| Summary: | <p>Abstract</p> <p>Background</p> <p><it>Brugia malayi </it>and <it>B. pahangi </it>are two closely related nematodes that cause filariasis in humans and animals. However, <it>B. pahangi </it>microfilariae are able to develop in and be transmitted by the mosquito, <it>Armigeres subalbatus</it>, whereas most <it>B. malayi </it>are rapidly melanized and destroyed within the mosquito hemocoel. A cross-species microarray analysis employing the <it>B. malayi </it>V2 array was carried out to determine the transcriptional differences between <it>B. malayi </it>and <it>B. pahangi </it>microfilariae with similar age distribution.</p> <p>Results</p> <p>Following microarray data analysis, a list of preferentially expressed genes in both microfilariae species was generated with a false discovery rate estimate of 5% and a signal intensity ratio of 2 or higher in either species. A total of 308 probes were preferentially expressed in both species with 149 probes, representing 123 genes, in <it>B. pahangi </it>microfilariae and 159 probes, representing 107 genes, in <it>B. malayi </it>microfilariae. In <it>B. pahangi</it>, there were 76 (62%) up-regulated transcripts that coded for known proteins that mapped into the KEGG pathway compared to 61 (57%) transcripts in <it>B. malayi </it>microfilariae. The remaining 47 (38%) transcripts in <it>B. pahangi </it>and 46 (43%) transcripts in <it>B. malayi </it>microfilariae were comprised almost entirely of hypothetical genes of unknown function. Twenty-seven of the transcripts in <it>B. pahangi </it>microfilariae coded for proteins that associate with the secretory pathway compared to thirty-nine in <it>B. malayi </it>microfilariae. The data obtained from real-time PCR analysis of ten genes selected from the microarray list of preferentially expressed genes showed good concordance with the microarray data, indicating that the microarray data were reproducible.</p> <p>Conclusion</p> <p>In this study, we identified gene transcripts that were preferentially expressed in the microfilariae of <it>B. pahangi </it>and <it>B. malayi</it>, some of which coded for known immunomodulatory proteins. These comparative transcriptome data will be of interest to researchers keen on understanding the inherent differences, at the molecular level, between <it>B. malayi </it>and <it>B. pahangi </it>microfilariae especially because these microfilariae are capable of surviving in the same vertebrate host but elicit different immune response outcomes in the mosquito, <it>Ar. subalbatus</it>.</p>
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