Development and preclinical evaluation of equine-derived hyperimmune serum against SARS-CoV-2 infection in K-18 hACE2 transgenic (Tg) mice.

This study aimed to develop an equine-derived hyperimmune serum against SARS-CoV-2 and evaluate its efficacy as a potential immunotherapy tool for the treatment of known and potential variants of COVID-19 in preclinical trials. The novelty of this study is the whole virus and ALUM gel adjuvant formula. The horses were immunized using a whole inactivated SARS-CoV-2 antigen, and the final purified hyperimmune serum showed high plaque reduction neutralization (PRNT 50) neutralizing titers. The efficacy of the hyperimmune serum was evaluated histopathologically and biochemically in the lungs, hearts, and serum of K18 hACE2 transgenic mice (n=45), which is an accepted model organism for SARS-CoV-2 studies and was challenged with live SARS-CoV-2. Serum treatment improved the general condition, resulting in lower levels of proinflammatory cytokines in the blood plasma, as well as reduced viral RNA titers in the lungs and hearts. Additionally, it reduced oxidative stress significantly and lessened the severity of interstitial pneumonia in the lungs when compared to infected positive controls. The study concluded that equine-derived anti-SARS-CoV-2 antibodies could be used for COVID-19 prevention and treatment, especially in the early stages of the disease and in combination with antiviral drugs and vaccines. This treatment will benefit special patient populations such as immunocompromised individuals, as specific antibodies against SARS-CoV-2 can neutralize the virus before it enters host cells. The rapid and cost-effective production of the serum allows for its availability during the acute phase of the disease, making it a critical intervention in preventing the spread of the disease and saving lives in new variants where a vaccine is not yet developed.

Molecular typing of equine papillomavirus and autovaccination to treat horses with cutaneous papillomatosis.

OBJECTIVE: The aim of this study was to evaluate formalin-inactivated autovaccination to treat cutaneous papillomatosis and to perform molecular typing of the papillomavirus in four horses (two foals, one 3-year-old filly and a 5-year-old stallion). METHODS: Histopathological slides of lesions were prepared and stained with haematoxylin and eosin (H&E) to establish a diagnosis that was based on observation koilocytosis, which is a pathognomonic cytopathic change that is associated with papillomatosis, using light microscopy. Polymerase chain reaction (PCR) and DNA sequencing were performed using the EPV-R and EPV-F primer set. RESULTS: In histopathological examination, koilocyte formation and occasional intranuclear viral inclusions were detected in the papillomas. A 334-base pair (bp) fragment of the E2 and L2 genes from the EPV genome was amplified using the EPV-R and EPV-F primer set. This fragment contained 215 bp from the E2 gene and 56 bp from the L2 gene; these were found to be 98.78% to 98.97% identical to the known EcPV type-1 sequence (AF498323). CONCLUSION: Three horses with cutaneous papillomatosis were administered two doses of a formalin-inactivated preparation of papillomatous lesions at 7-day intervals. The papillomatous lesions were observed to decrease gradually 1 week after the last vaccination, and all warts had resolved within 2-3 weeks. One horse with cutaneous papillomatosis was left as an unvaccinated control, and no changes to the lesions were noted. To the best of our knowledge, this is the first report of EcPV type-1 infection, autovaccine preparation and molecular typing in Turkey.