Biology subjects

Fischer, P. U.

Publications and source records attributed to Fischer, P. U..

4 recordsLinked to original sources

bioRxiv2026

Detection of Plasmodium infections in macaques from areas endemic for brugian filariasis in Belitung District, Indonesia

Background Malaria caused by Plasmodium knowlesi and lymphatic filariasis caused by Brugia malayi are mosquito-borne infections with non-human primates as reservoirs. P. knowlesi has emerged as a significant cause of human malaria in Southeast Asia over the past two decades. Belitung district, Indonesia, was until recently assumed to have eliminated B. malayi until infections were detected in humans and long-tailed macaques. To investigate whether the local reservoir of B. malayi is also a reservoir for malaria we screened macaques from 4 areas in Belitung for malaria parasites. Methods and findings Blood samples from 163 long-tailed macaques (Macaca fascicularis) that had been tested for B. malayi were examined by quantitative PCR assays specific for Plasmodium spp., P. knowlesi, P. inui, P. coatneyi and P. cynomolgi. A total of 130 macaques (79.8%) tested positive in the pan-Plasmodium qPCR assay. Plasmodium inui was most prevalent (41.7%), followed by P. knowlesi (38.7%), P. coatneyi (24.5%) and P. cynomolgi (13.5%). Multiple species infections, with 2-3 Plasmodium species were detected in 37% of macaques. Notably, 20 (91%) of 22 B. malayi-positive macaques were co-infected with at least one Plasmodium species. We sequenced the complete mitochondrion from 9 samples diagnosed by qPCR as mono-infections. Phylogenetic analysis confirmed 7 as P. knowlesi, and the other two as P. inui and P. coatneyi. Phylogenetic and pairwise analysis revealed that P. knowlesi isolates from Belitung were closely related to each other and to P. knowlesi from humans and monkeys from Thailand, Malaysia and Indonesia. Conclusions Molecular evidence shows high prevalence of zoonotic malaria parasites in macaques from Belitung, emphasizing the risk of human transmission. Increased surveillance, improved diagnostics, and targeted interventions are needed to prevent zoonotic spillover of P. knowlesi as it has been observed for B. malayi in Belitung.

microbiology↗

bioRxiv2026

Mitochondrial genomes of individual microfilariae: Undescribed Dirofilaria-like filariae from Malaysian cats and two filaria species related to Dirofilaria and Mansonella from Indonesian macaques

Three molecularly undescribed filarial species were co-detected, while screening animals for Brugia malayi, the agent of lymphatic filariasis. Single microfilariae (Mf) isolated from blood samples of crab-eating macaques (Macaca fascicularis) from Belitung, Indonesia, and from pet dogs and cats in Sabah, Malaysia, were analyzed. Among 163 macaques, 33 (20.2%) were positive for large Mf (mean length 498.9 {micro}m) similar to Dirofilaria ( Belitung I). One macaque was infected with small Mf (mean length 150.4 {micro}m) ( Belitung II), with a high density of 17,150 Mf/mL. In two cats co-infected with B. malayi, Mf of a Dirofilaria species ( Sabah) with an average length of 299.1 {micro}m were detected. Morphometric analysis of Mf showed distinct differences between these three species and other Mf described in the area. Whole genome amplification and genome sequencing of 24 individual Mf enabled phylogenetic analysis of mitochondrial genomes, and analysis of specific mitochondrial and nuclear barcode regions. The three Mf groups formed distinct clusters and did not match any currently available reference sequence. Cluster Belitung I from macaques formed a sister group to all other Dirofilaria. Cluster Belitung II included bird filariae and primate filariae of the genus Mansonella as close relatives. The cluster Sabah formed a monophyletic group with the zoonotic species D. asiatica and Dirofilaria sp. Thailand. DNA of Wolbachia endobacteria was detected in Mf of Belitung I and Sabah, but not in Belitung II. These findings highlight the limited understanding of filarial diversity in macaques and cats in Asia and underscore the need for a more comprehensive approach that combines morphological and molecular data to identify and assess the pathogenicity and zoonotic potential of these parasites. Author summaryFilarial worms are parasitic nematodes that infect humans and animals and are often transmitted by the same vector mosquito. We identified three molecularly undescribed filarial species while investigating animals as reservoirs for the agent of lymphatic filariasis, Brugia malayi on Belitung Island, Indonesia, and in Sabah, Malaysia. Blood samples were collected from Indonesian macaques and Malaysian pet cats. Out of 163 macaques, 20.2% tested positive for exceptionally large microfilariae (Mf) of an unclassified Dirofilaria-like species (Belitung I). Another filarial species ( Belitung II) with very small Mf, but with a remarkably high density of 17,150 Mf/mL was detected in one macaque. Two cats harbored medium sized Mf of a Dirofilaria species (Sabah). Genetic analysis revealed unique phylogenetic clusters that did not match any reference sequence. Dirofilaria sp. Sabah was closely related to the zoonotic D. asiatica complex, whereas Belitung I clustered as a sister group to Dirofilaria. Belitung II Mf clustered next to but not within the Mansonella spp. cluster. DNA of Wolbachia endobacteria was only detected in Mf of Belitung I and Sabah. These findings highlight the limited understanding of filarial diversity in animals and underscore the need for a comprehensive approach that combines morphological and molecular data to identify and assess the pathogenicity and zoonotic potential of these parasites.

microbiology↗

bioRxiv2024

Spatial proteomics of Onchocerca volvulus with pleomorphic neoplasms shows local and systemic dysregulation of protein expression

Onchocerca volvulus is the agent of onchocerciasis (river blindness) and targeted by WHO for elimination though mass drug administration with ivermectin. A small percentage of adult worms develop pleomorphic neoplasms (PN) that are positively associated with the frequency of ivermectin treatment. Worms with PN have a lower life expectancy and a better understanding about the proteins expressed in PN, and how PN affect protein expression in different tissues could help to elucidate the mechanisms of macrofilaricidal activity of ivermectin. Within a clinical trial of drug combinations that included ivermectin, we detected 24 (5.6%) O. volvulus females with PN by histology of paraffin embedded nodules. To assess the protein inventory of the neoplasms and to identify proteins that may be associated with tumor development, we used laser capture microdissection and highly sensitive mass spectrometry analysis. Neoplasm tissue from three female worms was analyzed, and compared to normal tissues from the body wall, uterus and intestine from the same worms, and to tissues from three females without PN. The healthy females showed all intact embryogenesis. In PN worms, 151 proteins were detected in the body wall, 215 proteins in the intestine, 47 proteins in the uterus and 1,577 proteins in the neoplasms. Only the uterus of one PN female with some stretched intrauterine microfilariae had an elevated number of proteins (601) detectable, while in the uteri of the healthy females 1,710 proteins were detected. Even in tissues that were not directly affected by PN (intestine, body wall), fewer proteins were detected compared to the corresponding tissue of the healthy controls. Immunolocalization of the calcium binding protein OvDig-1 (OVOC8391) confirmed the detection in PN by mass spectrometry. In conclusion we identified proteins that are potentially linked to the development of PN, and systemic dysregulation of protein expression may contribute to worm mortality. Author summaryOnchocerca volvulus, the causative agent of onchocerciasis (river blindness), is targeted for elimination by WHO. The primary strategy involves mass administration of ivermectin. A small proportion of adult female worms develop pleomorphic neoplasms (PN). Here, we used laser capture microdissection and highly sensitive mass spectrometry analysis to determine the protein inventory of PN to identify proteins that may be associated with tumor development. Neoplasm tissue from female worms was analyzed, and compared to normal tissue from the body wall, uterus and intestine from the same worms, and to tissues from females without PN. When compared, PN and healthy control (HC) worms display a different set of proteins, the PN tissue being the one with the highest number of proteins (1,390). From these, 594 were not present in any HC worm tissue. Despite the large number of proteins identified in PN tissue, their low abundance suggests also in PN dysregulation of protein expression. Immunolocalization of a calcium binding protein detected in PN confirmed the mass spectrometry results. In conclusion, we have developed a system to analyze the proteome of O. volvulus from nodule sections and identified proteins that are potentially linked to the development of PN and may contribute to worm mortality.

molecular biology↗

bioRxiv2021

Isolation and characterization of a novel Wolbachia bacteriophage from Allonemobius socius crickets in Missouri

Wolbachia are endosymbionts of numerous arthropod and some nematode species, are important for their development and if present can cause distinct phenotypes of their hosts. Prophage DNA has been frequently detected in Wolbachia, but particles of Wolbachia bacteriophages (phage WO) have been only occasionally isolated. Here, we report the characterization and isolation of a phage WO of the southern ground cricket, Allonemobius socius, and provided the first whole-genome sequence of phage WO from this arthropod family outside of Asia. We screened A. socius abdomen DNA extracts from a cricket population in eastern Missouri by quantitative PCR for Wolbachia surface protein and phage WO capsid protein and found a prevalence of 55% and 50%, respectively, with many crickets positive for both. Immunohistochemistry using antibodies against Wolbachia surface protein showed many Wolbachia clusters in the reproductive system of female crickets. Whole-genome sequencing using Oxford Nanopore MinION and Illumina technology allowed for the assembly of a high-quality, 55 kb phage genome containing 63 open reading frames (ORF) encoding for phage WO structural proteins and host lysis and transcriptional manipulation. Taxonomically important regions of the assembled phage genome were validated by Sanger sequencing of PCR amplicons. Analysis of the nucleotides sequences of the ORFs encoding the large terminase subunit (ORF2) and minor capsid (ORF7) frequently used for phage WO phylogenetics showed highest homology to phage WOKue of the Mediterranean flour moth Ephestia kuehniella (94.18% identity) and WOLig of the coronet moth, Craniophora ligustri (96.86% identity), respectively. Transmission electron microscopy examination of cricket ovaries showed a high density of phage particles within Wolbachia cells. Isolation of phage WO revealed particles characterized by 40-62 nm diameter heads and up to 190 nm long tails. This study provides the first detailed description and genomic characterization of phage WO from North America that is easily accessible in a widely distributed cricket species.

microbiology↗