[Protective activity of Immunovac-VP-4 vaccine against avian influenza virus H5N2 administered by different methods].
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AIM To experimentally assess protective effect of Immunovac-VP-4 vaccine against avian influenza virus H5N2. MATERIALS AND METHODS. Immunization of mice with polycomponent vaccine Immunovac-VP-4 was performed using oral or mucosal route of administration (intranasally, orally, and with combined nasal-oral method). Immunized mice were inoculated intranasally by influenza virus H5N2 adapted for mice. Survival of mice in experimental and control (intact) groups was assessed daily during 14 days. Survival and death rates of mice were determined. Levels of cytokines in sera of mice from both groups were measured by enzyme immunoassay. RESULTS Half of experimental animals survived after triple subcutaneous administration of vaccine in dose 20 mcg and subsequent intranasal challenge with avian influenza virus H5N2. Single subcutaneous immunization with dose 400 mcg resulted in survival of 80 +/- 12.6% of mice after challenge. Triple intranasal and combined intranasal-oral immunization as well as after triple subcutaneous immunization resulted in survival of half of challenged mice. In control group challenge was lethal for 90 - 100% of mice. Same methods of immunization lead to increase of IL-6, IL-12, IL-15, and IFN-gamma levels. CONCLUSION Data about significant protective effect after immunization with Immunovac-VP-4 against avian influenza virus H5N2 were obtained. Immunovac-VP-4 administered by mentioned routes activated nasal-associated lymphoid tissue providing first line defense at entry site of influenza infection, which demonstrates need to further study of this vaccine during development of strategy for non-specific prophylaxis of influenza infection.Keywords:
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Abstract Background Influenza virus continues to cause significant hospitalization rates in infants and young children. A 2-dose regime of trivalent inactivated vaccine is required to generate protective levels of hemagglutination inhibiting (HAI) antibodies. A vaccine preparation with enhanced immunogenicity is therefore desirable. Methods Mice were inoculated intramuscularly (IM) with live and inactivated preparations of A/Wisconsin/67/2005 (H3N2). Serum cytokine levels, hemagglutinin (HA)-specific antibody responses and nucleoprotein (NP)-specific CD8+ T cell responses were compared between vaccinated groups, as well as to responses measured after intranasal infection. The protective efficacy of each vaccine type was compared by measuring virus titers in the lungs and weight loss of mice challenged intranasally with a heterosubtypic virus, A/PR/8/34 (H1N1). Results Intramuscular administration of live virus resulted in greater amounts of IFN-α, IL-12 and IFN-γ, HA-specific antibodies, and virus-specific CD8+ T cells, than IM immunization with inactivated virus. These increases corresponded with the live virus vaccinated group having significantly less weight loss and less virus in the lungs on day 7 following challenge with a sublethal dose of a heterosubtypic virus. Conclusions Inflammatory cytokines, antibody titers to HA and CD8+ T cell responses were greater to live than inactivated virus delivered IM. These increased responses correlated with greater protection against heterosubtypic virus challenge, suggesting that intramuscular immunization with live influenza virus may be a practical means to increase vaccine immunogenicity and to broaden protection in pediatric populations.
Inactivated vaccine
Hemagglutination assay
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Objective To observe immune responses and heterosubtypic protection elicited by an inactivated influenza H5N1 vaccine with different immunization routes in mice. Methods BALB/c mice were intraperitoneally injected or intranasally immunized with the inactivated H5N1 vaccine, the mice administered with PBS were used as control. Weight loss and survival in mice were observed after PR8 or a H9N2 virus challenge. Serum specific IgG antibody and its subclasses were detected by ELISA kits. Ratios of CD4+ /CD8+ lymphocytes in spleens of mice were assayed. The t-test was used in the comparison of different groups.Results After challenge, weight loss was found in all groups, but the weight of mice in vaccination groups returned to normal later. The mice in PBS groups all died. The vaccinated mice were completely protected against PR8 and partly protected against H9N2 virus. The level of IgG antibody increased significantly after vaccination, and the increase magnitude of IgG2a was higher than that of IgG1. The ratios of CD4+ /CD8+ lymphocytes in spleens of vaccinated mice decreased after challenge (t=6. 8017,P<0. 01) , especially in the intranasal group (t = 3. 9701, P < 0. 05 ). Conclusions Both intraperitoneal injection and intranasal immunization can induce a high level of specific IgG, especially the level of IgG2a, and provide protection against heterosubtypic viruses. Intranasal immunization seems to induce a higher level of CD8+ T cell response.
Key words:
Influenza A virus,H5N1 subtype; Influenza vaccine; Injections,intraperitoneal; Administration,intranasal; Cross protection
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A challenge study was conducted to evaluate the safety and efficacy of an inactivated influenza H3N2 virus vaccine combined with Quil A/Alhydrogel mixture under controlled conditions in piglets. Twenty-four piglets from 12 sows were allocated to 2 groups; injected intramuscularly with 2 doses of the tested vaccine or with PBS at 2 wk intervals and challenged intratracheally with 105TCID50 of the H3N2 swine influenza virus 6 d after the 2nd immunization. Clinical and virological parameters were recorded for 4 d after the challenge. The use of the tested vaccine produced high serum hemagglutination-inhibition titers against the swine H3N2 strain virus. This strong immune response suppressed all clinical signs and viral shedding and reduced pulmonary lesions due to the challenge in the vaccinated group, without causing any secondary effects. Our results suggest that the serum HI titers correlated with the degree of protection induced by an inactivated swine influenza H3N2 vaccine.
Hemagglutination assay
Viral Shedding
Inactivated vaccine
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Intraperitoneal injection
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Oral route
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To investigate the seasonal influenza split vaccine's immune protective effectiveness against the homologous and heterogonous subtypes of influenza A virus challenge and the relationship between the protective effectiveness and hemagglutination inhibition (HI) antibody titer in mice. Two components of H1N1 and H3N2 in Chinese 2008-2009 seasonal influenza spilt vaccine, were derived from vaccine strain A/Brisbane/59/2007 (H1N1)-like virus and A/Brisbane/10/2007 (H3N2)-like virus respectively, and were used to immune BALB/c mice. Firstly, different doses of the vaccines were used to immunize mice and the HA immunization dosage that can induce the HI antibody titer of 40 in mice was identified; Secondly, H1N1 vaccine immunized mice were challenged with different doses of influenza virus mouse adaptation strains of A/Brisbane/59/2007 (H1N1)-like virus (MA) (referred to as A1 virus, well matched-strain in the homologous subtype) and A/Purto Rico/8/34 (H1N1) (referred to as PR8 virus, poor matched-strain in the homologous subtype) respectively, and H3N2 vaccine immunized mice were challenged with H1N1 influenza virus of A1 strain (Heterogonous subtype), body weight changes and survival rates were observed to explore the immune protective effectiveness of influenza split vaccine against the homologous and heterogonous subtypes of influenza A virus in mice. Results indicated that HI antibody titers were elevated as the HA protein immunization dosages increased from 0.15 microg, 0.5 microg, 1.5 microg, 5 microg to 15 microg in mice, and 1.5 microg HA of the seasonal influenza split vaccine could induced HI antibody titer of 40 in mice; 3LD50, 10LD50, 30LD50, 100LD50, 300LD50,1000LD50 and 3000LD50 of influenza virus strain A1 were used to challenge the H1N1 immunization mice, 1.5 microg HA of H1N1 vaccine could 100% protect mice against challenge with 1000LD50 of matched and homologous subtype of influenza virus strains A1, mice immunized with 15 microg HA of H1N1 vaccine even could 100% protect mice against challenge with 3000LD50 of influenza virus strains A1; but mice immunized with both the 1.5 microg and 15 microg HA of H1N1 vaccine were all sacrificed when challenged with 3LD50 of the mismatched and homologous subtype of influenza virus strain PR8, and mice immunized with the high dosage of 15 microg HA of H3N2 vaccine also were all sacrificed when challenged with 3LD50 of the heterogonous subtype of influenza virus strain A1. These results suggest that 1.5 microg HA of seasonal influenza split vaccine could induced HI antibody titer of 40 after one dose in mice, this dosage of HA can effectively protect mice against matched homologous subtype of influenza virus strain, but hardly to protect mice against mismatched homologous or heterogonous subtype of influenza virus strain. These results provide materials for the establishment of influenza vaccine evaluation system based on seasonal influenza vaccine.
Hemagglutination assay
Antibody titer
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Heterologous
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Influenza is one of the critical infectious diseases globally and vaccination has been considered as the best way to prevent. In this study, immunogenicity and protection efficacy between intranasal (IN) and microneedle (MN) vaccination was compared using inactivated swine-origin influenza A/H1N1 virus vaccine. Mice were vaccinated by MN or IN administration with 1 μg of inactivated H1N1 virus vaccine. Antigen-specific antibody responses and hemagglutination-inhibition (HI) titers were measured in all immunized sera after immunization. Five weeks after an immunization, a lethal challenge was performed to evaluate the protective efficacy. Furthermore, mice were vaccinated by IN administration with higher dosages (> 1 μg), analyzed in the same manner, and compared with 1 μg-vaccine-coated MN. Significantly higher antigen-specific antibody responses and HI titer were measured in sera in MN group than those in IN group. While 100% protection, slight weight loss, and reduced viral replication were observed in MN group, 0% survival rate were observed in IN group. As vaccine dose for IN vaccination increased, MN-immunized sera showed much higher antigen-specific antibody responses and HI titer than other IN groups. In addition, protective immunity of 1 μg-MN group was similar to those of 20- and 40 μg-IN groups. We conclude that MN vaccination showed more potential immune response and protection than IN vaccination at the same vaccine dosage.
Hemagglutination assay
Antibody titer
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