Biology subjects

Narpon, Q.

Publications and source records attributed to Narpon, Q..

3 recordsLinked to original sources

bioRxiv2026

Understanding malaria transmission in Angola: first detection of Plasmodium malariae in Anopheles spp. and the role of secondary vectors in the Balombo region, Benguela Province

Background: Angola is one of the most affected countries in sub-Saharan Africa and was off-track to meet the WHO Global Technical Strategy targeting of a 75% reduction in malaria incidence and mortality by 2025. Recent studies highlighted major knowledge gaps regarding malaria vectors in Angola, particularly secondary vectors. A malaria control project initiated in 2007 in Balombo (Benguela Province, central Angola) has monitored malaria dynamics for 18 years, revealing increased Plasmodium prevalence and more frequent detection of non-falciparum species, mainly Plasmodium malariae (in co-infection with P. falciparum) in villagers of the Balombo region. This study aimed to characterize Anopheles populations in this region by assessing species composition, behavioural patterns, and infection rate. And to a less extent, to compare the performance of two indoor and outdoor mosquito trapping methods. Methods: Surveys were conducted during the rainy (December 2023 and 2024) and dry seasons (July 2024) in villages around the town of Balombo. Adult mosquitoes were collected indoors and outdoors using CDC Light Traps and BG-Pro traps in randomly selected houses. Female Anopheles were morphologically and molecularly identified. Primary and secondary vectors were screened for Plasmodium spp. using qPCR-high resolution melting, and positive samples were sequenced. Results: A strong seasonal effect was observed in Anopheles populations, with higher abundance, diversity, and Plasmodium- infection rates during the rainy season. An. funestus remained the main vector, but Plasmodium spp. was also detected in five other species: An. arabiensis, An. gambiae, An. marshallii, An. rufipes, and An. maculipalpis. This is the first report of P. malariae in Anopheles mosquitoes and the first mention of the role of secondary vectors in malaria transmission in Benguela Province. Conclusion: This study provides a thorough and updated inventory of Anopheles species in the Balombo region. Molecular biology confirmed the presence of P. falciparum and P. malariae in several species of Anopheles underscoring the existence of a complex transmission system in villages of Balombo. Infected exophagic and exophilic Anopheles species, exhibiting opportunistic behaviour, likely contribute, as secondary vectors, to the increase of Plasmodiumspp. transmission in the study sites. Therefore, confirming the need to implement complementary interventions targeting outdoor malaria transmission.

microbiology↗

bioRxiv2025

Multiple orthoflaviviruses secrete sfRNA in mosquito saliva to promote transmission by inhibiting MDA5-mediated early interferon response

Numerous orthoflaviviruses transmitted through the bites of different mosquito species infect more than 500 million people annually. Skin infection at the bite site represents a critical and conserved step in transmission and a deeper understanding of this process will promote the design of broad-spectrum interventions to address diverse orthoflavivirus health threats. Here, we identify and characterize a transmission-enhancing viral factor in mosquito saliva that is shared across orthoflaviviruses. Saliva from West Nile virus-infected Culex and Zika virus-infected Aedes contains a viral non-coding RNA, subgenomic flaviviral RNA (sfRNA), within lipid vesicles distinct from virions. Higher concentration of sfRNA in infectious saliva positively correlates with infection intensity in human cells and skin explants. Early sfRNA delivery into transmission-relevant skin cell types and human skin explant demonstrate that sfRNA is responsible for the infection enhancement. Co-inoculation of sfRNA in a mouse model of transmission enhanced skin infection and worsened disease severity, supporting the role of salivary sfRNA as a transmission-enhancer. Mechanistically, salivary sfRNA attenuates early interferon response in human skin cells and skin explants by disrupting MDA5 signaling. Our results, derived from two distinct orthoflaviviruses and supported by prior studies, establish salivary sfRNA as a pan-orthoflavivirus transmission-enhancing factor driven by a conserved viral non-coding RNA.

immunology↗

bioRxiv2024

West Nile virus is transmitted within mosquito populations through infectious mosquito excreta

Understanding transmission routes of arboviruses is key to control their epidemiology and global health burden. Using West Nile virus and Culex mosquitoes, we tested whether arboviruses are transmitted through mosquito excreta. First, we determined the presence of infectious virions in excreta and quantified a high concentration of infectious units per excreta. Second, we showed that virion excretion starts early after oral infection and remains constant for a long period, regardless of mosquito infection level. These results highlight the infectiousness of excreta from infected mosquitoes. Third, we found that both larvae and pupae were susceptible to infection, although pupae were highly permissive. Forth, we established the proof-of-concept that immature mosqui-toes can be infected by infectious excreta, demonstrating a new excreta-mediated mode of transmission. Finally, by mathematically modelling excreta-mediated transmission in the field, we demonstrated its potential impact on arbovirus epidemiology. Our study uncovers a new route of transmission for arboviruses, unveiling mechanisms of viral maintenance in mosquito reservoirs and of vector species shift that contribute to zoonotic emergence.

zoology↗