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To determine factors associated with mutations in the Pneumocystis carinii dihydropteroate synthase (DHPS) gene, a prospective study of human immunodeficiency virus (HIV)-infected patients with confirmed P. carinii pneumonia was conducted in Atlanta, Seattle, and San Francisco. Clinical information was obtained from patient interview and chart abstraction. DHPS genotype was determined from DNA sequencing. Overall, 76 (68.5%) of 111 patients had a mutant DHPS genotype, including 22 (81.5%) of 27 patients from San Francisco. In multivariate analysis, sulfa or sulfone prophylaxis and study site were independent predictors of a mutant genotype. Fourteen (53.8%) of 26 patients who were newly diagnosed with HIV infection and had never taken prophylaxis had a mutant genotype. The significance of geographic location as a risk factor for mutant genotype and the high proportion of mutant genotypes among persons never prescribed prophylaxis, including those newly diagnosed with HIV infection, provide indirect evidence that these mutations are transmitted from person to person either directly or through a common environmental source.

International audience; DNA sequence comparison of 412 base-pairs fragments of the mitochondrial cytochrome B gene was used to infer the genetic structure of nine geographical #Triatoma infestans$ populations and their phylogenetic relationship with #T. melanosoma$ and #T. brasiliensis$. #T. infestans$ and #T. melanosoma$ were compared by morphometry, allozyme and cytogenetic analyses, as well as subjected to reciprocal crosses, in order to clarify the taxonomic status of the latter. No differences were found to distinguish the two species and the crosses between them yielded progeny. #T. infestans$ populations presented four haplotypes that could be separated in two clusters : one formed by the samples from Bolivia (Andes and Chaco) and the other formed by samples from Argentina and Brazil. Silvatic and domestic #T. infestans$ populations from Bolivia (Andes) were genetically identical. (Résumé d'auteur)

Kissing bugs or triatomines (Reduviidae: Triatominae) are vectors of the Chagas' disease agent Trypanosoma cruzi. There is a current need for more sensitive tools for use in discrimination of different bug populations and species, thus allowing a better understanding of these insects as it relates to disease transmission and control. In a preliminary analysis of the mitochondrial large subunit ribosomal RNA (mtlsurRNA) and cytochrome B (mtCytB) genes, we used DNA sequencing to study species identification and phylogeny. In both examined gene regions, about 46% of nucleotide positions exhibited polymorphism. The examined region of mtCytB appears to have evolved more rapidly than the examined region of mtlsurRNA. Phylogenetic analysis of both gene fragments in the examined species produced similar results that were generally consistent with the accepted taxonomy of the subfamily. The two major tribes, Rhodniini and Triatomini, were supported, along with additional clades that corresponded to accepted species complexes within the Rhodnius and Triatoma genera. The one chief exception was that Psammolestes coreodes sorted into the Rhodnius prolixus-robustus-neglectus clade, with bootsrap values of 99% and 81%, respectively, for the mtlsurRNA and mtCytB fragments. All of the individual species examined could be distinguished at both genetic loci.

The tsetse thrombin inhibitor, a potent and specific low molecular mass (3,530 Da) anticoagulant peptide, was purified previously from salivary gland extracts of Glossina morsitans morsitans (Diptera: Glossinidae). A 303-bp coding sequence corresponding to the inhibitor has now been isolated from a tsetse salivary gland cDNA library by using degenerate oligonucleotide probes. The full-length cDNA contains a 26-bp untranslated segment at its 5′ end, followed by a 63-bp sequence corresponding to a putative secretory signal peptide. A 96-bp segment codes for the mature tsetse thrombin inhibitor, whose predicted molecular weight matches that of the purified native protein. Based on its lack of homology to any previously described family of molecules, the tsetse thrombin inhibitor appears to represent a unique class of naturally occurring protease inhibitors. Recombinant tsetse thrombin inhibitor expressed in Escherichia coli and the chemically synthesized peptide are both substantially less active than the purified native protein, suggesting that posttranslational modification(s) may be necessary for optimal inhibitory activity. The tsetse thrombin inhibitor gene, which is present as a single copy in the tsetse genome, is expressed at high levels in salivary glands and midguts of adult tsetse flies, suggesting a possible role for the anticoagulant in both feeding and processing of the bloodmeal.

Expression of molecules with antiparasitic activity by genetically transformed symbiotic bacteria of disease-transmitting insects may serve as a powerful approach to control certain arthropod-borne diseases. The endosymbiont of the Chagas disease vector, Rhodnius prolixus , has been transformed to express cecropin A, a peptide lethal to the parasite, Trypanosoma cruzi . In insects carrying the transformed bacteria, cecropin A expression results in elimination or reduction in number of T. cruzi . A method has been devised to spread the transgenic bacteria to populations of R. prolixus , in a manner that mimics their natural coprophagous route of symbiont acquisition.

LAURENCE HUANG, KRISTINA CROTHERS, ALISON MORRIS, GENA GRONER, MELISSA FOX, JOAN R. TURNER, CYNTHIA MERRIFIELD, SHARY EISER, PATRIZIA ZUCCHI and CHARLES B. BEARD Division of Pulmonary and Critical Care Medicine and Positive Health Program, San Francisco General Hospital, University of California San Francisco, San Francisco, CA 94110, and Division of Pulmonary and Critical Care, University of Southern California, Los Angeles, CA, and Division of Parasitic Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA

Five actin genes have been identified in the mosquito Anopheles gambiae, and a constitutively expressed actin gene has been chosen for detailed analysis. We have physically mapped and sequenced this gene and six associated cDNAs, including translated coding regions, as well as the 5' and 3' flanking sequences. Analysis of stage-specific RNA shows this gene to be present in all stages of mosquito development and in an established A. gambiae cell line, thus indicating a cytoskeletal actin. In the sequence of the translated coding region and in pattern of expression, this gene is very similar to the cytoskeletal actin genes of Drosophila melanogaster, and in sequence, equally similar to the Artemia cytoskeletal actin gene 403 (99.2% identity among the three amino acid sequences). Sequencing of this A. gambiae actin gene (designated act1D for its location in chromosome division 1D) and selected cDNAs shows that it possesses three alternative leader sequences; thus the gene appears to have three alternative promoters. These promoters should ultimately prove useful in the production of transgenic constructs for constitutive expression.

Two cDNAs are described from Anopheles gambiae that correspond to the ADP/ATP carrier or translocase. The clones are identical except for minor differences in the 5' non-coding region and in the lengths of the poly-A tails. They code for mRNAs of 1261 and 1263 bp and contain one open reading frame of 906 bp. A probe made from the 1263 bp cDNA hybridized to bands of approximately 1260 and 1700 bp on developmental Northern blots. The putative 300 amino acid peptide sequence shows from 53.4-78.5% identity to AAC peptide sequences from a range of organisms from Zea mays to human. Both clones mapped to region 26a on the left arm of chromosome 2 in An. gambiae.

The spliced leader RNA(SL RNA)-encoding genes of the salivarian New World trypanosome, Trypanosoma rangeli, are organized within the 5S rRNA tandem repeats. Each repeat contains genes encoding an SL RNA and a 5S rRNA in the same orientation of transcription. This SL-5S organization is also present in the African trypanosoma, Trypanosoma vivax. A similar association of SL and 5S genes has been observed in some nematodes, but has not been described previously in trypanosomatids.

A shuttle plasmid was developed that is capable of replicating both in Escherichia coli and in Rhodococcus rhodnii, a bacterial symbiont of the Chagas' disease vector Rhodnius prolixus. We have been able to transform R. rhodnii with this plasmid, infect aposymbiotic R. prolixus with the transformed symbionts, select with the antibiotic thiostrepton, and re-isolate genetically altered symbionts from the insects following successive molts. Symbiotic bacteria are potentially valuable as vehicles for the stable introduction of foreign genes into insects with the goal of eventually altering the ability of the insect to transmit a pathogenic agent.

To the Editor: Our 2002 article in Emerging Infectious Diseases about nomenclature changes for organisms in the genus Pneumocystis (1) has been widely cited and probably will remain a source for persons seeking information about this subject. Therefore, we need to correct an error in 1 of the species names presented in our article and in the 1999 article by Frenkel (2) on which our article was based. In the 1999 article, Frenkel proposed that the species of Pneumocystis found in humans be named to honor the Czech parasitologist, Otto Jirovec. The 1999 article was his second proposal for this change. In 1976, he first named the human pathogen Pneumocystis jiroveci (3), at which time it was classified as a protozoan and therefore named according to the International Code of Zoological Nomenclature. By 1999, it had become clear that the organisms in the genus Pneumocystis are fungi, which are named according to the International Code of Botanical Nomenclature (ICBN) (4). Differences between the International Code of Zoological Nomenclature and ICBN resulted in the realization of an error in the species epithet proposed by Frenkel in 1999, and our 2002 article contained this error. Frenkel’s 1999 article should have modified the species epithet from “jiroveci” to “jirovecii,” (ICBN Articles 32.7 and 60.11 and Rec. 60C.1b). The correct and valid name under ICBN is Pneumocystis jirovecii. Redhead et al. further explain the basis for this correction (5).

A new species of microsporidium, Nolleria pulicis, is described and named here from the cat flea, Ctenocephalides felis. The genus Nolleria is created and placed within the family Chytridiopsidae. The family is slightly modified to accommodate certain features of intracellular development seen in N. pulicis, which is otherwise very similar to other species in the family Chytridiopsidae. Sporulation is described from ultrastructural analysis of infected midgut epithelial cells of adult C. felis. The term "multiple division by vacuolation" is proposed for describing sporogony as it occurs in this species and certain related species of microsporidia. The probable mode of transmission and apparent absence of merogony are discussed.

This note describes the ultrastructure and cytopathology of what appears to be a nonoccluded baculovirus. This apparent nonoccluded baculovirus, reported here from specimens of P. simulans, is the first record of a baculovirus in the order Siphonaptera

Susceptibility levels of domestic and peridomestic strains of Aedes aegypti in New Orleans, Louisiana, USA, to malathion, DDT, permethrin, and resmethrin were studied. Larval assays were performed according to the standard WHO method for determining insecticide susceptibility or resistance. All 4 of the field strains assayed were found to be highly susceptible to malathion and resmethrin but highly resistant to DDT. A slight reduction in susceptibility to permethrin was found. Resistance to DDT was lower in a tree-hole strain than in the domestic strains, suggesting a domestic source of resistance. While DDT resistance is not an uncommon phenomenon today, it was not expected in New Orleans, since DDT has not been used there for the control of Ae. aegypti for over 20 years; moreover, at the time DDT was last being used for control, the local population of Ae. aegypti was susceptible to this chemcial.

An adult female Triatoma sanguisuga was found to be naturally infected with Trypanosoma cruzi. This is the first report of a T. cruzi infection in this bug in Florida and suggests that a study of trypanosomiasis in reservoirs and vectors in north Florida is warranted.

Une nouvelle espece de Leptomonas est isolee et decrite chez la puce P.s. La structure, l'ultrastructure, l'influence de la temperature sur la croissance, la transmission et la specificite de l'hote sont etudiees