Evaluation of SARS-CoV-2 isolation in cell culture from nasal/nasopharyngeal swabs or saliva specimens of patients with COVID-19
Shunsuke Yazawa, Emiko Yamazaki, Yumiko Saga, Masae Itamochi, Noriko Inasaki, Takahisa Shimada, Kazunori Oishi, Hideki Tani
doi:10.21203/rs.3.rs-2676422/v1
It has been revealed that SARS-CoV-2 can be e ciently isolated from clinical specimens such as nasal/nasopharyngeal swabs or saliva in cultured cells. In this study, we examined the e ciency of viral isolation including SARS-CoV-2 mutant strains between nasal/nasopharyngeal swab or saliva specimens. Furthermore, we also examined the comparison of viral isolation rates by sample species using simulated specimens for COVID-19. As a result, it was found that the isolation e ciency of SARS-CoV-2 in the saliva specimens was signi cantly lower than that in the nasal/nasopharyngeal swab specimens. In order to determine which component of saliva is responsible for the lower isolation rate of saliva specimens, we tested the abilities of lactoferrin, amylase, cathelicidin, and mucin, which are considered to be abundant in saliva, to inhibit the infection of SARS-CoV-2 pseudotyped viruses (SARS-CoV-2pv). Lactoferrin and amylase were found to inhibit SARS-CoV-2pv infection. In conclusion, even if the same number of viral genome copies was detected by the real-time RT-PCR test, infection of SARS-CoV-2 present in saliva is thought to be inhibited by inhibitory factors such as lactoferrin and amylase, compared to nasal/nasopharyngeal swab specimens.
Declarations Ethical approval This study was performed in accordance with the Helsinki Declaration and was approved by the ethical review board of the Toyama Institute of Health (approval No.: R2-1). The need of informed consent was also waived by the ethical review board of the Toyama Institute of Health (approval No.: R2-1).
Con ict of interest We have no potential con icts of interest in relation to this work.
References
Griesemer, Evaluation of Specimen Types and Saliva Stabilization Solutions for SARS-CoV-2 Testing, J Clin Microbiol,
doi:10.1128/JCM.01418-20
Hu, Meng, Zhang, Xiang, Wang, The in vitro antiviral activity of lactoferrin against common human coronaviruses and SARS-CoV-2 is mediated by targeting the heparan sulfate coreceptor, Emerg Microbes Infect,
doi:10.1080/22221751.2021.1888660
Kobayashi-Sakamoto, Bovine lactoferrin increases the poly(I:C)-induced antiviral response in vitro, Biochem Cell Biol,
doi:10.1139/bcb-2021-0342
Lai, Identi ed human breast milk compositions effectively inhibit SARS-CoV-2 and variants infection and replication, iScience,
doi:10.1016/j.isci.2022.104136
Scola, Viral RNA load as determined by cell culture as a management tool for discharge of SARS-CoV-2 patients from infectious disease wards, Eur J Clin Microbiol Infect Dis,
doi:10.1007/s10096-020-03913-9
Tani, Evaluation of SARS-CoV-2 neutralizing antibodies using a vesicular stomatitis virus possessing SARS-CoV-2 spike protein, Virol J,
doi:10.1186/s12985-021-01490-7
Yamaguchi, Deguchi, Miyazaki, The effects of exercise in forest and urban environments on sympathetic nervous activity of normal young adults, J Int Med Res,
doi:10.1177/147323000603400204
Young, Viral Dynamics and Immune Correlates of Coronavirus Disease 2019 (COVID-19) Severity, Clin Infect Dis,
doi:10.1093/cid/ciaa1280
Zhang, An updated review of SARS-CoV-2 detection methods in the context of a novel coronavirus pandemic, Bioeng Transl Med,
doi:10.1002/btm2.10356