Preliminary Study on the Efficacy of a Recombinant, Subunit SARS-CoV-2 Animal Vaccine against Virulent SARS-CoV-2 Challenge in Cats.

The objective of this work was to evaluate the safety and efficacy of a recombinant, subunit SARS-CoV-2 animal vaccine in cats against virulent SARS-CoV-2 challenge. Two groups of cats were immunized with two doses of either a recombinant SARS-CoV-2 spike protein vaccine or a placebo, administered three weeks apart. Seven weeks after the second vaccination, both groups of cats were challenged with SARS-CoV-2 via the intranasal and oral routes simultaneously. Animals were monitored for 14 days post-infection for clinical signs and viral shedding before being humanely euthanized and evaluated for macroscopic and microscopic lesions. The recombinant SARS-CoV-2 spike protein subunit vaccine induced strong serologic responses post-vaccination and significantly increased neutralizing antibody responses post-challenge. A significant difference in nasal and oral viral shedding, with significantly reduced virus load (detected using RT-qPCR) was observed in vaccinates compared to mock-vaccinated controls. Duration of nasal, oral, and rectal viral shedding was also significantly reduced in vaccinates compared to controls. No differences in histopathological lesion scores were noted between the two groups. Our findings support the safety and efficacy of the recombinant spike protein-based SARS-CoV-2 vaccine which induced high levels of neutralizing antibodies and reduced nasal, oral, and rectal viral shedding, indicating that this vaccine will be efficacious as a COVID-19 vaccine for domestic cats.

Experimental veterinary SARS-CoV-2 vaccine cross neutralization of the Delta (B.1.617.2) variant virus in cats.

SARS-CoV-2 has exhibited varying pathogenesis in a variety of Mammalia family's including Canidae, Mustelidae, Hominidae, Cervidae, Hyaenidae, and Felidae. Novel SARS-CoV-2 variants characterized by spike protein mutations have recently resulted in clinical and epidemiological concerns, as they potentially have increased infectious rates, increased transmission, or reduced neutralization by antibodies produced via vaccination. Many variants have been identified at this time, but the variant of continuing concern has been the Delta variant (B.1.617.2), due to its increased transmissibility and infectious rate. Felines vaccinated using an experimental SARS-CoV-2 spike protein-based veterinary vaccine mounted a robust immune response to the SARS-CoV-2 spike protein. Using a reporter virus particle system and feline serum, we have verified that vaccinated felines produce antibodies that neutralize the SARS-CoV-2 Wuhan strain and variant B.1.617.2 at comparable levels.

Vaccination with an inactivated canine influenza H3N2 virus vaccine is safe and elicits an immune response in cats.

OBJECTIVES: The aim of this study was to evaluate safety and seroconversion when an inactivated H3N2 canine influenza virus (CIV) vaccine was administered to cats. METHODS: Twenty 7-8-week-old seronegative cats were randomly assigned to two groups of 10 animals each. Cats in treatment group T01 were subcutaneously administered two doses of an adjuvanted placebo 3 weeks apart to serve as non-immunized controls. Cats in treatment group T02 were subcutaneously administered with two doses of H3N2 CIV vaccine at 3 weeks apart. All animals were actively monitored for 5 days after each injection for local and systemic reactions. Tympanic temperatures were recorded the day before and 5 days after each vaccination. Blood samples for serology were collected prior to each vaccination (days -1 and 20), and 7 and 14 days post-second vaccination. RESULTS: Minor vocalization was observed in both control and vaccinated animals after the first and second dose administration. The only injection site reaction observed was mild swelling in one control cat, which resolved within 24 h. Transient fevers (39.5-39.7°C) that resolved within 24 h post-injection were observed in both treatment groups (T01 = 3/10 and T02 = 5/10). All vaccinated, but no control, animals successfully seroconverted within 14 days of second vaccination, with H3N2 CIV-specific hemagglutination inhibition (HAI) titers ranging from 32 to 128. CONCLUSIONS AND RELEVANCE: Cats vaccinated subcutaneously with an inactivated H3N2 CIV vaccine had similar rates of adverse events post-vaccination as the control group. Increased HAI titers provided evidence of post-vaccination seroconversion with the H3N2 CIV-vaccinated group.

Early diagnosis and successful treatment of a patient with transfusion-associated GVHD with autologous peripheral blood progenitor cell transplantation.

BACKGROUND: Transfusion-associated GVHD (TA-GVHD) is an uncommon complication of blood transfusion. Diagnosis of TA-GVHD is difficult, and it is usually rapidly fatal. There are few documented sur- vivors of TA-GVHD. CASE REPORT: A 61-year-old woman with chronic lymphocytic leukemia (CLL) was treated with fludarabine followed by combination chemotherapy and high-dose radioimmunotherapy and peripheral blood progenitor cell (PBPC) rescue. She was transfused with nonirradiated blood components at an outside hospital and presented 10 days later with rash, elevated liver enzymes, and progressive pancytopenia. Skin biopsy was consistent with GVHD, and HLA typing of lymphocytes from the patient demonstrated mixed chimerism. The patient was treated with solumedrol and cyclosporin A, followed by high-dose cyclophosphamide and antithymocyte globulin and autologous PBPC infusion. She had rapid engraftment, resolution of skin rash, and normalization of liver function abnormalities. She is in good health with normal blood counts and no evidence of CLL 34 months after transplantation. CONCLUSION: TA-GVHD occurs in the setting of an immunocompromised recipient receiving nonirradiated blood components. A typical presentation includes skin rash, liver function abnormalities, and pancytopenia. Demonstration of mixed chimerism by HLA typing facilitated diagnosis in this patient. High-dose immunosuppression, facilitated by the availability of autologous PBPCs, resulted in a successful outcome.