Population structure of rat-derived Pneumocystis carinii in Danish wild rats

Palmer, RJ Settnes, OP Lodal, J Wakefield, AE

Rj. Palmer et al., Population structure of rat-derived Pneumocystis carinii in Danish wild rats, APPL ENVIR, 66(11), 2000, pp. 4954

61

INGLESE

Article

Biology,Microbiology

APPLIED AND ENVIRONMENTAL MICROBIOLOGY

0099-2240 → ACNP

66

11

2000

ISI

0099-2240(200011)66:11<4954:PSORPC>2.0.ZU;2-S

The rat model of Pneumocystis carinii pneumonia is frequently used to study human P. carinii infection, but there are many differences between the rat and human infections. We studied naturally acquired P. carinii in wild rat s to examine the relevance of the rat model for human infection. P. carinii DNA was detected in 47 of 51 wild rats and in 10 of 12 nonimmunosuppressed laboratory rats. Evidence for three novel formae speciales of rat-derived P. carinii was found, and these were provisionally named Pneumocystis carin ii f. sp. rattus-secundi, Pneumocystis carinii f. sp. rattus-tertii, and Pn eumocystis carinii f. sp. rattus-quarti. Our data suggest that low-level ca rriage of P. carinii in wild rats and nonimmunosuppressed laboratory rats i s common and that wild rats are frequently coinfected with more than one fo rma specialis of P. carinii. We also examined the diversity in the internal ly transcribed spacer (ITS) regions of the nuclear rRNA operon of Pneumocys tis carini f. sp. carinii by using samples from wild rats and laboratory ra ts and spore trap samples. We report a lack of variation in the ITS1 and IT S2 regions that is consistent with an evolutionary bottleneck in the P. car inii f. sp. carinii population. This study shows that human- and rat-derive d P. carinii organisms are very different, not only in genetic composition but also in population structure and natural history.