Characterizing Pneumocystis in the lungs of bats: understanding Pneumocystis evolution and the spread of Pneumocystis organisms in mammal populations

Abstract

Bats belong to a wide variety of species and occupy diversified habitats, from cities to the countryside. Their different diets (i.e., nectarivore, frugivore, insectivore, hematophage) lead Chiroptera to colonize a range of ecological niches. These flying mammals exert an undisputable impact on both ecosystems and circulation of pathogens that they harbor. Pneumocystis species are recognized as major opportunistic fungal pathogens which cause life-threatening pneumonia in severely immunocompromised or weakened mammals. Pneumocystis consists of a heterogeneous group of highly adapted host-specific fungal parasites that colonize a wide range of mammalian hosts. In the present study, 216 lungs of 19 bat species, sampled from diverse biotopes in the New and Old Worlds, were examined. Each bat species may be harboring a specific Pneumocystis species. We report 32.9% of Pneumocystis carriage in wild bats (41.9% in Microchiroptera). Ecological and behavioral factors (elevation, crowding, migration) seemed to influence the Pneumocystis carriage. This study suggests that Pneumocystis-host association may yield much information on Pneumocystis transmission, phylogeny, and biology in mammals. Moreover, the link between genetic variability of Pneumocystis isolated from populations of the same bat species and their geographic area could be exploited in terms of phylogeography.

Fig 1

Genetic polymorphism of Pneumocystis isolates detected in the lungs of Tadarida brasiliensis bats sampled from North and South America. For each geographic location, mtLSU rDNA and mtSSU rDNA Pneumocystis polymorphic sequences are indicated and framed: two mtLSU rDNA variants and three mtSSU rDNA variants. The number of positive samples over total number of analyzed samples is also indicated below each location. The photo represents one male bat belonging to the species Tadarida brasiliensis and originating from Dique Escaba in Argentina.

Fig 2

Phenetic relationships of Pneumocystis organisms from bat species inferred from mtLSU rDNA sequences. The phylogram presented resulted from bootstrapped data sets obtained by using BIONJ analysis (heuristic search option in PAUP 4.0). The percentages above the branches are the frequencies with which a given branch appeared in 1,000 bootstrap replications. Bootstrap values below 50% are not displayed. Branch lengths correspond to the total nucleotide changes assigned to each branch by PAUP 4.0. Pneumocystis from rabbit (P. oryctolagi, GenBank accession S42915) and from mouse (P. murina, GenBank accession AF257179) were chosen as outgroups. Letter and number codes indicate geographic origin and reference number of samples, respectively. M, Michoacán, Mexico; A, Argentina; JG, Juxtlahuaca Grotto, Mexico; OW, Old World; NW, New World. Letters and numbers in parentheses indicate a particular sample (P6, 13, 34).

Fig 3

Phenetic relationships of Pneumocystis organisms from bat species inferred from mtSSU rDNA sequences. The phylogram presented resulted from bootstrapped data sets obtained by using BIONJ analysis (heuristic search option in PAUP 4.0). The percentages above the branches are the frequencies with which a given branch appeared in 1,000 bootstrap replications. Bootstrap values below 50% are not displayed. Branch lengths correspond to the total nucleotide changes assigned to each branch by PAUP 4.0. Pneumocystis from rabbit (P. oryctolagi [47]) and from hare (P. f. sp. Lepus europaeus, GenBank accession JF431106) were chosen as outgroups. Letter and number codes indicate geographic origin and reference number of samples, respectively. NL, Nuevo León, Mexico; M, Michoacán, Mexico; A, Argentina; OW, Old World; NW, New World. Letters and numbers in parentheses indicate a particular sample (P3, P6, 12, 26).