Stability of Bas-Congo virus neutralising antibodies in serum samples during long-term storage—Authors’ reply
Authors: Yannick Munyeku-Bazitama, Patient Okitale-Talunda, Takanari Hattori, Takeshi Saito, Boniface Pongombo Lombe, Hiroko Miyamoto, Akina Mori-Kajihara, Masahiro Kajihara, Agathe Bikupe Nkoy, Augustin Tshibwabwa Twabela, Justin Masumu, Steve Ahuka-Mundeke, Jean-Jacques Muyembe-Tamfum, Manabu Igarashi, Eun-sil Park, Shigeru Morikawa, Sheila Makiala-Mandanda, Ayato Takada
Journal: The Lancet Microbe (2024)

We thank Lifeng Zhao and colleagues for raising potential issues in our Article1Munyeku-Bazitama Y Okitale-Talunda P Hattori T et al.Seroprevalence of Bas-Congo virus in Mangala, Democratic Republic of the Congo: a population-based cross-sectional study.Lancet Microbe. 2024; 5: e529-e537Summary Full Text Full Text PDF PubMed Scopus (3) Google Scholar with respect to the stability of Bas-Congo virus (BASV) neutralising antibodies. With regard to the first point, we indeed used 284 archived samples collected as part of SARS-CoV-2 population-based seroepidemiological surveys conducted, in 2021, in Kinshasa2Munyeku-Bazitama Y Folefack GT Yambayamba MK et al.High SARS-CoV-2 seroprevalence after second COVID-19 wave (October 2020–April 2021), Democratic Republic of the Congo.Emerg Infect Dis. 2023; 29: 89-97Crossref PubMed Scopus (7) Google Scholar and, in 2022, in Matadi.3Munyeku-Bazitama Y Okitale-Talunda P Mpingabo-Ilunga P et al.High severe acute respiratory syndrome coronavirus 2 antibody prevalence after the third epidemic wave (May–October 2021) in Matadi, Democratic Republic of the Congo.Open Forum Infect Dis. 2023; 10: ofad023Crossref PubMed Google Scholar For samples collected in Kinshasa, venous blood was collected in red-topped plain tubes and transported at 4°C in cool boxes to the National Institute for Biomedical Research (French acronym: INRB) on the same day. At INRB, blood was processed to obtain serum. Serum samples were aliquoted in 2-mL cryotubes (two aliquots of 1 mL each) and stored at −20°C for subsequent analyses. Samples collected in Matadi and Mangala were transported at 4°C in cool boxes to the nearest health facility or public health provincial laboratory and processed to obtain serum and make aliquots.1Munyeku-Bazitama Y Okitale-Talunda P Hattori T et al.Seroprevalence of Bas-Congo virus in Mangala, Democratic Republic of the Congo: a population-based cross-sectional study.Lancet Microbe. 2024; 5: e529-e537Summary Full Text Full Text PDF PubMed Scopus (3) Google Scholar,3Munyeku-Bazitama Y Okitale-Talunda P Mpingabo-Ilunga P et al.High severe acute respiratory syndrome coronavirus 2 antibody prevalence after the third epidemic wave (May–October 2021) in Matadi, Democratic Republic of the Congo.Open Forum Infect Dis. 2023; 10: ofad023Crossref PubMed Google Scholar Aliquots were transferred within 24 h in portable freezers (−20°C) to INRB.1Munyeku-Bazitama Y Okitale-Talunda P Hattori T et al.Seroprevalence of Bas-Congo virus in Mangala, Democratic Republic of the Congo: a population-based cross-sectional study.Lancet Microbe. 2024; 5: e529-e537Summary Full Text Full Text PDF PubMed Scopus (3) Google Scholar, 2Munyeku-Bazitama Y Folefack GT Yambayamba MK et al.High SARS-CoV-2 seroprevalence after second COVID-19 wave (October 2020–April 2021), Democratic Republic of the Congo.Emerg Infect Dis. 2023; 29: 89-97Crossref PubMed Scopus (7) Google Scholar, 3Munyeku-Bazitama Y Okitale-Talunda P Mpingabo-Ilunga P et al.High severe acute respiratory syndrome coronavirus 2 antibody prevalence after the third epidemic wave (May–October 2021) in Matadi, Democratic Republic of the Congo.Open Forum Infect Dis. 2023; 10: ofad023Crossref PubMed Google Scholar For all collected samples, one aliquot was used for analyses related to the primary study and the remaining one was stored at −80°C for future use. The samples were not subjected to multiple freeze–thaw cycles before this study. With regard to the samples transported to Japan, the unused stored aliquot was thawed once, and 100 μL of serum was transferred to 1·5-mL cryotubes and transported by air with ice packs to the Hokkaido University International Institute for Zoonosis Control (HU-IIZC) within 48 h (temperature on arrival, 0–4°C). Samples were transferred under a Memorandum of Understanding signed between INRB and HU-IIZC and a specific Material Transfer Agreement. We appreciate Lifeng Zhao and colleagues' suggestion on assessing the stability of BASV neutralising antibodies; however, no relevant concerns were noted regarding the storage conditions that might affect the activities of BASV neutralising antibodies. We declare no competing interests. Stability of Bas-Congo virus neutralising antibodies in serum samples during long-term storageSeroprevalence of Bas-Congo virus in Mangala, Democratic Republic of the Congo: a population-based cross-sectional study