{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"institution":[{"name":"medRxiv"}],"indexed":{"date-parts":[[2026,1,24]],"date-time":"2026-01-24T03:39:41Z","timestamp":1769225981164,"version":"3.49.0"},"posted":{"date-parts":[[2026,1,19]]},"group-title":"Infectious Diseases (except HIV\/AIDS)","reference-count":28,"publisher":"openRxiv","license":[{"start":{"date-parts":[[2026,1,19]],"date-time":"2026-01-19T00:00:00Z","timestamp":1768780800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"accepted":{"date-parts":[[2026,1,19]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                <jats:p>\n                  Malaria remains a major public health concern in Cameroon, with\n                  <jats:italic>Plasmodium falciparum<\/jats:italic>\n                  responsible for most morbidity and mortality, particularly among children under five. In response to rising cases, Cameroon began implementing the RTS,S\/AS01 malaria vaccine in early 2024. Given the vaccine\u2019s strain-specific efficacy, understanding antigenic diversity and complexity of infection (COI) is critical for evaluating long-term impact. We analyzed 100\n                  <jats:italic>P. falciparum<\/jats:italic>\n                  \u2013positive dried blood spots collected in Mapoussere, Kaele Health District (2022\u20132023). Using the 4CAST amplicon sequencing assay, we targeted four genes:\n                  <jats:italic>csp<\/jats:italic>\n                  (circumsporozoite protein),\n                  <jats:italic>ama<\/jats:italic>\n                  (apical membrane antigen 1),\n                  <jats:italic>sera2<\/jats:italic>\n                  (serine repeat antigen 2), and\n                  <jats:italic>trap<\/jats:italic>\n                  (thrombospondin-related anonymous protein). Haplotypes were identified using SeekDeep, and diversity metrics including heterozygosity (He), nucleotide diversity (\u03c0), and selection statistics (Tajima\u2019s D, Fu and Li\u2019s D*, F*) were computed. We successfully genotyped\n                  <jats:italic>csp<\/jats:italic>\n                  in 35% of samples, identifying 22 haplotypes (He = 0.908; \u03c0 = 0.021). The vaccine-matched haplotype was present in 20% of genotyped infections. The T cell TH2 and TH3 epitopes of\n                  <jats:italic>csp<\/jats:italic>\n                  showed signs of balancing selection. Both\n                  <jats:italic>ama<\/jats:italic>\n                  and\n                  <jats:italic>sera2<\/jats:italic>\n                  exhibited higher genotyping success and diversity, with\n                  <jats:italic>ama<\/jats:italic>\n                  showing significant Tajima\u2019s D values. COI was highest for\n                  <jats:italic>ama<\/jats:italic>\n                  (mean COI = 2.8), followed by\n                  <jats:italic>sera2<\/jats:italic>\n                  (2.1),\n                  <jats:italic>csp<\/jats:italic>\n                  (1.3), and\n                  <jats:italic>trap<\/jats:italic>\n                  (1.2). This study provides a baseline of\n                  <jats:italic>P. falciparum<\/jats:italic>\n                  antigenic diversity and COI in a vaccine-targeted region. The presence of vaccine-matched strains and high diversity in TH2\/TH3 epitopes in\n                  <jats:italic>csp<\/jats:italic>\n                  may influence vaccine efficacy. Continued molecular surveillance is essential to monitor antigenic shifts and guide future strategies.\n                <\/jats:p>","DOI":"10.64898\/2026.01.17.26344325","type":"posted-content","created":{"date-parts":[[2026,1,19]],"date-time":"2026-01-19T22:40:13Z","timestamp":1768862413000},"source":"Crossref","is-referenced-by-count":0,"title":["Complexity of Infection and\n                  <i>Plasmodium falciparum<\/i>\n                  Circumsporozoite Protein Diversity Prior to Malaria Vaccine Implementation in Kael\u00e9 Health District, Cameroon, 2022-2023"],"prefix":"10.64898","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-1112-6376","authenticated-orcid":false,"given":"Innocent M.","family":"Ali","sequence":"first","affiliation":[{"name":"Department of Biochemistry, Faculty of Science, Universit\u00e9 de Dschang, Dschang, West Region, Cameroon"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Brenda Vasquez","family":"Martinez","sequence":"additional","affiliation":[{"name":"Institute for Global Health and Infectious Diseases, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Valery P. K.","family":"Tchuenkam","sequence":"additional","affiliation":[{"name":"Department of Biochemistry, Faculty of Science, Universit\u00e9 de Dschang, Dschang, West Region, Cameroon"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0001-6430-608X","authenticated-orcid":false,"given":"Jacob M.","family":"Sadler","sequence":"additional","affiliation":[{"name":"Institute for Global Health and Infectious Diseases, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Catherine C.","family":"Gorman","sequence":"additional","affiliation":[{"name":"Institute for Global Health and Infectious Diseases, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0607-0881","authenticated-orcid":false,"given":"Sandrine E.","family":"Nsango","sequence":"additional","affiliation":[{"name":"Centre Pasteur du Cameroun, Yaound\u00e9, Cameroon"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Voundi Voundi","family":"Junior","sequence":"additional","affiliation":[{"name":"National Malaria Control Program, Ministry of Public Health, Cameroon"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ateba Joel","family":"Marcellin","sequence":"additional","affiliation":[{"name":"National Malaria Control Program, Ministry of Public Health, Cameroon"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Grace Yimga","family":"Wanda","sequence":"additional","affiliation":[{"name":"Department of Biochemistry, Faculty of Science, Universit\u00e9 de Dschang, Dschang, West Region, Cameroon"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6899-8204","authenticated-orcid":false,"given":"Jeffrey A.","family":"Bailey","sequence":"additional","affiliation":[{"name":"Department of Pathology and Laboratory Medicine, Brown University, Providence, RI, United States of America"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Rhoel R.","family":"Dinglasan","sequence":"additional","affiliation":[{"name":"Department of Infectious Diseases & Immunology and the Emerging Pathogens Institute, College of Veterinary Medicine, University of Florida, Gainesville, Florida, United States of America"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jessica T.","family":"Lin","sequence":"additional","affiliation":[{"name":"Department of Biochemistry, Faculty of Science, Universit\u00e9 de Dschang, Dschang, West Region, Cameroon"},{"name":"Division of Infectious Diseases, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0591-0850","authenticated-orcid":false,"given":"Jonathan J.","family":"Juliano","sequence":"additional","affiliation":[{"name":"Department of Biochemistry, Faculty of Science, Universit\u00e9 de Dschang, Dschang, West Region, Cameroon"},{"name":"Division of Infectious Diseases, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America"},{"name":"Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"54368","reference":[{"key":"2026012108550923000_2026.01.17.26344325v1.1","doi-asserted-by":"crossref","first-page":"1075755","DOI":"10.3389\/fmala.2023.1075755","article-title":"Genomic analysis of Plasmodium falciparum isolates across different altitudinal zones along the slope of Mount Cameroon","volume":"1","year":"2023","journal-title":"Front. Malar"},{"key":"2026012108550923000_2026.01.17.26344325v1.2","doi-asserted-by":"publisher","DOI":"10.1371\/journal.pone.0062427"},{"key":"2026012108550923000_2026.01.17.26344325v1.3","doi-asserted-by":"publisher","DOI":"10.1186\/1475-2875-13-233"},{"key":"2026012108550923000_2026.01.17.26344325v1.4","doi-asserted-by":"crossref","first-page":"428","DOI":"10.1080\/20477724.2021.1953686","article-title":"High genetic complexity but low relatedness in infections from Western Savannah Highlands and coastal equatorial Lowlands of Cameroon","volume":"116","year":"2022","journal-title":"Pathog Glob Health"},{"key":"2026012108550923000_2026.01.17.26344325v1.5","doi-asserted-by":"publisher","DOI":"10.1093\/infdis\/jis329"},{"key":"2026012108550923000_2026.01.17.26344325v1.6","doi-asserted-by":"publisher","DOI":"10.1371\/journal.pone.0008497"},{"key":"2026012108550923000_2026.01.17.26344325v1.7","doi-asserted-by":"publisher","DOI":"10.3390\/tropicalmed8080390"},{"key":"2026012108550923000_2026.01.17.26344325v1.8","first-page":"1","article-title":"Genetic polymorphism of msp2 in Plasmodium falciparum isolates among asymptomatic malaria infections from two ecological settings in Cameroon","volume":"24","year":"2025","journal-title":"Malaria Journal"},{"key":"2026012108550923000_2026.01.17.26344325v1.9","doi-asserted-by":"crossref","first-page":"10764","DOI":"10.3390\/ijms262110764","article-title":"Targeted Sequencing Identifies SNPs Associated with Antimalarial Drug Resistance and the CSP Vaccine Antigen in Plasmodium falciparum from Southwest Cameroon","volume":"26","year":"2025","journal-title":"Int. J. Mol. Sci"},{"key":"2026012108550923000_2026.01.17.26344325v1.10","doi-asserted-by":"crossref","first-page":"e0330480","DOI":"10.1371\/journal.pone.0330480","article-title":"Prevalence of asymptomatic non-falciparum and falciparum malaria in the 2014-15 Rwanda Demographic Health Survey","volume":"20","year":"2025","journal-title":"PLoS One"},{"key":"2026012108550923000_2026.01.17.26344325v1.11","doi-asserted-by":"publisher","DOI":"10.1093\/nar\/gkx1201"},{"key":"2026012108550923000_2026.01.17.26344325v1.12","doi-asserted-by":"crossref","first-page":"147956","DOI":"10.1016\/j.gene.2023.147956","article-title":"Genetic diversity and natural selection of apical membrane antigen-1 (ama-1) in Cameroonian Plasmodium falciparum isolates","volume":"894","year":"2024","journal-title":"Gene"},{"key":"2026012108550923000_2026.01.17.26344325v1.13","doi-asserted-by":"crossref","first-page":"148744","DOI":"10.1016\/j.gene.2024.148744","article-title":"Genetic analysis of the circumsporozoite gene in Plasmodium falciparum isolates from Cameroon: Implications for efficacy and deployment of RTS,S\/AS01 vaccine","volume":"927","year":"2024","journal-title":"Gene"},{"key":"2026012108550923000_2026.01.17.26344325v1.14","doi-asserted-by":"publisher","DOI":"10.1111\/1755-0998.13622"},{"key":"2026012108550923000_2026.01.17.26344325v1.15","unstructured":"National Malaria Control Program, Cameroon (n.d.). Available at: https:\/\/pnlp.cm"},{"key":"2026012108550923000_2026.01.17.26344325v1.16","doi-asserted-by":"crossref","first-page":"e1009801","DOI":"10.1371\/journal.pcbi.1009801","article-title":"Global diversity and balancing selection of 23 leading Plasmodium falciparum candidate vaccine antigens","volume":"18","year":"2022","journal-title":"PLoS Comput Biol"},{"key":"2026012108550923000_2026.01.17.26344325v1.17","doi-asserted-by":"publisher","DOI":"10.3390\/vaccines12040346"},{"key":"2026012108550923000_2026.01.17.26344325v1.18","doi-asserted-by":"publisher","DOI":"10.1056\/NEJMoa1505819"},{"key":"2026012108550923000_2026.01.17.26344325v1.19","doi-asserted-by":"publisher","DOI":"10.1128\/IAI.00576-10"},{"key":"2026012108550923000_2026.01.17.26344325v1.20","unstructured":"ReliefWeb (n.d.). Available at: https:\/\/reliefweb.int\/report\/cameroon\/one-year-anniversary-malaria-vaccine-rollout-underscores-remarkable-progress-offers-new-data-potential-impact (Accessed October 4, 2025)."},{"key":"2026012108550923000_2026.01.17.26344325v1.21","doi-asserted-by":"publisher","DOI":"10.1093\/molbev\/msx248"},{"key":"2026012108550923000_2026.01.17.26344325v1.22","doi-asserted-by":"publisher","DOI":"10.1016\/S0140-6736(15)60721-8"},{"key":"2026012108550923000_2026.01.17.26344325v1.23","doi-asserted-by":"publisher","DOI":"10.1056\/NEJMoa1102287"},{"key":"2026012108550923000_2026.01.17.26344325v1.24","first-page":"1509261","article-title":"Application of a new highly multiplexed amplicon sequencing tool to evaluate antimalarial resistance and relatedness in individual and pooled samples from Dschang, Cameroon","volume":"3","year":"2024","journal-title":"Front Parasitol"},{"key":"2026012108550923000_2026.01.17.26344325v1.25","doi-asserted-by":"publisher","DOI":"10.4269\/ajtmh.2012.11-0433"},{"key":"2026012108550923000_2026.01.17.26344325v1.26","doi-asserted-by":"publisher","DOI":"10.1093\/molbev\/msaa225"},{"key":"2026012108550923000_2026.01.17.26344325v1.27","doi-asserted-by":"publisher","DOI":"10.1016\/j.ijpara.2006.09.001"},{"key":"2026012108550923000_2026.01.17.26344325v1.28","unstructured":"World Health Organization (2024). World Malaria Report 2024."}],"container-title":[],"original-title":[],"link":[{"URL":"https:\/\/syndication.highwire.org\/content\/doi\/10.64898\/2026.01.17.26344325","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,1,21]],"date-time":"2026-01-21T16:55:21Z","timestamp":1769014521000},"score":1,"resource":{"primary":{"URL":"http:\/\/medrxiv.org\/lookup\/doi\/10.64898\/2026.01.17.26344325"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,1,19]]},"references-count":28,"URL":"https:\/\/doi.org\/10.64898\/2026.01.17.26344325","relation":{},"subject":[],"published":{"date-parts":[[2026,1,19]]},"subtype":"preprint"}}