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Human metapneumovirus (HMPV) is a common virus associated with acute respiratory distress syndrome in pediatric patients. There are no HMPV vaccines or therapeutics that have been approved for prevention or treatment. In this study, we constructed a novel recombinant influenza virus carrying partial HMPV fusion protein (HMPV-F), termed rFLU-HMPV/F-NS, utilizing reverse genetics, which contained (HMPV-F) in the background of NS segments of influenza virus A/PuertoRico/8/34(PR8). The morphological characteristics of rFLU-HMPV/F-NS were consistent with the wild-type flu virus. Additionally, immunofluorescence results showed that fusion proteins in the chimeric rFLU-HMPV/F-NS could work well, and the virus could be stably passaged in SPF chicken embryos. Furthermore, intranasal immunization with rFLU-HMPV/F-NS in BALB/c mice induced robust humoral, mucosal and Th1-type dominant cellular immune responses in vivo. More importantly, we discovered that rFLU-HMPV/F-NS afforded significant protective efficacy against the wild-type HMPV and influenza virus challenge, with significantly attenuated pathological changes and reduced viral titers in the lung tissues of immunized mice. Collectively, these findings demonstrated that chimeric recombinant rFLU-HMPV/F-NS as a promising HMPV candidate vaccine has potentials for the development of HMPV vaccine.

Objective: Smallpox, a severe infectious disease caused by the smallpox virus, causes a death rate as high as 30% within 15-20 days after infection. Therefore, development of anti-Smallpox product as a strategic reserve is urgently needed. Methods: We prepared and tested pepsin-digested F(ab')2 fragments of serum IgG from horses. Results: Transmission electron microscopy indicated that the purified virus showed morphology consistent with VVTT. The titer was above 1.0 × 107 PFU/mL. The purity of the antigen exceeded 90%, according to HPLC. After purification and cleavage, the yield of the purified product F(ab')2 was approximately 1.3%, its purity exceeded 90%, and the neutralizing antibody titer exceeded 1:3200. F(ab')2 fragments had good preventive and therapeutic effects in mice at antibody doses of 5.2 mg/mL and 2.6 mg/mL. The viral loads of the drug-treated mice were suppressed to varying degrees, and the higher dose groups (5.2 and 2.6 mg/mL) showed a 2-3 fold lower viral load than that in the control group. Conclusion: A process for producing equine immunoglobulin F(ab')2 against VVTT was established. The prepared horse anti-smallpox immunoglobulin product had good neutralizing antibody effects on VVTT. The highly purified preparation may serve as a potential candidate for smallpox treatment. [ABSTRACT FROM AUTHOR]

Human metapneumovirus (HMPV) is a leading cause of acute respiratory tract infections in infants and children. Currently, no approved HMPV vaccine is available. We developed a novel recombinant influenza virus, which carried partial HMPV F protein (HMPV-F) epitopes, utilizing reverse genetics. The novel single-stranded RNA virus, termed rFLU-HMPV/F-NA, was synthesized in the neuraminidase (NA) fragment of influenza virus A/PuertoRico/8/34 (PR8). The morphological characteristics of rFLU-HMPV/F-NA were consistent with the wild-type flu virus. The virus could passage in specific pathogen-free (SPF) chicken embryos for at least five consecutive generations with haemagglutinin (HA) titres of 28–9 or 8–9LogTCID50/mL. BALB/c mice were intranasally immunized at 21-day intervals with 104 TCID50 (low-dose group) or 106 TCID50 (high-dose group) rFLU-HMPV/F-NA, and PBS or PR8 vaccine was used for the control group. rFLU-HMPV/F-NA induced robust humoral, mucosal, and cellular immune responses in vivo in a dose-dependent manner. More importantly, wt clinical HMPV isolate challenge studies showed that rFLU-HMPV/F-NA provided significant immune protection against HMPV infection compared to the PBS or PR8 vaccine control group, as shown by improved histopathological changes and reduced viral titres in the lungs of immunized mice post-challenge. These findings demonstrate that rFLU-HMPV/F-NA has potential as a promising HMPV candidate vaccine and warrants further investigation into its control of HMPV infection. [ABSTRACT FROM AUTHOR]