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. 2021 Jun 9:12:149-158.
doi: 10.2147/VMRR.S306355. eCollection 2021.

Effect of a Topical Formulation on Infective Viral Load in Lambs Naturally Infected with Orf Virus

Delia Lacasta  1 , Ramses Reina  2 , Marta Ruiz de Arcaute  1 , Luis Miguel Ferrer  1 , Alfredo Angel Benito  3 , Maria Teresa Tejedor  4 , Irache Echeverria  2 , Hector Ruiz  1 , Silvia Martinez Cardenas  1 , Peter Andrew Windsor  5
Affiliations

Effect of a Topical Formulation on Infective Viral Load in Lambs Naturally Infected with Orf Virus

Delia Lacasta et al. Vet Med (Auckl). .

Abstract

Introduction: Orf is a highly contagious eruptive viral disease of the skin and mucosa of sheep and goats. Although vaccination with live or attenuated orf virus is the preferred option for disease control, the vaccine is unavailable in many countries. Treatment of orf lesions involves standard hygiene and in numerous cases, management of presumptive secondary infections with antibiotics, increasing risks of antimicrobial resistance (AMR). The wound dressing formulation Tri-Solfen® containing two local anaesthetics (lignocaine and bupivacaine), adrenaline and an antiseptic (cetrimide) in a gel formulation was developed for pain relief in sheep undergoing surgical husbandry procedures in Australia. Recently, TS therapy was found to reduce suffering and enhance recovery in cattle and buffalo with oral and skin lesions due to foot-and-mouth disease (FMD) virus infection. It was noted that TS has a low pH and is potentially viricidal, potentially aiding disease control.

Methods: One-month-old lambs (n=14), naturally infected with orf, were recruited from a farm during a natural outbreak of the disease. The animals were selected at the early stages of the infection and randomly divided into two cohorts: Group A (n=11) treated with the topical wound gel formulation (TS); and Group B (n=3) an untreated control group. Swabs were obtained before treatment (T0) and on days one (T1), 3 (T2) and 5 (T3) post-treatment, then submitted to direct DNA extraction with real-time PCR quantification, plus incubation with primary tissue cultures from ovine skin fibroblasts (OSF) and T-immortalized goat embryonic fibroblasts (TIGEF).

Results: Although no significant differences were found in the clinical progression of the lesions and PCR quantification (p=0.722) between these small cohorts, there was a significant difference (p<0.05) in reduction in infective viral load between the groups when assessed in OSF cell cultures between T0 and T3.

Conclusion: These preliminary findings suggest that treatment of early stage lesions with this TS may reduce the infective viral load present in orf lesions.

Keywords: contagious ecthyma; local therapy; sheep; wound formulation.

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Conflict of interest statement

The abstract of this paper was presented at the International Congress on the breeding of sheep and goats. A hybrid conference that was held in Bonn, as an oral presentation with interim findings. The authors report no conflicts of interest in this work.

Figures

Figure 1
Figure 1
Orf viral load in ovine skin fibroblasts (OSF) incubated with swab samples from naturally infected lambs obtained from control and treated groups. Data shown are the differences in viral load from T0 to T3 in control and treated animals (*p< 0.05).
Figure 2
Figure 2
Orf viral load in T-immortalized goat fibroblasts (TIGEF) incubated with samples from naturally infected lambs obtained from control and treated groups. Data shown are the differences in viral load from T0 to T3 in control and treated animals (p> 0.05).
See this image and copyright information in PMC

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