Related Experiment Video

Updated: Aug 12, 2026

Visualizing Non-lytic Exocytosis of Cryptococcus neoformans from Macrophages Using Digital Light Microscopy
10:02

Visualizing Non-lytic Exocytosis of Cryptococcus neoformans from Macrophages Using Digital Light Microscopy

Published on: October 21, 2014

Cryptococcus neoformans interactions with amoebae suggest an explanation for its virulence and intracellular

J N Steenbergen1, H A Shuman, A Casadevall

  • 1Department of Microbiology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.

Proceedings of the National Academy of Sciences of the United States of America
|December 14, 2001
PubMed

Insights

Cryptococcus neoformans (Cn) survives and replicates within amoebae, similar to its behavior in human macrophages. This suggests fungal virulence evolved from adaptations to environmental predators like amoebae.

Area of Science:

  • Microbiology
  • Pathogenesis
  • Mycology

Background:

  • Cryptococcus neoformans (Cn) is an environmental fungus causing meningitis in immunocompromised individuals.
  • Cn is a facultative intracellular pathogen that replicates within macrophages.
  • The evolution of Cn virulence remains poorly understood.

Purpose of the Study:

  • To investigate the hypothesis that Cn survival strategies within amoebae mirror those within macrophages.
  • To explore the role of amoebae as a potential environmental host for Cn.

Main Methods:

  • Microscopy to observe Cn-amoebae interactions.
  • Fungal and amoebae killing assays.
  • Phagocytosis assays.
  • Evaluation of acapsular and melanized strains, and phospholipase mutants.

Main Results:

  • Cn replicates within Acanthamoeba castellanii, leading to amoebal death.
  • Melanization protects Cn against amoebal killing, while an acapsular strain does not survive.
  • A phospholipase mutant showed reduced replication in amoebae.
  • Intracellular replication involved polysaccharide vesicle accumulation, similar to macrophage infections.

Conclusions:

  • Cn virulence factors for mammals also confer survival against amoebae.
  • Amoebae may serve as an environmental reservoir and training ground for Cn virulence.
  • This interaction provides an explanation for the broad host range of this pathogenic fungus.

More Related Videos

Macrophage Cholesterol Depletion and Its Effect on the Phagocytosis of Cryptococcus neoformans11:07

Macrophage Cholesterol Depletion and Its Effect on the Phagocytosis of Cryptococcus neoformans

Published on: December 19, 2014

Complementary Use of Microscopic Techniques and Fluorescence Reading in Studying Cryptococcus-Amoeba Interactions10:56

Complementary Use of Microscopic Techniques and Fluorescence Reading in Studying Cryptococcus-Amoeba Interactions

Published on: June 22, 2019

Related Concept Videos

Immune Surveillance by NK Cells and Phagocytes01:25

Immune Surveillance by NK Cells and Phagocytes

Immune surveillance is an integral part of the innate immune system, involving the continuous monitoring of peripheral tissues to detect and respond to pathogens, infected cells, or cancerous cells. This surveillance is conducted primarily by natural killer (NK) cells and phagocytes, which employ distinct but complementary mechanisms to identify and eliminate threats.
Natural Killer Cells: The Fast Responders
NK cells are large granular lymphocytes found in the blood and lymphatic system. These...
Fungal Phylum Microsporidia01:28

Fungal Phylum Microsporidia

Microsporidia are a group of obligate intracellular fungi that were initially classified as protists but were later reclassified based on phylogenetic, molecular, and structural evidence linking them to the Chytridiomycota. These unicellular, non-motile organisms are highly specialized parasites that infect a wide range of animal hosts, including humans. They have evolved extensive genomic and metabolic reductions, making them highly dependent on their hosts for survival.Morphology and Genomic...
Diversity of Protists II01:27

Diversity of Protists II

Alveolates are a group of organisms recognized by the presence of alveoli, which are cytoplasmic sacs located beneath the cell membrane. While their function remains uncertain, alveoli may help regulate water balance by controlling how much water enters and leaves the cell. In dinoflagellates, these structures may serve as armor plates. There are three major types of alveolates: ciliates, which move using cilia; dinoflagellates, which use flagella for movement; and apicomplexans, which are...
Colonisation of Pathogens01:25

Colonisation of Pathogens

Pathogen colonization of host tissues is a critical step in the development of infectious diseases. Various pathogenic microorganisms, including bacteria, fungi, viruses, and protozoa, have evolved complex strategies to attach to, invade, and persist within host environments. These mechanisms enable pathogens to establish infections, evade immune responses, and resist antimicrobial treatments.Attachment to Host CellsIn bacteria, colonization typically begins with adherence to host epithelial...
Cryptococcal Meningitis01:27

Cryptococcal Meningitis

Cryptococcal meningitis is a life-threatening opportunistic infection predominantly associated with HIV/AIDS, accounting for over 100,000 deaths annually worldwide. However, it also affects individuals with other forms of immunosuppression, including those undergoing immunosuppressive therapy, organ transplant recipients, patients with innate immunodeficiencies, and individuals with hematological disorders. The infection is caused mainly by Cryptococcus neoformans and Cryptococcus gattii,...
Amebiasis01:28

Amebiasis

Entamoeba histolytica, a protozoan parasite, is responsible for intestinal and extraintestinal amebiasis. Though a significant proportion of infections remain asymptomatic, approximately 50 million individuals annually are estimated to present with clinical disease, resulting in up to 100,000 deaths globally. The disease burden is disproportionately high in regions with lower socioeconomic status, such as parts of India, Africa, Mexico, and Latin America.Etiology and TransmissionThe infective...