Seroprevalence of Pteropine orthoreovirus in humans remain similar after nearly two decades (2001-2002 vs. 2017) in Tioman Island, Malaysia.

Pteropine orthoreovirus (PRV) is an emerging zoonotic respiratory virus that can be transmitted from bats to humans. In Malaysia, aside from PRV2P (Pulau virus) being isolated from Pteropus hypomelanus sampled in Tioman Island, PRV3M (Melaka virus), PRV4K (Kampar virus), and PRV7S (Sikamat virus) were all isolated from samples of patients who reported having a disease spectrum from acute respiratory distress to influenza-like illness and sometimes even with enteric symptoms such as diarrhea and abdominal pain. Screening of sera collected from human volunteers on Tioman Island in 2001-2002 demonstrated that 12.8% (14/109) were positive for PRV2P and PRV3M. Taking all these together, we aim to investigate the serological prevalence of PRV (including PRV4K and PRV7S) among Tioman Island inhabitants again with the assumption that the seroprevalence rate will remain nearly similar to the above reported if human exposure to bats is still happening in the island. Using sera collected from human volunteers on the same island in 2017, we demonstrated seroprevalence of 17.8% (28/157) against PRV2P and PRV3M, respectively. Seropositivity of 11.4% among Tioman Island inhabitants against PRV4K and PRV7S, respectively, was described in this study. In addition, the seroprevalence of 89.5% (17/19), 73.6% (14/19), 63.0% (12/19), and 73.6% (14/19) against PRV2P, PRV3M, PRV4K, and PRV7S, respectively, were observed among pteropid bats in the island. We revealed that the seroprevalence of PRV among island inhabitants remains nearly similar after nearly two decades, suggesting that potential spill-over events in bat-human interface areas in the Tioman Island. We are unclear whether such spillover was directly from bats to humans, as suspected for the PRV3M human cases, or from an intermediate host(s) yet to be identified. There is a high possibility of the viruses circulating among the bats as demonstrated by high seroprevalence against PRV in the bats.

The Role of N-Acetylcysteine Supplementation on the Oxidative Stress Levels, Genotoxicity and Lineage Commitment Potential of Ex Vivo Murine Haematopoietic Stem/Progenitor Cells.

OBJECTIVES: The ex vivo maintenance of haematopoietic stem/progenitor cells (HSPCs) is crucial to ensure a sufficient supply of functional cells for research or therapeutic applications. However, when exposed to reactive oxygen species (ROS) in a normoxic microenvironment, HSPCs exhibit genomic instability which may diminish their quantity and quality. This study aimed to investigate the role of N-acetylcysteine (NAC) supplementation on the oxidative stress levels, genotoxicity and lineage commitment potential of murine haematopoietic stem/progenitor cells (HSPCs). METHODS: This study was carried out at the Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia, between June 2016 and July 2017. Bone marrow cells were isolated from nine mice and cultured in a growth medium. Various concentrations of NAC between 0.125-2 µM were added to the culture for 48 hours; these cells were then compared to non-supplemented cells harvested from the remaining three mice as the control group. A trypan blue exclusion test was performed to determine cell viability, while intracellular ROS levels and genotoxicity were determined by hydroethidine staining and comet assay, respectively. The lineage commitment potential of erythroid, myeloid and pre-B-lymphoid progenitor cells was evaluated via colony-forming cell assay. RESULTS: NAC supplementation at 0.25, 0.5 and 2 µM significantly increased cell viability (P <0.050), while intracellular ROS levels significantly decreased at 0.25 and 0.5 µM (P <0.050). Moreover, DNA damage was significantly reduced at all NAC concentrations (P <0.050). Finally, the potential lineage commitment of the cells was not significantly affected by NAC supplementation (P >0.050). CONCLUSION: The findings of this study indicate that NAC supplementation may potentially overcome the therapeutic limitations of ex vivo-maintained HSPCs.