Identification of Torquetenovirus Species in Patients with Kawasaki Disease Using a Newly Developed Species-Specific PCR Method.

A next-generation sequencing (NGS) study identified a very high viral load of Torquetenovirus (TTV) in KD patients. We aimed to evaluate the feasibility of a newly developed quantitative species-specific TTV-PCR (ssTTV-PCR) method to identify the etiology of KD. We applied ssTTV-PCR to samples collected from 11 KD patients and 22 matched control subjects who participated in our previous prospective study. We used the NGS dataset from the previous study to validate ssTTV-PCR. The TTV loads in whole blood and nasopharyngeal aspirates correlated highly (Spearman's R = 0.8931, p < 0.0001, n = 33), supporting the validity of ssTTV-PCR. The ssTTV-PCR and NGS results were largely consistent. However, inconsistencies occurred when ssTTV-PCR was more sensitive than NGS, when the PCR primer sequences mismatched the viral sequences in the participants, and when the NGS quality score was low. Interpretation of NGS requires complex procedures. ssTTV-PCR is more sensitive than NGS but may fail to detect a fast-evolving TTV species. It would be prudent to update primer sets using NGS data. With this precaution, ssTTV-PCR can be used reliably in a future large-scale etiological study for KD.

A case of COVID-19-associated fulminant myocarditis due to SARS-CoV-2 omicron BA.2 sub-lineage in an unvaccinated female.

COVID-19-associated myocarditis can be a lethal complication in previous variants, but it is not well understood in the Omicron variant. We present an unvaccinated case of COVID-19-associated fulminant myocarditis due to the Omicron BA.2 sub-lineage requiring mechanical circulatory support (MCS). A 66-year-old female without vaccination against SARS-CoV-2 was hospitalized due to COVID-19. On the next day, she was transferred to our hospital due to the development of fulminant myocarditis. After arrival, she was treated with Impella CP and venoarterial extracorporeal membrane oxygenation due to unstable hemodynamics. In addition to MCS, we treated her with inotropes, methylprednisolone, tocilizumab, and remdesivir. Left ventricular contraction gradually improved, and MCS was removed on day 8. Endomyocardial biopsy showed mild interstitial infiltration of CD3+-T lymphocytes and CD68+-macrophages with no remarkable necrosis or fibrosis. This case showed similar histological characteristics to COVID-19-associated myocarditis before the Omicron variant. The vaccination against the Omicron variant should be considered to prevent the development of severe illness, including fulminant myocarditis. Learning objective: Although the Omicron variant is thought to be generally less severe, COVID-19-associated fulminant myocarditis, as in this case, can occur. The vaccination against the Omicron variant should be considered to prevent from developing severe illness.