The association of ABO and Rhesus blood type with the risks of developing SARS-CoV-2 infection: A meta-analysis

@#Coronavirus Disease 2019 (COVID-19) has been spreading like a wildfire everywhere in the globe. It has been challenging the global health care system ever since the end of 2019, with its virulence and pathogenicity. Recent studies have shown the association between ABO blood group, Rhesus blood type and susceptibility to COVID-19 infection. Various studies and few meta-analyses have been done and some might be inconsistent; therefore, this meta-analysis was done to assess the relationship between different ABO and Rhesus blood types on the susceptibility to COVID-19 infections. This meta-analysis assessed the odds ratio of COVID-19 infection of different ABO and Rhesus blood types. Subgroup analyses according to (1) age and gender matched; (2) different blood group antigens; (3) Rhesus positive and negative of each blood group were carried out. Publication bias and Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) were also done to assess the risk of bias in these publications. It was found that blood group A showed significant difference in odds ratio of COVID-19 infection (OR, 1.16; 95% CI, 1.08-1.24). Blood group AB showed significant difference in odds ratio when studies with lower QUADAS-2 score were removed. This means that populations with blood group A and AB are more likely to be infected with COVID-19. As there is a higher tendency that blood group A and AB to be infected with COVID19, precautious care should be taken by these populations.

Distribution of pathogenic Leptospira in environmental water and soils of selected recreational forests in Perak, Malaysia

@#Leptospirosis is an emerging zoonotic disease endemic in tropical regions. Aiming at assessing the potential infection risks via recreational exposure, the molecular prevalence of pathogenic Leptospira in 14 amenity forests in five selected districts of the state of Perak was determined. Water and soil samples along streams and waterfalls were subjected to culture of leptospires and the pathogenic Leptospira spp. was detected by lipL32-based polymerase chain reaction (PCR). Twenty out of 154 samples (13%) that tested positive for leptospires were mostly soils and still water recorded with tolerable temperatures (22.226.5°C) and pHs (5.73-6.70). The localised prevalence was highly varied among eight positive forests (6.7-41.7%), particularly higher in Kampar and Kinta districts which are the more populated urban areas. The importance of public health surveillance should not be underrated given the high prevalence of Leptospira spp. in forests in close proximity to indigenous settlements, even where the places are clean. Overall, this study discovered a wide distribution of pathogenic Leptospira spp. in recreational areas.

Viability of dengue virus in culture stocks is efficiently preserved by storage in diluted forms

@#Storage of dengue virus (DENV) culture stocks in -80°C is a common laboratory practice to maintain the viability of the virus for long-term usage. However, the efficiency of this method could still be hindered by multiple factors. In our laboratory, we observed a constant and substantial deterioration in the titer of DENV in Vero culture supernatant stored in -80°C. Such incident had badly hampered the laboratory work and prompted an investigation to determine the cause. DENV isolates representing all four serotypes were propagated and the culture supernatants were harvested and stored in aliquots of original stock and 10 fold dilutions (10-1 -10-4). DENV titer in these stocks was determined prior to storage and reassessed on the third and sixth month of storage by focus forming unit assay (FFUA). The result demonstrated a constant preservation of titer ranging from 104 ffu/ml to 105 ffu/ml in the diluted DENV virus culture stocks of 10-1, and 10-2 of DENV1-4, a minor reduction of titer from 103 ffu/ml to 102 ffu/ml at dilution 10-3 for DENV4 only and complete deterioration in undiluted culture stock and lower dilution (10-4) within 6 months of storage in -80°C for all serotypes. It is recommended that propagated DENV in Vero cells are stored in 10 fold dilutions as compared to the original form to preserve the titer for long-term usage.

IL-8 as a potential in-vitro severity biomarker for dengue disease

@#Dengue is a common infection, caused by dengue virus. There are four different dengue serotypes, with different capacity to cause severe dengue infections. Besides, secondary infections with heterologous serotypes, concurrent infections of multiple dengue serotypes may alter the severity of dengue infection. This study aims to compare the severity of single infection and concurrent infections of different combinations of dengue serotypes in-vitro. Human mast cells (HMC)-1.1 were infected with single and concurrent infections of multiple dengue serotypes. The infected HMC-1.1 supernatant was then added to human umbilical cord vascular endothelial cells (HUVEC) and severity of dengue infections was measured by the percentage of transendothelial electrical resistance (TEER). Levels of IL- 10, CXCL10 and sTRAIL in HMC-1.1 and IL-8, IL-10 and CXCL10 in HUVEC culture supernatants were measured by the ELISA assays. The result showed that the percentage of TEER values were significantly lower in single infections (p< 0.05), compared to concurrent infections on day 2 and 3, indicating that single infection increase endothelial permeability greater than concurrent infections. IL-8 showed moderate correlation with endothelial permeability (r > 0.4), indicating that IL-8 may be suitable as an in-vitro severity biomarker. In conclusion, this in-vitro model presented few similarities with regards to the conditions in dengue patients, suggesting that it could serve as a severity model to test for severity and levels of severity biomarkers upon different dengue virus infections.

Ultrastructural changes of cell morphology and viral morphogenesis of two ecotypes of dengue virus infection in human monocytic U-937 cell

@#Dengue virus (DENV) is maintained and circulated in both sylvatic/enzootic and endemic/human cycles and spill over infection of sylvatic DENV into human populations has been reported. Extensive deforestation and increase human activities in forest may increase the risk of human exposure to sylvatic dengue infection and this may become a threat to human. Present study investigated the changes in cell morphology and viral morphogenesis upon infection with sylvatic and endemic ecotypes in human monocytic U-937 cells using transmission electron microscopy. Autophagy, a process that is either pro-viral or anti-viral, was observed in U-937 cells of both infections, however only the replication of endemic DENV was evidenced. An insight into the infection responses of sylvatic progenitors of DENV in susceptible host cells may provide better understanding on dengue emergence in human populations.