TABLE 3.
Summary of main findings from studies evaluating abortion following EHV‐1 exposure.
| Study identifier | Study design | Virus | Dose (route) | Outcome incidence | Main findings: viremia |
|---|---|---|---|---|---|
| Burki (1990) | NRES | Piber 178/83 | 107 TCID50 (IN) | Fever ≥ 38.6°C: 7/10, abortion: 5/10 | Viremia (horse kidney cells): 5/5 (PF that aborted); 4/5 (PF that delivered foals). SN titers (Δ 14 dpi − pre): PF that aborted: 268 ± 152; PF that delivered foals: 368 ± 140 (P = .36; post hoc analysis) |
| Gardiner (2012) | NRES | OHO3 | 5 × 107 PFU (IN) | Fever ≥ 1°C rise above baseline: 7/7, abortion: 1/7 | Viremia (qpcr): 7/7. Viremic between 5 and 8 dpi, with a duration of 1‐4 d. Mare #d that aborted was viremic for the longest duration of 4 d. Mare that aborted: Peak viremia (5 dpi): 103.0 EHV‐1 gB copies/106 beta Actin copies. Peak viremia in mares that did not abort at 5‐7 dpi: 102.9‐103.6 EHV‐1 gB copies/106 beta Actin copies. Aborted fetuses had lesions in the liver, adrenal glands, and spleen. |
| Ab4 | Fever ≥ 1°C rise above baseline: 7/7, abortion: 5/7 | Viremia (qpcr): 7/7. Viremic between 5 and 8 dpi with a duration of 1‐3 d. The two mares that delivered healthy foals showed the shortest duration of viremia. Mares that aborted: Peak viremia (5‐9 dpi): 102.3‐103.2. Peak viremia in mares that did not abort at 5‐7 dpi: 102.1‐102.3 EHV‐1 gB copies/106 beta Actin copies. Aborted fetuses had lesions in the liver, adrenal glands, and spleen. | |||
| Gleeson and Coggins (1980) | NRES | Army 183 | 5 × 107.5 TCID50 (nasal nebulized) | Fever: 11/11, abortion: 1/11. Nasal shedding 8/8. | Viremia (horse kidney cells): 10/11. Aborted foal was negative for virus. Mean duration of viremia 4.2 ± 2.4 d. |
| KyB | 5 × 106.5 TCID50 (IN) | Fever: 5/10, abortion: 1/10. Nasal shedding 5/10. | Viremia (horse kidney cells): 8/10, mean duration of viremia 3.5 ± 2.9 d. Aborted foal was positive for virus. | ||
| Heldens (2001) | NRES |
Ab4 (Controls) |
2 × 106.0 TCID50 | Fever (>38.8°C): 4/5; abortion: controls 5/5. | Viremia (horse kidney cells): 5/5. Viral titers (PBMC) not provided. Mean duration of viraemia: 4.3 d. |
|
Ab4 (Vaccinated) |
Fever (>38.8°C): 2/4, abortion: 1/5. | Viremia (horse kidney cells): 5/5. Viral titers (PBMC) not provided. Mean duration of viremia: 4.0 d. | |||
| Kydd (2003) | NRES |
Ab4/8 (Controls) |
1 × 105.0 TCID50 (IN) | Fever: 9/9; nasal shedding: 3.6 ± 1.1, abortion: 9/9 | Viremia: controls 9/9; duration of viremia: 4.3 ± 1.9 d. Viral titers (PBMC) not provided. |
|
Ab4/8 (Vaccinated) |
Fever: 5/5, nasal shedding: 2.2 ± 1.1 d, abortion: 1/5. | Viremia: 5/5, duration of viremia: 4.0 ± 1.2 d. Viral titers (PBMC) not provided. | |||
| Mumford (1991) | NRES |
AB4 Controls |
107 TCID50 (IN) | Fever: 9/9, abortion 8/9 | Viremia (rabbit kidney cells): 9/9. Viral titers (PBMC) not provided. |
|
AB4 Vaccinated |
Fever 10/10, abortion: 9/10 | Viremia (rabbit kidney cells): 10/10. Viral titers (PBMC) not provided. | |||
| Mumford (1994) | NRES | V592 | 30 or 50 × 107.5 TCID50 (IN aerosol) | Fever 8/10, abortion 1/10 | Viremia (rabbit kidney cells): 10/10. Viral titers (PBMC) not provided. |
| Ab4 | 20 × 106.7 TCID50 (IN aerosol) | Fever 8/8, abortion 4/8 | Viremia (rabbit kidney cells): 8/18, mean duration of viremia: 3.1 d. Viral titers (PBMC) not provided. | ||
| 30 × 107.5 TCID50 (IN aerosol) | Fever 7/7, abortion 3/5 | Viremia (rabbit kidney cells): 7/7, mean duration of viremia: 8.2 d. Viral titers (PBMC) not provided. | |||
| 103 to 107 TCID50 (IN) | Fever 35/41, abortion 27/35 | Viremia (rabbit kidney cells): 15/15. Viral titers (PBMC) not provided. | |||
| Patel (2003) | NRES |
Ab4 Control |
2 × 105.7 TCID50 (IN) | Fever: 6/6, nasal shedding 6/6, duration nasal shedding 6.5 ± 0.8 d, abortion 6/6 | Viremia: 6/6, duration 2.3 ± 0.5 d. Viral titers (PBMC) not provided. |
|
Ab4 Vaccinated 4 mo |
Fever: 3/5, nasal shedding 5/6, duration nasal shedding 2.2 ± 1.1 d, abortion 1/5 | Viremia: 2/5, duration 2.0 ± 1.4 d. Viral titers (PBMC) not provided. | |||
|
Ab4 Vaccinated 5 mo |
Fever: 2/6, nasal shedding 4/6, duration nasal shedding 2.5 ± 1.3 d, still birth 1/6 | Viremia: 3/6, duration 1.0 ± 0 d. Viral titers (PBMC) not provided. |
Abbreviations: Ct, cycle threshold; IN, intranasal; NRES, non‐randomized experimental study; PBMC, peripheral blood mononuclear cell; pcr, polymerase chain reaction; qpcr, quantitative real time PCR; RCT, randomized controlled trial; RK, rabbit kidney.