Middle East respiratory syndrome coronavirus (MERS-CoV) causes severe respiratory disease in humans, with a case fatality rate of approximately 35%, thus posing a considerable threat to public health. A lack of approved vaccines or antivirals currently constitutes a barrier for controlling disease outbreaks and spread. In this study, we generated a replication-defective recombinant vesicular stomatitis virus expressing the MERS-CoV spike (S) protein (VSV/MERS). Uncleaved and cleaved S proteins were detected in VSV/MERS by western blotting. And VSV/MERS specifically transduced cells expressing human dipeptidyl peptidase 4, a receptor for MERS-CoV. To investigate the immunogenicity of VSV/MERS, mice were immunized intramuscularly with VSV/MERS and alum adjuvant. MERS-CoV S-specific IgG was detected in serum samples from immunized mice. These antibodies inhibited MERS entry in vitro, suggesting a protective efficacy of VSV/MERS immunity. The data demonstrate that VSV/MERS has potent immunogenicity and could serve as a novel potential vaccine platform for MERS in dromedary camels and human.

A 7-year-old, spayed female, domestic short hair cat showed signs of a 2-week history of chronic anorexia, depression, and severe weight loss. Upon physical examination, pyrexia, mild gingivitis, and pale mucus membranes were noted. Laboratory analysis revealed normocytic normochromic non-regenerative anemia, severe thrombocytopenia, and hypergammaglobulinemia. Serum protein electrophoresis revealed the presence of elevated alpha-2 fraction within the globulin concentration. Based on history, clinical signs, and laboratory results, systemic viral infection was strongly suspected. Reverse transcriptase polymerase chain reaction identified the presence of feline immunodeficiency virus (FIV) in the serum. Furthermore, gene sequencing revealed the virus as FIV subtype A. Treatment with anti-retroviral agents, including azidothymidine (AZT) and recombinant human interferon-alpha, was continued for 4 weeks. However, the patient’s clinical condition deteriorated, resulting in death 1 month after initiation of treatment due to progressive renal failure. Necropsy and histopathology revealed hepatic and renal necrosis with hyper-cellular bone marrow mainly comprised of myeloid precursor cells. This case report is the first to describe phylogenetic subtyping, anti-retroviral combination treatment, and clinical outcomes in an FIV-infected cat in Korea. In addition, this report suggests that treatment should be initiated during the early phase of infection that could be effective for the virus.

The silkworm-baculovirus expression system has distinct advantages, such as a high yield and safe usage in vertebrates. Here, we report a novel strategy for the large-scale production of a classical swine fever virus (CSFV) envelope glycoprotein E2 in the larvae of a baculovirus-infected silkworm, Bombyx mori. We constructed a recombinant B. mori nucleopolyhedrovirus (BmNPV) that expressed recombinant polyhedra together with the N-terminal 179 amino acids of CSFV E2 (E2ΔC). BmNPV-E2ΔC-infected silkworm larvae expressed native polyhedrin and approximately 44-kDa fusion protein that was detected using both anti-polyhedrin and anti-CSFV E2 antibodies. Electron and confocal microscopy both demonstrated that the recombinant polyhedra contained both the fusion protein and native polyhedrin were morphologically normal and contained CSFV E2ΔC. The CSFV E2ΔC antigen produced in BmNPV-E2ΔC-infected silkworm larvae reached 0.68 mg per ml of hemolymph and 0.53 mg per larva at 6 days post-infection. Six-week-old female BALB/c mice that were immunized with the E2ΔC protein purified from solubilized recombinant polyhedraelicited CSFV E2 antibodies, which indicated that the CSFV E2ΔC protein from recombinant polyhedra was immunogenic. The virus neutralization test showed that the serum from mice that were treated with E2ΔC protein from recombinant polyhedra contained significant levels of virus neutralization activity. These results demonstrate that the present strategy can be used for the large-scale production of CSFV E2 antigen.