Evaluation Of The Immune Effect Of Nanospheres On IBRV Inactivated Vaccine

Infectious bovine rhinotracheitis(IBR)is a bovine febrile-type acute infectious disease caused by Bovine herpesvius 1(BHV-1),also known as"red nose disease"or"necrotic rhinitis."IBRV is one of the major pathogens causing bovine respiratory syndrome.At present,the prevention and control of IBR in the country mainly depends on inactivated vaccines,and there are many drawbacks,for example,when the virus is inactivated with the conventional inactivated formaldehyde,the structure of the natural protein on the virus surface changes,resulting in poor results after immunization,as well as the short duration of immune protection,it is difficult to achieve a satisfactory immune effect.Therefore,the search for a new type of safe and non-irritating inactivating agent and a vaccine adjuvant capable of effectively prolonging the period of immune protection has become an urgent problem to be solved in the development of the inactivated vaccine.The purpose of this study is to explore the inactivation effect and safety of a new type of inactivating agent for formaldehyde,povidone-iodine,and to track the immunoadjuvant effect of nanospheres on IBR inactivated vaccines through animal experiments.In this study,the optimal inactivation conditions for povidone-iodine and formaldehyde were determined by two factors:inactivation time and inactivation concentration.Three groups of cells were blinded to observe CPE,sterility test and trypan blue staining to find the best inactivation concentration and inactivation time of the new inactivating agent.The results showed that 8%of povidone-iodine can completely inactivate IBRV for 48 h,and 0.3%of formaldehyde can completely inactivate IBRV for 48 h.In order to determine the toxicity of povidone-iodine to cells,in this study,different concentrations of povidone iodine and formaldehyde were added to MDBK cell culture medium to compare their cytotoxic effects on MDBK.The results showed that 0.5%of formaldehyde caused the death of most cells,while 18%of povidone-iodine had no toxicity to cells,up to 20%toxicity to cells leads to partial cell death.The above results show that povidone-iodine can completely inactivate IBRV,and it is less toxic to cells than formaldehyde,and can replace inactivated formaldehyde to prepare inactivated vaccine.To investigate the immunopotentiating effect of polystyrene nanospheres(PS)as an adjuvant,carrying IBRV.In this study,EDC-activated polystyrene microspheres were used to bind IBRV in one step and inactivate the coupled IBRV to prepare inactivated vaccine-infected Kunming mice.The serum IgG was detected by indirect ELISA.The results showed that the PS+206 adjuvant group had the highest antibody level and the longest duration of immunity,compared with 206 adjuvant group,inactivated vaccine+PS group and PS control group,the difference was statistical difference(P<0.01).The dynamic changes of CD4~+and CD8~+cells in blood were detected by flow cytometry.The results showed that the percentage of CD4~+and CD8~+T cell subsets in the blood of mice injected with the PS+206 adjuvant group was the highest among the total lymphocytes,and the duration was the longest,compared with the 206 adjuvant group,the difference was statistical difference(P<0.01).The results of serum IFN-?,IL-4 and IL-6 showed that the content of three cytokines was the highest in the PS+206 group and the longest duration,compared with 206 adjuvant group,inactivated vaccine+PS group and PS control group,the difference was statistical difference(P<0.01).The above results show that PS as an adjuvant can improve the immune effect of adjuvant 206,and can prolong the duration of immunity,and overcome the shortcomings of the traditional immune inactivated vaccine.In summary,povidone iodine oral solution can replace IBRV to replace formaldehyde,providing a new direction for exploring ideal virus inactivated.PS as an adjuvant can increase the immune effect of inactivated vaccine and prolong the duration of immunity.This provides a direction for the development of highly effective inactivated vaccines.