Molecular Epidemiology of Mansonella Species in Gabon

Abstract

Mansonella perstans, a filarial nematode, infects large populations in Africa and Latin America. Recently, a potential new species Mansonella sp. “DEUX” was reported. Carriage of endosymbiotic Wolbachia opens treatment options for Mansonella infections. Within a cross-sectional study, we assessed the prevalence of filarial infections in 834 Gabonese individuals and the presence of the endosymbiont Wolbachia. Almost half of the participants (400/834, 48%) were infected with filarial nematodes, with Mansonella sp. “DEUX” being the most frequent (295/400, 74%), followed by Loa loa (273/400, 68%), and M. perstans (82/400, 21%). Being adult/elderly, male, and living in rural areas was associated with a higher risk of infection. Wolbachia carriage was confirmed in M. perstans and Mansonella sp. “DEUX”. In silico analysis revealed that Mansonella sp. “DEUX” is not detected with currently published M. perstans specific assays. Mansonella infections are highly prevalent in Gabon and might have been underreported, likely also beyond Gabon.

Multiple origins of nematode-Wolbachiasymbiosis in supergroup F and convergent loss of bacterioferritin in filarialWolbachia

“…These observations indicate that even within a locality, Wolbachia levels can vary between different isolates, and could be a possible explanation for conflicting reports on the presence and absence of Wolbachia in M. perstans 25–27, 31–33 . In addition to potential natural variation, previous exposure to antibiotics can also be a cause of very low Wolbachia levels, and could be another explanation for the occasional failures to detect Wolbachia in PCR-based assays 25–27, 31–33 .…”

“…For the other M. perstans sample Mpe2 obtained from the same geographical location as Mpe1, only 12 small contigs corresponding to Wolbachia were found at very low coverage, demonstrating that the endosymbiont was present at extremely low levels, precluding accurate titer estimation. These observations indicate that even within a locality, Wolbachia levels can vary between different isolates, and could be a possible explanation for conflicting reports on the presence and absence of Wolbachia in M. perstans [25][26][27][31][32][33] . In addition to potential natural variation, previous exposure to antibiotics can also be a cause of very low Wolbachia levels, and could be another explanation for the occasional failures to detect Wolbachia in PCR-based assays [25][26][27][31][32][33] .…”

“…Assuming 1000 nematode cells per microfilaria 59 indicating that the lack of Wolbachia contigs is not due to insufficient depth of coverage and is rather most likely due to a very low titer of Wolbachia in this sample. Since both isolates were collected in Cameroon, these observations point to variation in Wolbachia titers within the same species in a geographical area and could explain the conflicting reports on detection of Wolbachia in M. perstans [25][26][27][31][32][33] .…”

“…perstans was performed and provided some insights into the longstanding controversy around the status of Wolbachia across different Mansonella perstans isolates [25][26][27][31][32][33] . Additionally, comparative analyses between wMoz and wMpe, as well as across other filarial and arthropod Wolbachia genomes are also performed and reported.…”

“…The genome drafts are of high quality based on assessment of completeness using presence of conserved Wolbachia core genes as a metric. Analysis of deep-sequencing data from additional isolates of M. ozzardi and M. perstans was performed and provided some insights into the longstanding controversy around the status of Wolbachia across different Mansonella perstans isolates 25–27, 31–33 . Additionally, comparative analyses between w Moz and w Mpe, as well as across other filarial and arthropod Wolbachia genomes are also performed and reported.…”