ObjectiveTo investigate the difference of pathogenicity between the two genotypes of human metapneumovirus(hMPV) for the further research.MethodsAt various time after hMPV infection in BALB/c mice,viral titers of lung tissue were measured by real-time RT-PCR,pathology was assessed by a histopathological scoring system,airway responsiveness was assayed by animal lung function monitoring equipment.Pathogenicity was then measured by detailed evaluation through the results above.Results There is no significant difference in weight of mice between control group and experimental group through dynamic monitoring ; though the difference was exists in airway responsiveness and pathological changes of mice between control group and experimental group,the differences were not statistically in airway reaction,pathological changes and virus drops among the three groups of experimental group.ConclusionThere is no difference in pathogenicity between the two subtypes of hMPV in infection of BALB/c mice,viral genotype do not appear to be associated with pathogenicity.

Objective:To investigate the effect of distilled water on the viability of human lens epithelial cells (LECs) cultured in vitro. Methods:A total of 156 anterior capsule specimens were collected from 156 patients (156 eyes) who were diagnosed with age-related cataract during phacoemulsification combined with intraocular lens implantation from May to December 2020 in Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School.The 156 specimens were divided into 312 small pieces.Of the 312 pieces, 157 pieces were divided into normal control group (23 pieces), positive control group (10 pieces), balanced salt solution (BSS) immersion group (61 pieces) and distilled water immersion group (63 pieces) using computer-generated random numbers.Normal control group received no treatment.Positive control group was directly fixed with a mass fraction of 4% histiocytes fixative solution.For the 61 pieces in BSS immersion group, 20 pieces were soaked for 1 minute, 21 pieces for 2 minutes, and 20 pieces for 3 minutes.For the 63 pieces in distilled water immersion group, 20 pieces were soaked for 1 minute, 23 pieces for 2 minutes, and 20 pieces for 3 minutes.Another 125 pieces were selected to simulate the cataract aspiration-irrigation according to the treatment in BSS immersion group and distilled water immersion group respectively, plus rinse in a bottle containing BSS at a height of 70 cm for 1 minute.Cell viability was detected by trypan blue-eosin staining.LECs density, dead cell count, cell death rate and percentage of shedding (%) were calculated.Of the remaining 30 pieces, every 15 pieces were divided into normal control group, BSS immersion group, and distilled water immersion for 1, 2 and 3 minutes groups, with 3 pieces in each group.BSS immersion group was immersed for 3 minutes, and the other four groups were treated as mentioned above, and the LECs structure of the four groups was observed by light microscopy and transmission electron microscopy.This study adhered to the Declaration of Helsinki.The study protocol was approved by the Ethics Committee of Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School (No.2019-248-01). Written informed consent was obtained from each subject.Results:The boundaries of LECs in BSS treatment groups were clear, and there was no significant difference in morphology compared with normal control group.With time increasing, LECs in distilled water treatment groups gradually swelled, and the boundaries of dead cells were not clear.There were significant differences in LECs density, dead LECs count and LECs mortality ( F=13.459, 98.918, 130.600; all at P<0.001). The LECs density was lower in 2-minute and 3-minute distilled water treatment groups than in normal control group, showing statistically significant differences (both at P<0.05). The dead LECs count and LECs mortality were higher in 1-minute, 2-minute and 3-minute distilled water treatment groups than in normal control group and BSS treatment groups for the same time, and the differences were statistically significant (all at P<0.05). Only a few shed LECs were seen in normal control group, 1-minute, 2-minute and 3-minute BSS treatment groups, and BSS immersion combined rinse group.After different time of soaking, there were more shed LECs in distilled water immersion combined rinse group, and the range of LECs shedding increased with the extension of distilled water immersion.There was a significant difference in the shedding percentage of LECs among different groups ( F=123.670, P<0.001). The shedding percentages of LECs at different time points were higher in distilled water immersion groups and distilled water immersion combined rinse groups than in normal control group, and the difference was statistically significant (all at P<0.05). The shedding percentage of LECs increased significantly in distilled water immersion groups with the extension of immersion.Light microscopy showed that the cells were destroyed in 1-minute, 2-minute and 3-minute distilled water treatment groups, and some LECs shed in the 2-minute and 3-minute treatment groups.Transmission electron microscopy showed cell lysis and destruction, suborganelles swelling, disruption of intercellular junctions in 1-minute, 2-minute and 3-minute distilled water treatment groups, loose attachment between cells and capsule in the 2-minute and 3-minute treatment groups, and cell detachment from capsule in the 3-minute treatment group. Conclusions:Distilled water immersion leads to LECs death in a time-dependent manner, and distilled water immersion combined with rinse can remove LECs on the lens capsule.