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Abstract The COVID-19 pandemic has caused a large number of diseases worldwide. There are few vaccines to constrain this disease and the value of them is high. In this sense, the antigens of the vaccine platform Soberana, the receptor binding domain from SARS-CoV-2 Spike protein, both the monomeric (mRBD) and dimeric (dRBD) forms, have been developed. This study encompassed several analyses by different techniques like circular dichroism (CD), fluorescence spectroscopy (FS) and Gel Filtration- High Performance Liquid ChLC of mRBD and dRBD. Monomer and dimer exhibited similar far-UV CD spectral characteristics with 54% of β-sheet content. Similar conformational features according to near-UV CD and FS studies were observed in both RBD. Stress stability studies by far-UV CD, FS, biological activity and GF-HPLC at 37 °C showed that mRBD is very stable. On the other hand, dRBD fluorescent emission showed a shift towards higher wavelengths as the incubation time increases, suggesting exposition of tryptophan residues, unlike what happens with mRBD. Biological activity outcome confirms these results. GF-HPLC profiles showed that in mRBD, the product of molecular stress are dimers and does not increase over time. However, dRBD showed dimer fragmentation as the main degradation species. This study reveals the usefulness of CD techniques for the analysis of degradation of RBD molecules as well as showed the difference in stability of both RBD molecules. Besides, our work provides useful insights into the production of a key protein used in diagnosis and therapeutics to fight COVID-19 pandemia.

Abstract Background Methadone maintenance treatment (MMT) improves patients’ ability to access HIV-related services and reduces needle sharing and other risky HIV-related behaviors. However, patients may continue to engage in risky sexual practices. In this study, we evaluate sexual behaviors of MMT patients in a mountainous province in Northern Vietnam. Methods We explored the health status, MMT and substance use history, and sexual practices of 241 male MMT patients in Tuyen Quang province. Health status was investigated using the EuroQOL-5 Dimensions-5 Levels (EQ-5D-5 L). Multivariate logistic regression was employed to assess associated factors. Results Most patients (66.4%) reported having at least one sexual partner within the previous twelve months. Most of these partners were spouses or primary partners (72.6%). About 8.3% of patients had casual partners, and 5.8% had visited sex workers; of those who engaged in casual sexual relationships, 90.9% reported using condoms. Current drug use and living in a remote area were associated with an increased odd of having two or more sexual partners, while anxiety or depression was associated with lower odds. Conclusion This study highlights a low proportion of having sexual risk behaviors among MMT patients in Vietnamese mountainous settings. Integrating education about safe sexual practices into MMT services, along with providing medical care and ensuring methadone treatment adherence, is an important component in HIV risk reduction for these patients who were at risk of unsafe sexual practices.

Abstract Background Methadone maintenance treatment (MMT) patients face unique costs associated with their healthcare expenditures. As such, it is important that these patients have access to health insurance (HI) to help them pay for both routine and unforeseen health services. In this study, we explored factors related to health insurance enrollment and utilization among MMT patients, to move Vietnam closer to universal coverage among this patient population. Methods A cross-sectional study was conducted with 1003 patients enrolled in MMT in five clinics in Hanoi and Nam Dinh provinces. Patients were asked a range of questions about their health, health expenditures, and health insurance access and utilization. We used multivariate logistic regressions to determine factors associated with health insurance access among participants. Results The majority of participants (nearly 80%) were not currently enrolled in health insurance at the time of the study. Participants from rural regions were significantly more likely than urban participants to report difficulty using HI. Family members of participants from rural regions were more likely to have overall poor service quality through health insurance compared with family members of participants from urban regions. Overall, 37% of participants endorsed a lack of information about HI, nearly 22% of participants reported difficulty accessing HI, 22% reported difficulty using HI, and more than 20% stated they had trouble paying for HI. Older, more highly educated, and employed participants were more likely to have an easier time accessing HI than their younger, less well educated, and unemployed counterparts. HIV-positive participants were more likely to have sufficient information about health insurance options. Conclusions Our study highlights the dearth of health insurance utilization among MMT patients in northern Vietnam. It also sheds light on factors associated with increased access to and utilization of health insurance among this underserved population. These results can help improve health insurance enrollment among MMT patients, a population that is at increased need of financial assistance in accessing health services.

Abstract Background The expansion of methadone maintenance treatment in mountainous areas in still limited and little is known about its health impacts on drug users. This study aimed to examine health-related quality of life (HRQOL) and health care access among patients engaging in methadone maintenance treatment (MMT) in Tuyen Quang, a mountainous province in Vietnam. Methods We conducted a cross-sectional survey with 241 patients conveniently recruited in two MMT clinics (Son Duong and Tuyen Quang). EuroQol-5 Dimensions – 5 levels (EQ-5D-5 L) and Visual analogue scale (VAS) were employed to measure HRQOL. Multivariate logistic and tobit regressions were used to determine the factors associated with HRQOL and health care utilization. Results The overall mean score of the EQ-5D index and EQ-VAS were 0.88 (SD = 0.20) and 81.8% (SD = 15.27%), respectively. Only 8.7% utilized inpatient services, and 14.9% used outpatient services. Being more highly educated, suffering acute diseases, and using health service within the last 12 months were associated with a decreased EQ-5D index. Individuals who were multiple substance abusers and those who recently had inpatient care were more likely to have a lower VAS. Older respondents, those taking their medications at the more impoverished clinic, substance abusers, and individuals who were struggling with anxiety/depression or their usual daily activities were more likely to use both inpatient and outpatient care. Conclusions In summary, we observed good HRQOL, but high prevalence of anxiety/depression and low rates of service utilization among MMT patients in Tuyen Quang province. To improve the outcomes of MMT services in mountainous areas, it is necessary to introduce personalized and integrative services models with counseling and interventions on multiple substance use.