Systematics and Evolution, Part A The Mycota

5 Microsporidia

ELIZABETHS. DIDIER^1 ,JAMESJ. BECNEL^2 ,MICHAELL. KENT3,4,JUSTINL. SANDERS^3 ,LOUISM. WEISS^5

CONTENTS

I. Introduction............................... 115

II. Occurrence and Distribution............. 116

A. Arthropod Hosts........................ 116

B. Aquatic Hosts (Marine and

Freshwater) ............................. 119

C. Mammalian and Avian Hosts .......... 120

III. Morphology of the Microsporidian Spore 121

A. General Description and Common

Features ................................. 121

B. Species (Spores) Infecting Arthropod

Hosts.................................... 122

C. Species (Spores) Infecting Aquatic

Hosts.................................... 123

D. Species (Spores) Infecting Mammalian

and Avian Hosts........................ 123

IV. Microsporidian Invasion Apparatus..... 124

V. Life Cycle................................... 126

A. Species Infecting Arthropod Hosts .... 127

B. Species Infecting Aquatic Hosts ....... 128

C. Species Infecting Mammalian and

Avian Hosts ............................. 129

VI. Systematics and Evolution................ 129

VII. Classification............................... 130

VIII. Maintenance and Culture................. 131

A. Species Infecting Arthropod Hosts .... 131

B. Species Infecting Aquatic Hosts ....... 131

C. Species Infecting Mammalian and Avian

Hosts .................................... 132

IX. Conclusions................................ 133

References.................................. 133

I. Introduction

The phylum Microsporidia Balbiani 1882

(Weiser 1977 ) is comprised of a diverse group

of over 1,400 species (Didier and Weiss 2006 ).

These organisms are obligate intracellular path-

ogenic protists uniquely characterized by a

specialized invasion organelle, the polar tube,

through which the cytoplasm and nucleus of

these organisms pass during the infection of

their host cells. Long considered early branch-

ing eukaryotes classified with the Archezoa, the

microsporidia are now considered fungi based

on accumulated data and more sophisticated

analyses (Hibbett et al. 2007 ; James et al.

2006 ).Microsporidia infect commercially sig-

nificant animals, such as honey bees, salmon,

silkworms, farm animals, and companion pets,

and are of medical importance because they

cause emerging opportunistic infections in

humans.A wide range of animals that are less

commercially relevant can also be infected with

microsporidia and thus pose a risk as environ-

mental reservoirs of infection (Santı ́n and Fayer

2009a). As a consequence of studies to better

characterize the tree of life, the microsporidia

have undergone a major transition from place-

ment with the earliest diverging eukaryotes to

(^1) Division of Microbiology, Tulane National Primate Research
Center, 18703 Three Rivers Road, Covington, LA 70433, USA;
e-mail:[email protected]
(^2) USDA, ARS, CMAVE, 1600 S.W. 23rd Drive, Gainesville,
FL 32608, USA; e-mail:[email protected]
(^3) Department of Microbiology, Oregon State University,
220 Nash Hall, Corvallis, OR 97331, USA; e-mail:michael.
[email protected];[email protected]
(^4) Department of Biomedical Sciences, Oregon State University,
Corvallis, OR 97331, USA; e-mail:michael.kent@oregonstate.
edu
(^5) Departments of Medicine and Pathology, Albert Einstein
College of Medicine, 1300 Morris Park Avenue, Room 504
Forchheimer, Bronx, NY 10461, USA; e-mail:louis.weiss@
einstein.yu.edu
Systematics and Evolution, 2ndEdition
The Mycota VII Part A
D.J. McLaughlin and J.W. Spatafora (Eds.)
©Springer-Verlag Berlin Heidelberg 2014