Effects of Different Adjuvants on the Protective Efficacy of a Subcellular Vaccine Against <i>Chlamydia abortus</i> Infection in Sheep
Background/Objective: Recently, we published three studies describing the development and optimization of a new, safe, and efficacious vaccine to protect sheep from ovine enzootic abortion, which is caused by the zoonotic pathogen <i>Chlamydia abortus</i>. The vaccine, which can be deliv...
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MDPI AG
2025-06-01
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| Series: | Vaccines |
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| Online Access: | https://www.mdpi.com/2076-393X/13/6/609 |
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| author | Morag Livingstone Kevin Aitchison Javier Palarea-Albaladejo Sergio Gastón Caspe Clare Underwood Holly Hill Cameron Cunnea Kelly Stronach Francesca Chianini Gary Entrican Sean Ranjan Wattegedera David Longbottom |
| author_facet | Morag Livingstone Kevin Aitchison Javier Palarea-Albaladejo Sergio Gastón Caspe Clare Underwood Holly Hill Cameron Cunnea Kelly Stronach Francesca Chianini Gary Entrican Sean Ranjan Wattegedera David Longbottom |
| author_sort | Morag Livingstone |
| collection | DOAJ |
| description | Background/Objective: Recently, we published three studies describing the development and optimization of a new, safe, and efficacious vaccine to protect sheep from ovine enzootic abortion, which is caused by the zoonotic pathogen <i>Chlamydia abortus</i>. The vaccine, which can be delivered through a single inoculation, is based on a detergent-extracted outer membrane protein (chlamydial outer membrane complex or COMC) preparation of the pathogen. This study aimed to optimize the vaccine further by comparing the effects of different adjuvants on protective efficacy. Methods: We evaluated the effectiveness of three different vaccines (2.5 µg COMC) formulated with one of three adjuvants (Montanide ISA 70VG, Montanide ISA 61VG, and QuilA) to reduce the rate of abortion, placental load and pathology, and post-partum vaginal shedding of organisms in comparison to our benchmark 20 µg COMC/Montanide ISA 70 VG vaccine and a challenge control group of animals. The humoral and cellular immunological responses to vaccination and to challenge were also assessed. Results: The two low-dose Montanide formulated vaccines resulted in low abortion rates of 3.2 and 8.1% for ISA 70 VG and ISA 61 VG, respectively, which were comparable to the benchmark vaccine group (2.7%) and considerably lower than the QuilA (23.7%) and challenge control (36.8%) groups. Similarly, the Montanide-adjuvanted groups had much lower bacterial loads (range: 136–431 genome copies) on vaginal swabs post-parturition than the QuilA (8.9 × 10<sup>4</sup> copies) and challenge control (2.4 × 10<sup>5</sup> copies) groups. Conclusions: The results showed that both Montanide adjuvants are more effective for maximizing COMC vaccine efficacy than the QuilA adjuvant and result in much lower bacterial shedding of the pathogen post-parturition, which is important for minimizing potential transmission to naïve animals. |
| format | Article |
| id | doaj-art-a06e4fdf44d24ba7903a9a69e320c177 |
| institution | Kabale University |
| issn | 2076-393X |
| language | English |
| publishDate | 2025-06-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Vaccines |
| spelling | doaj-art-a06e4fdf44d24ba7903a9a69e320c1772025-08-20T03:32:28ZengMDPI AGVaccines2076-393X2025-06-0113660910.3390/vaccines13060609Effects of Different Adjuvants on the Protective Efficacy of a Subcellular Vaccine Against <i>Chlamydia abortus</i> Infection in SheepMorag Livingstone0Kevin Aitchison1Javier Palarea-Albaladejo2Sergio Gastón Caspe3Clare Underwood4Holly Hill5Cameron Cunnea6Kelly Stronach7Francesca Chianini8Gary Entrican9Sean Ranjan Wattegedera10David Longbottom11Moredun Research Institute, Pentlands Science Park, Penicuik, Midlothian EH26 0PZ, UKMoredun Research Institute, Pentlands Science Park, Penicuik, Midlothian EH26 0PZ, UKBiomathematics and Statistics Scotland, Edinburgh EH9 3FD, UKMoredun Research Institute, Pentlands Science Park, Penicuik, Midlothian EH26 0PZ, UKMoredun Research Institute, Pentlands Science Park, Penicuik, Midlothian EH26 0PZ, UKMoredun Research Institute, Pentlands Science Park, Penicuik, Midlothian EH26 0PZ, UKMoredun Research Institute, Pentlands Science Park, Penicuik, Midlothian EH26 0PZ, UKMoredun Research Institute, Pentlands Science Park, Penicuik, Midlothian EH26 0PZ, UKMoredun Research Institute, Pentlands Science Park, Penicuik, Midlothian EH26 0PZ, UKMoredun Research Institute, Pentlands Science Park, Penicuik, Midlothian EH26 0PZ, UKMoredun Research Institute, Pentlands Science Park, Penicuik, Midlothian EH26 0PZ, UKMoredun Research Institute, Pentlands Science Park, Penicuik, Midlothian EH26 0PZ, UKBackground/Objective: Recently, we published three studies describing the development and optimization of a new, safe, and efficacious vaccine to protect sheep from ovine enzootic abortion, which is caused by the zoonotic pathogen <i>Chlamydia abortus</i>. The vaccine, which can be delivered through a single inoculation, is based on a detergent-extracted outer membrane protein (chlamydial outer membrane complex or COMC) preparation of the pathogen. This study aimed to optimize the vaccine further by comparing the effects of different adjuvants on protective efficacy. Methods: We evaluated the effectiveness of three different vaccines (2.5 µg COMC) formulated with one of three adjuvants (Montanide ISA 70VG, Montanide ISA 61VG, and QuilA) to reduce the rate of abortion, placental load and pathology, and post-partum vaginal shedding of organisms in comparison to our benchmark 20 µg COMC/Montanide ISA 70 VG vaccine and a challenge control group of animals. The humoral and cellular immunological responses to vaccination and to challenge were also assessed. Results: The two low-dose Montanide formulated vaccines resulted in low abortion rates of 3.2 and 8.1% for ISA 70 VG and ISA 61 VG, respectively, which were comparable to the benchmark vaccine group (2.7%) and considerably lower than the QuilA (23.7%) and challenge control (36.8%) groups. Similarly, the Montanide-adjuvanted groups had much lower bacterial loads (range: 136–431 genome copies) on vaginal swabs post-parturition than the QuilA (8.9 × 10<sup>4</sup> copies) and challenge control (2.4 × 10<sup>5</sup> copies) groups. Conclusions: The results showed that both Montanide adjuvants are more effective for maximizing COMC vaccine efficacy than the QuilA adjuvant and result in much lower bacterial shedding of the pathogen post-parturition, which is important for minimizing potential transmission to naïve animals.https://www.mdpi.com/2076-393X/13/6/609<i>Chlamydia abortus</i>ovine enzootic abortionvaccine developmentvaccine efficacygross placental pathologyquantitative real-time PCR |
| spellingShingle | Morag Livingstone Kevin Aitchison Javier Palarea-Albaladejo Sergio Gastón Caspe Clare Underwood Holly Hill Cameron Cunnea Kelly Stronach Francesca Chianini Gary Entrican Sean Ranjan Wattegedera David Longbottom Effects of Different Adjuvants on the Protective Efficacy of a Subcellular Vaccine Against <i>Chlamydia abortus</i> Infection in Sheep Vaccines <i>Chlamydia abortus</i> ovine enzootic abortion vaccine development vaccine efficacy gross placental pathology quantitative real-time PCR |
| title | Effects of Different Adjuvants on the Protective Efficacy of a Subcellular Vaccine Against <i>Chlamydia abortus</i> Infection in Sheep |
| title_full | Effects of Different Adjuvants on the Protective Efficacy of a Subcellular Vaccine Against <i>Chlamydia abortus</i> Infection in Sheep |
| title_fullStr | Effects of Different Adjuvants on the Protective Efficacy of a Subcellular Vaccine Against <i>Chlamydia abortus</i> Infection in Sheep |
| title_full_unstemmed | Effects of Different Adjuvants on the Protective Efficacy of a Subcellular Vaccine Against <i>Chlamydia abortus</i> Infection in Sheep |
| title_short | Effects of Different Adjuvants on the Protective Efficacy of a Subcellular Vaccine Against <i>Chlamydia abortus</i> Infection in Sheep |
| title_sort | effects of different adjuvants on the protective efficacy of a subcellular vaccine against i chlamydia abortus i infection in sheep |
| topic | <i>Chlamydia abortus</i> ovine enzootic abortion vaccine development vaccine efficacy gross placental pathology quantitative real-time PCR |
| url | https://www.mdpi.com/2076-393X/13/6/609 |
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