Pneumocystis carinii: Immunoblotting and immunofluorescent analyses of serum antibodies during experimental rat infection and recovery

Walzer, Peter D.; Stanforth, David A.; Linke, Michael J.; Cushion, Melanie T.

doi:10.1016/0014-4894(87)90179-2

Cited by 50 publications

(29 citation statements)

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“…The rat sera were diluted 1:10 and 1:40 and incubated with a blot containing separated proteins from a standard preparation of P. carinii organisms, as described previously (46,48). Three of the 31 animals received were sacrificed, and lung tissues were harvested and processed for DNA analysis, which was performed by PCR using primers targeted to the large-subunit rRNA of the mitochondrial genome (34).…”

Section: Methodsmentioning

confidence: 99%

Diversity at the Locus Associated with Transcription of a Variable Surface Antigen ofPneumocystis cariniias an Index of Population Structure and Dynamics in Infected Rats

2003

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Pneumocystis carinii expresses a surface glycoprotein called MSG. Different isoforms of MSG are encoded by a gene family spread over at least 15 telomeric sites. Only one locus, called UCS, supports the production of MSG mRNA. Previous studies showed that P. carinii populations from individual rats exhibited high degrees of diversity with respect to the MSG genes attached to the UCS locus. This diversity could have been generated primarily in the rats studied. Alternatively, the rats may have been infected by P. carinii organisms that were already different at the UCS locus. To investigate this issue, we examined the UCS locus in P. carinii from rats that had been exposed to few of the microbes at a specified time, which produced a bottleneck in the microbial population. Some of the rats with bottlenecks produced P. carinii populations in which a single MSG sequence resided at the UCS locus in 80 to 90% of the organisms, showing that P. carinii can proliferate within a rat without generating the very high levels of UCS diversity previously seen. From the degree of diversity observed in the bottlenecked populations, the maximum rate of switching appeared to be 0.01 event per generation. These data also suggest that the infectious dose is as low as one organism, that rats that share a cage readily infect each other, and that the doubling time of P. carinii in vivo is ϳ3 days. In addition, we found that inoculation with 10 7 P. carinii organisms from a population highly heterogeneous at the UCS locus reproduced this heterogeneity. By contrast, shifts in population structure occurred in rats given 10 4 P. carinii organisms, suggesting that a small fraction of these proliferated.Pneumocystis pneumonia is a well-known problem in AIDS patients. Pneumocystis organisms are also found in a variety of nonhuman host species, including nonhuman primates, ferrets, rabbits, horses, shrews, pigs, mice, and rats. Until approximately 1990, a single genus and species name, Pneumocystis carinii, was used in reference to all Pneumocystis organisms regardless of the host species in which they are found. Then, DNA sequence analysis showed that the Pneumocystis organisms found in different host species are quite different from one another and appear to be host species specific. To distinguish these different organisms, a trinomial nomenclature system was adopted (2, 38;

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Section: Methodsmentioning

confidence: 99%

Diversity at the Locus Associated with Transcription of a Variable Surface Antigen ofPneumocystis cariniias an Index of Population Structure and Dynamics in Infected Rats

2003

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“…Rats develop serum antibodies to the 110-to 120-and 45-to 60-kilodalton antigens in a tempo ral pattern which parallels that of the IFA test [22], Data from our laboratory suggest that AIDS patients who develop pneumocys tosis can produce antibodies to individual antigens (particularly the 40-kilodalton band) on Western blots which may not be detectable by the IFA technique. In fact, the loss of antibodies in some of these patients can be correlated with the development of recurrent episodes of P. carinii pneumonia.…”

Section: Antigenic and Surface Characteristicsmentioning

confidence: 74%

Immunobiology of <i>Pneumocystis carinii</i>

Walzer

Cushion²

1989

Path Immunopathol Res

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“…Initially, the study of MSG was via biochemical and immunological approaches, which had significant limitations because P. carinii are difficult to grow, making it difficult to obtain MSG in amounts large enough to allow thorough purification. Despite these difficulties, biochemical studies established that the 120-kDa band contained a glycosylated protein that was on the organism's surface (40,41,65,76,79,80,86,87,101,106,112,117,150,173,177). Material in the 120-kDa band was shown to be recognized by serum antibodies and T cells from exposed hosts (35,36,39,43,45,48,66,76,88,101,111,136,151,152,154), and to bind to several host proteins, including fibronectin, vitronectin, surfactant protein A, and surfactant protein D (34,74,75,93,104,115,116,183 …”

Section: Major Surface Antigen Of P Cariniimentioning

confidence: 99%

Genetics of Surface Antigen Expression inPneumocystis carinii

Stringer

Keely

2001

Infect Immun

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This article reviews the molecular genetic data pertaining to the major surface glycoprotein (MSG) gene family of Pneumocystis carinii and its role in surface variation and compares this fungal system to antigenic variation systems in the protozoan Trypanosoma brucei and the bacteria Borrelia spp. PNEUMOCYSTIS CARINIIPneumocystis carinii is a fungus that can cause pneumonia in immunocompromised mammals (100, 174). While P. carinii was recognized nearly a century ago and has been a significant human pathogen since the beginning of the AIDS epidemic, this organism is not well understood. Much of the blame for the lack of basic information about this organism and its natural history can be placed on its failure to grow well in culture. Populations of the organism can be maintained in broth culture, but growth in culture has not been good enough to allow either production of large numbers or derivation of clonally derived stocks (95). Therefore, in vitro culture has been of limited utility for studying the genetics and biochemistry of P. carinii.By contrast, large numbers of organisms can be routinely obtained from laboratory animals. Most of what is known about P. carinii has been learned from studies with animals, and most of what is known about the surface antigen genes was determined from studies on organisms from laboratory rats. Reliance on rats as the source of P. carinii has had its advantages and disadvantages, which have shaped the course of research on antigenic variation. It is important, therefore, to preface this review with a brief description of the general features of rat models of P. carinii infection.The rat model of P. carinii pneumonia (Pcp) has its roots in studies that showed that P. carinii infections can be provoked by treating rats with chemical immunosuppressants (18,24,38,53). These infections appeared to be caused by growth of P. carinii that was present in the rats at the time of immunosuppression (reactivation of latent infections). Most, if not all, commercial rat colonies harbor P. carinii in a latent form, where it can persist for up to a year (103,162,178). It seems most plausible that P. carinii maintains itself in rat colonies via airborne transmission from older rats to neonates, and evidence for airborne transmission has been obtained in laboratory settings (53,55,176). However, other mechanisms of transmission from adults to neonates have not been excluded, and observations suggestive of transplacental transfer have been reported (17).Even though latent infections are common in laboratory rats, simply immunosuppressing rats does not always lead to the production of large numbers of organisms per animal. This observation led to the implementation of a protocol known as the natural transmission method. In this method, rats are bred in colonies known to harbor latent infections. Young animals in such colonies are immunosuppressed and housed in openair cages. Some or all of the immunosuppressed animals develop heavy infections. When new young animals from another source (such as a...

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Pneumocystis carinii: Immunoblotting and immunofluorescent analyses of serum antibodies during experimental rat infection and recovery

Cited by 50 publications

References 25 publications

Diversity at the Locus Associated with Transcription of a Variable Surface Antigen ofPneumocystis cariniias an Index of Population Structure and Dynamics in Infected Rats

Diversity at the Locus Associated with Transcription of a Variable Surface Antigen ofPneumocystis cariniias an Index of Population Structure and Dynamics in Infected Rats

Immunobiology of <i>Pneumocystis carinii</i>

Genetics of Surface Antigen Expression inPneumocystis carinii

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