Introduction: The first imported case of monkeypox (MPX) from the mainland of China was reported in September 2022. Herein, the study reports the isolation and characterization of MPX virus (MPXV) in this case.Methods: Clinical specimens including skin blister fluid, oropharyngeal and nasopharyngeal swabs, and blood were collected and inoculated onto Vero cells. The isolated virus was identified as MPXV using quantitative polymerase chain reaction (qPCR), cytopathic effects (CPEs), immunofluorescence assay (IFA) and transmission electron microscopy (TEM). Plaque assays were employed to quantify infectious plaque-forming units (PFUs). The plaque reduction neutralization test (PRNT) was developed to determine the neutralizing antibody (nAb) against MPXV.Results: MPXV replication was confirmed with qPCR. Typical CPEs were observed 48 h postincubation. The isolated virus was named MPXV-B.1-China-C-Tan-CQ01. IFA showed that MPXV reacted with serum of MPX case. Orthopoxvirus morphology was observed using TEM. The virus titer increased to >10 6 PFU/mL after three passages. The serum PRNT 50% neutralization titer (NT 50 ) was 35 for the MPX patient 6 days after symptom onset.Discussion: The study successfully isolated the first MPXV strain in the mainland of China, MPXV-B.1-China-C-Tan-CQ01. Infectious titration and PRNT methods have been developed. The study provides key resources and technical platforms for further research as well as anti-viral drug and vaccine development against MPX.
Background
Several COVID-19 vaccines are in widespread use in China. Few data exist on comparative immunogenicity of different COVID-19 vaccines given as booster doses. We aimed to assess neutralizing antibody levels raised by injectable and inhaled aerosolized recombinant adenovirus type 5 (Ad5)-vectored COVID-19 vaccine as a heterologous booster after an inactivated COVID-19 vaccine two-dose primary series.
Methods
Using an open-label prospective cohort design, we recruited 136 individuals who had received inactivated vaccine primary series followed by either injectable or inhaled Ad5-vectored vaccine and measured neutralizing antibody titers against ancestral SARS-CoV-2 virus and Omicron BA.1 and BA.5 variants. We also measured neutralizing antibody levels in convalescent sera from 39 patients who recovered from Omicron BA.2 infection.
Results
Six months after primary series vaccination, neutralizing immunity against ancestral SARS-CoV-2 was low and neutralizing immunity against Omicron (B.1.1.529) was lower. Boosting with Ad5-vectored vaccines induced a high immune response against ancestral SARS-CoV-2. Neutralizing responses against Omicron BA.5 were ≥ 80% lower than against ancestral SARS-CoV-2 in sera from prime-boost subjects and in convalescent sera from survivors of Omicron BA.2 infection. Inhaled aerosolized Ad5-vectored vaccine was associated with greater neutralizing titers than injectable Ad5-vectored vaccine against ancestral and Omicron SARS-CoV-2 variants.
Conclusions
These findings support the current strategy of heterologous boosting with injectable or inhaled Ad5-vectored SARS-CoV-2 vaccination of individuals primed with inactivated COVID-19 vaccine.
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