Anti-virus Effect Of RSV-IGIV

[Objective]Respiratory syncytial virus (RSV) infection causes bronchiolitis and viral pneumonia in infants and children, especially infants under 2 years of age. RSV commonly induces and exacerbates asthma. It also aggravates chronic bronchitis in elder and causes lower respiratory track infection in immunocompromised patients. But there is no effective vaccine and drug to prevent and treat RSV infection until now. Now RSV-IGIV and Palivizumab are used to treat RSV infection in abroad. Because RSV-IGIV and Palivizumab are too expensive, the research of national RSV-IGIV is valuable. The objective of this research was to investigate the effect of RSV-IGIV on RSV replication in vivo and the therapeutic effect on RSV infection in mice. [Methods]1. The antivirus neutralization was used to study the neutralization titer of RSV-IGIV, IGIV and Palivizumab.2. The microdose cytopathogenic inhibition assay (MCIA) was used to observe the effect of RSV-IGIV on RSV replication.(1)Duplication of RSV was inhibited directly. After Hep-2 cell were attacked by 100TCID₅₀ RSV for 90min, RSV-IGIV, IGIV, ribavirin and RSV-IGIV mixed ribavirin of different concentrations were added into it, and CPE was observed;(2)Absorption of RSV was inhibited. After three kinds of antibody of differentconcentrations was added for 90min, Hep-2 cell was attacked by 100TCID₅₀RSV for90min, and CPE was observed;(3)RSV was inactivated directly. After three kinds of antibody of different concentrations and 100TCID₅₀RSV were mixed for 90min, Hep-2 cell were infected by it, CPE was observed.3. The 150 mice were divided into two groups at random: treatment group and control group. In treatment group and virus control group, BALB/c mice were infected by nasal drip of 0.2ml of RSV (TCID₅₀:10^-4.2/100 n l). In drug toxicity group and normal control group, BALB/c mice were not infected.Each groups mice were killed on day 6, 8 respectively and were isolated the virus, determined by immunofluorescence and performed pathological examination of the lung tissue. [Results]1 The neutralization titer of RSV-IGIVThe neutralization titer of RSV-IGIV, IGIV and palivizumab was 1:256s 1:50, 1:347 respectively. The neutralization titer of RSV-IGIV was about 5 times of IGIV and lower than that of palivizumab.2 RSV-IVIG inhibition RSV(1)Duplication of RSV was inhibited directly. When the concentration of RSV-IGIV reached 6.25 u g/ml, CPE was negative after cell was infected with RSV for 90min. There was significant difference between virus group and RSV-IGIV group (P<0.05).(2)Absorption of RSV can be inhibited. When the Concentration of RSV-IGIV reached 12.5 u g/ml, CPE was negative after cell was infected with RSV for 90min. There was significant difference between virus group and RSV-IGIV group (P<0.05).(3)RSV was inactivated directly.When the concentration of RSV-IGIV reached 6.25 g/ml, CPE was negative .There was significant difference between virus group and RSV-IGIV group (P<0.05).3 Anti-virus effect of RSV-IGIV in vivo3.1 The histological changes of lung in mice3.1.1 Results of Light microscopeMice were killed at the 6th , 8th day after they were infected by RSV, and lung tissue was stained by HE.?Normal lung showed that structural arrangement was clear. There was no thick of alveoli wall and no infiltration of mononuclear cell.?In virus group, the alveoli wall was obvious thickening. Mass lymphocytes infiltrated and alveoli of lung became small. The most significant damage of lung tissue was displayed at the 6th day, and improved gradually after 8th day.?Compared with virus group, the pathological scored of the lung tissue in RSV-IGIV group was lower than that of virus control group significantly (P<0.01) at the 6th, 8th day, respectively. Compared with IGIV group, the pathological scored of the lung tissue was lower obviously at the 6th day (P<0.05).?There was no significant difference between control group and drug toxicity group.3.1.2 Results of electron microscopeAt the 6th day after the mice were treated with different drugs, ultrathin section of lung tissue in virus control group revealed epithelia I swelling, the alveoli wall edema, the lymphocytes and the acido phileleukocyte infiltration, vascular endotheliocyte edema. Mononuclear cell and red blood cell were detected in the adveoli of lung. Compared with virus control group, lung tissue injuries were significantly diminished in RSV-IGIV treatment group and palivizumab treatment group. 4 Results of virus isolation and immunofluorescenceThe positive ratio of virus isolation and immunofluorescence in RSV-IGIV group were lower than that of virus control group significantly (P<0.0\), and lower than that of IGIV group (P<0.05)^ ribavirin group (PO.01). There was no significant difference between RSV-IGIV group and palivizumab group (P>0. 05). [Conclusion]1. The neutralization titer of RSV-IGTV was higher than that of IGIV and lower than that of palivizumab.2. RSV-IGIV could inactivate directly RSV, inhibite the duplication of RSV in vitroand inhibite the adsorption of RSV.3. RSV-IGIV was effective in the treatment on RSV infection. It could lessen the...