Antigenic Relatedness between Mannans from Coccidioides immitis and Coccidioides posadasii Spherules and Mycelia

Amanda R. Burnham-Marusich, Kathleen R. Zayac, John N. Galgiani, Lourdes Lewis, Thomas R. Kozel

Research output: Contribution to journalArticlepeer-review


Immunoassays for cell wall mannans that are excreted into serum and urine have been used as an aid in the diagnosis of many disseminated fungal infections, including coccidioidomycosis. Antigen-detection immunoassays are critically dependent on the detection of an analyte, such as mannan, by antibodies that are specific to the analyte. The goal of this study was to evaluate the extent of cross-reactivity of polyclonal antibodies raised against Coccidioides spp. Analysis of antigenic relatedness between mannans from C. posadasii and C. immitis spherules and mycelia showed complete relatedness when evaluated by the method of Archetti and Horsfall, which was originally used to study the antigenic relationships between Influenzae virus isolates. In a further effort to validate the suitability of the antigenic relatedness calculation methodology for polysaccharide antigens, we also applied the method of Archetti and Horsfall to published results that had previously identified the major capsular serotypes of Cryptococcus species. The results of this analysis showed that Archetti and Horsfall’s antigenic relatedness calculation correctly identified the major cryptococcal serotypes. Together, these results suggest that the method is applicable to polysaccharide antigens, and that immunoassays that detect Coccidioides mannans are likely to have good reactivity across Coccidioides species (inclusivity) due to the species’ high level of antigenic relatedness.

Original languageEnglish (US)
Article number89
JournalJournal of Fungi
Issue number2
StatePublished - Feb 2024


  • Coccidioides
  • Cryptococcus
  • antigen-detection immunoassay
  • antigenic relatedness
  • coccidioidomycosis
  • diagnostics
  • immunoassay
  • mannan

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Plant Science
  • Microbiology (medical)


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