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Evaluation of orally administered valacyclovir in experimentally EHV1-infected ponies.
Abstract: The purpose of the current study was to investigate the therapeutic efficacy of valacyclovir against EHV1 in a controlled study. Eight naïve Shetland ponies were inoculated with 10(6.5) TCID(50) of the neuropathogenic strain 03P37. Four ponies were treated with valacyclovir at a dosage of 40mg/kg bodyweight, 3 times daily, for 5 (n=2) or 7 (n=2) consecutive days, while the other four ponies served as untreated controls. The treatment regimen started 1h before inoculation. Ponies were monitored daily for clinical signs. At 0, 1, 2, 3, 4, 5, 7, 9, 11, 14, 17 and 21 days post inoculation (d pi), a nasopharyngeal mucus sample was taken to determine viral shedding. At the same time points, blood was collected and peripheral blood mononuclear cells (PBMC) were isolated to determine viremia. During the treatment, blood samples were collected 6 times daily, i.e. just before valacyclovir administration and 1h later, to determine the concentration of acyclovir in plasma. Also a nasopharyngeal swab was taken to measure the acyclovir concentration in nasal secretion. No differences could be noticed between valacyclovir-treated and untreated ponies. The clinical signs, the viral shedding and the viremia were similar in both the groups. Plasma acyclovir concentration could be maintained above the EC(50)-value of EHV1 during 50% of the entire treatment period in valacyclovir-treated ponies. Acyclovir could be detected in nasal swabs at concentrations varying from 50% to 100% of the corresponding plasma concentration. Although sufficiently high acyclovir levels could be reached in plasma and nasal mucus, no effect was seen of the treatment with valacyclovir on clinical signs, viral shedding and viremia of EHV1-infected ponies.
Publication Date: 2008-09-21 PubMed ID: 18986780DOI: 10.1016/j.vetmic.2008.09.062Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
Summary
This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.
This research primarily focuses on the effectiveness of valacyclovir, an antiviral medication, in treating Equine Herpes Virus-1 (EHV1) in ponies. Despite administering the expected therapeutic level of the medication to experimentally infected ponies, the study found no noticeable differences in infection symptoms, virus shedding, or bloodstream virus presence between treated and untreated animals.
Research Design and Methodology
- The research used eight Shetland ponies that had never been exposed to EHV1. These ponies were experimentally infected with a neuropathogenic strain of EHV1.
- A dosage of 40mg/kg of valacyclovir was administered three times daily to half of the ponies (four out of eight) for either 5 or 7 consecutive days. The treatment began 1 hour prior to infecting the ponies with EHV1. The remaining four ponies were utilized as controls and did not receive any treatment.
- All the ponies were observed daily for clinical signs of illness. They were also tested regularly post-infection to monitor viral shedding (the process through which a virus is expelled and can infect new hosts) through nasopharyngeal mucus samples and to detect the presence of the virus in their blood.
Key Findings
- The study revealed that there were no differences in clinical symptoms, virus shedding, and the presence of the virus in the bloodstream (viremia) between the valacyclovir-treated ponies and the untreated ones.
- In the treated ponies, the researchers marked that the plasma concentration of acyclovir, the active form of valacyclovir, remained above the suggested effective concentration against EHV1 for 50% of the treatment period.
- They also noticed the presence of acyclovir in the nasal secretions of the treated ponies, with concentrations ranging from 50% to 100% of the corresponding plasma concentration.
Conclusion
- The study concluded that despite the placebo-controlled design and the achievement of therapeutically relevant concentrations of acyclovir in plasma and nasal secretions, no effect was observed on the progression or control of EHV1 infection in the treated ponies.
- This implies that while valacyclovir can achieve expected therapeutic concentrations in plasma and nasal secretions, it might not be effective in reducing symptoms, controlling viral shedding, or lowering viremia in ponies affected by EHV1.
Cite This Article
APA
Garré B, Gryspeerdt A, Croubels S, De Backer P, Nauwynck H.
(2008).
Evaluation of orally administered valacyclovir in experimentally EHV1-infected ponies.
Vet Microbiol, 135(3-4), 214-221.
https://doi.org/10.1016/j.vetmic.2008.09.062 Publication
Researcher Affiliations
- Department of Pharmacology, Toxicology and Biochemistry, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium. barbara.garre@ugent.be
MeSH Terms
- Acyclovir / analogs & derivatives
- Acyclovir / blood
- Acyclovir / therapeutic use
- Animals
- Antiviral Agents / blood
- Antiviral Agents / therapeutic use
- Body Temperature / drug effects
- Dose-Response Relationship, Drug
- Fever / drug therapy
- Fever / veterinary
- Herpesviridae Infections / drug therapy
- Herpesviridae Infections / veterinary
- Herpesvirus 1, Equid / drug effects
- Herpesvirus 1, Equid / isolation & purification
- Horse Diseases / drug therapy
- Horse Diseases / virology
- Horses
- Valacyclovir
- Valine / analogs & derivatives
- Valine / blood
- Valine / therapeutic use
- Virus Shedding / drug effects
Citations
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