Systemic spironucleosis in 2 immunodeficient rhesus macaques (Macaca mulatta)

Abstract

Spironucleus spp are parasites of fish and terrestrial vertebrates, including mice and turkeys, that rarely cause extraintestinal disease. Two rhesus macaques (Macaca mulatta) were experimentally inoculated with simian immunodeficiency virus mac251. Both progressed to simian acquired immune deficiency syndrome within 1 year of inoculation and developed systemic protozoal infections in addition to common opportunistic infections, including rhesus cytomegalovirus, rhesus lymphocryptovirus, and rhesus adenovirus. In the first case, the protozoa were associated with colitis, multifocal abdominal abscessation, and lymphadenitis. In the second case, they were one of a number of organisms associated with extensive pyogranulomatous pneumonia and colitis. Ultrastructural, molecular, and phylogenetic analysis revealed the causative organism to be a species of Spironucleus closely related to Spironucleus meleagridis of turkeys. This report is the first of extraintestinal infection with Spironucleus sp in higher mammals and expands the list of opportunistic infections found in immunocompromised rhesus macaques.

Fig. 1

Abscess; Animal No. 1. Organisms contain apically oriented and closely associated nuclei (arrowheads). Two cytopharynxes, visible as negatively staining lines, transverse the cell posteriorly (arrows). The flagella do not stain. Wright’s stain.

Fig. 2

Lymph node; Animal No. 1. The lymph node is partially effaced by an incipient pyogranuloma. HE.

Fig. 3

Lymph node; Animal No. 1. Numerous protozoa (arrows) are interspersed among the inflammatory cells. HE.

Fig. 4

Lung; Animal No. 2. Extensive regions of lung are obliterated by an inflammatory infiltrate of neutrophils and macrophages. HE.

Fig. 5

Lung; Animal No. 2. Numerous protozoa (arrows) partially fill the alveoli at the periphery of the inflammatory infiltrate. HE.

Fig. 6

Electron micrograph; Animal No. 1. A partially degenerate protozoan has been engulfed by a macrophage. Parallel flagella are visible in cross section lined up along the cell membrane (arrowheads). Bar = 1μm.

Fig. 7

Electron micrograph; Animal No. 2. In longitudinal section, the two nuclei are closely apposed and arranged in an “S”-shaped configuration (arrows). The origins of the recurrent flagella are indicated by arrowheads. Electron dense glycogen granules congregate around the base of one flagellum. Bar = 1μm.

Fig. 8

Electron micrograph; Animal No. 1. An organism is captured in cross section such that the nuclei appear in plane of section three times (arrows). Recurrent flagella are indicated by arrowheads. This organism is being engulfed by a neutrophil (top) and the membrane is focally degraded (double arrow). Bar = 1μm.

Fig. 9

A phylogenetic tree clusters the unknown with Spironucleus meleagridis.

Fig. 10

Results of PCR on fecal samples using broad based HTTS2 primers. Lanes 1–10, uninfected animals. Lanes 11–20, SIV-infected animals. +, positive control DNA from case No. 1. −, no template control. Products of the expected 310bp size were obtained from all fecal samples.

Fig. 11

Nested PCR reactions using 1μl of template from each of the HTTS2 products depicted in Fig. 10. Lanes 1–10, uninfected animals. Lanes 11–20, SIV-infected animals. +, positive control DNA from case No. 1. −, no template control. Products of the expected 150bp size were obtained from six of the uninfected and nine of the infected animals.