant Fowlpox virus vaccine (fpIBD1) against Infectious bursal disease virus (IBDV). fpIBD1 protects against mortality, but not against damage to the bursa of Fabricius caused by IBDV infection. The Fowlpox virus genome itself contains several candidate immunomodulatory genes, including potential IL-18 binding proteins (IL-18bp). We knocked out (Δ) the potential IL-18bp genes in fpIBD1 and inserted (::) the cDNA encoding chIL-18 into fpIBD1 in the non-essential ORF030, generating five new viral constructs -fpIBD1::chIL-18, fpIBD1ΔORF073, fpIBD1ΔORF073::chIL-18, fpIBD1ΔORF214, and fpIBD1ΔORF214::chIL-18. The subsequent protection from challenge with virulent IBDV, as measured by viral load and bursal damage, given by these altered fpIBD1 strains, was compared to that given by the original fpIBD1. Complete protection was provided following challenge with IBDV in chicken groups vaccinated with either fpIBDIΔ073::IL-18 or fpIBD1Δ214::IL-18, as no bursal damage nor IBDV was detected in the bursae of the birds. The results show that chIL-18 can act as an effective vaccine adjuvant by improving the fpIBD1 vaccine and providing complete protection against IBDV challenge.

Keywords: chicken interleukin-18; fpIBD1; recombinant Fowlpox virus FP9; vaccine adjuvant.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
PCR products from fpIBD1 showing the VP2-specific band (~1.6 kb). Lanes (a) Primers VP2 F (+BamHI site) and VP2 R (+BamHI site). Lane (b) Primers VP2 F (+EcoRI site) and VP2 R (+NotI site). M—DNA marker.
Figure 2
Figure 2
Blue plaques of fpIBD1 on X-gal overlay Agar (two different dilutions).
Figure 3
Figure 3
Homologous recombination between flanking sequence of ORF073 encoded by the plasmid and those in fpIBD1. The resulting recombinant fpIBD1 (RfpIBD1) was selected as gpt+. The selection of gpt− virus may result in either wild-type fpIBD1(WT fpIBD1) or knockout 073 (fpIBD1Δ073). The same method was used to generate knockout ORF214.
Figure 4
Figure 4
Cloning strategy resulting in the target plasmid containing the S promoter, ChIL-18, and flanking sequences of the PC-1 gene.
Figure 5
Figure 5
Real-time quantitative PCR: (A) Standard curve for pCI-neo::VP2.
Figure 6
Figure 6
Sequencing of the insert. S promoter sequences are shown with a green background and ChIL-18 sequences with yellow. The ChIL-18 primers used in this study and their positions are shown. The sequence in black is the remaining sequence between the NotI site and the insert (ChIL-18) in the original vector pGEM-T Easy.
Figure 7
Figure 7
PCR products from DNA preps of fpIBD1 (1), fpIBD1Δ073 (2), fpIBD1Δ214 (3), fpIBD1::IL-18 (4), fpIBD1Δ073::IL-18 (5), and fpIBD1Δ214::IL-18 (6), using primers IL-18/1 F and IL-18/5 R. (+ve): pGEM-T Easy::IL-18. (C): negative control. (M): DNA marker. The band in lane 6 is less intense due to a lower DNA concentration being used as a template in the PCR.
Figure 8
Figure 8
PCR products from DNA preps of fpIBD1 (1), fpIBD1Δ073 (2), fpIBD1Δ214 (3), fpIBD1::IL-18 (4), fpIBD1Δ073::IL-18 (5), and fpIBD1Δ214::IL-18 (6), using (A) primers 73Flk F and 73Flk R, (B) primers 214Flk F and 214FlkR and (C) primers IL-18/1 F and IL-18/5 R. +ve—pGEM-T Easy::IL-18. C—negative control. M—DNA marker.
Figure 9
Figure 9
Sections of bursae stained with H&E from birds infected with vIBDV strain F52/70, showing different bursal damage scores as detailed in Table 3: (A) = bursal damage score of 0, (B) = bursal damage score of 1, (C) = bursal damage score of 2, (D) = bursal damage score of 3, (E) = bursal damage score of 4, (F) = bursal damage score of 5. Arrows indicate the cortex (1), medulla (2), and cortico-medullary junction (3) of a bursal follicle.
Figure 10
Figure 10
Bursal tissue sections from different groups taken at 5 dpi with the vIBDV strain F52/70: (AD): The sections were stained with the anti-B cell monoclonal antibody, AV20, and counterstained with hematoxylin. (A): unvaccinated and unchallenged (-ve control), (B): vaccinated with fpIBD1 and challenged, (C): vaccinated with fpIBD1Δ214::IL-18 and challenged, (D): unvaccinated and challenged (+ve control). (EH): Bursal tissue sections stained with the anti-IBDV monoclonal antibody, R63, and counterstained with hematoxylin at 5 dpi. (E): unvaccinated and unchallenged, (F): vaccinated with fpIBD1 and challenged, (G): vaccinated with fpIBD1Δ214::IL-18 and challenged, (H): unvaccinated and challenged. Challenge was with 102.3 EID50 vIBDV strain F52/70 (100× magnification).
Figure 11
Figure 11
IBDV mRNA levels in the blood of unvaccinated birds (-ve control) and birds challenged with IBDV 102.3 EID50 strain F52/70 were quantified by real-time quantitative RT-PCR. Birds nos. 4 and 6 survived until the end of the experiment, whereas the other birds reached the clinical end point by 3 dpi. Results are expressed as 40-Ct values.
Figure 12
Figure 12
Viral loads (vIBDV strain F52/70) in the bursa 5 dpi: (1): -ve control; (2): +ve control (vIBDV); (3): fpIBD1; (4): fpIBD1Δ073; (5): fpIBD1Δ214; (6); fpIBD1::IL18; (7): fpIBD1Δ073::IL18; (8): fpIBD1Δ214::IL18; (9): fpIBD1; (10): fpIBD1Δ073; (11): fpIBD1Δ214; (12): fpIBD1::IL18; (13): fpIBD1Δ073::IL18; (14): fpIBD1Δ214::IL18; (Groups 2–8): Challenged with vIBDV; (Groups 9–14 and group 1): No challenge.

Similar articles

Cited by

References

    1. Cosgrove A. An Apparently New Disease of Chickens: Avian Nephrosis. Avian Dis. 1962;6:385. doi: 10.2307/1587909. - DOI
    1. Eterradossi N., Saif Y.M. Infectious bursal disease. In: Swayne D.E., Boulianne M., Logue C.M., McDougald L.R., Nair V., Suarez D.L., de Wit S., Grimes T., Johnson D., Kromm M., et al., editors. Diseases of Poultry. 14th ed. John Wiley & Sons, Inc.; Hoboken, NJ, USA: 2020. pp. 257–283.
    1. Gao H., Wang Y., Gao L., Zheng S.J. Genetic Insight into the Interaction of IBDV with Host—A Clue to the Development of Novel IBDV Vaccines. Int. J. Mol. Sci. 2023;24:8255. doi: 10.3390/ijms24098255. - DOI - PMC - PubMed
    1. Van der Berg T.P., Gonze M., Meulemans G. Acute infectious bursal disease in poultry: Isolation and characterisation of a highly virulent strain. Avian Pathol. 1991;20:133–143. doi: 10.1080/03079459108418748. - DOI - PubMed
    1. Hein R., Koopman R., García M., Armour N., Dunn J.R., Barbosa T., Martinez A. Review of Poultry Recombinant Vector Vaccines. Avian Dis. 2021;65:438–452. doi: 10.1637/0005-2086-65.3.438. - DOI - PubMed

LinkOut - more resources