Generation of influenza vaccine viruses on Vero cells by reverse genetics: an H5N1 candidate vaccine strain produced under a quality system

ABSTRACTIn this study, we assessed in humans the immunogenicity and safety of one dose (7.5 or 15 μg of hemagglutinin [HA]) of a whole-virion inactivated prepandemic influenza vaccine adjuvanted with aluminum hydroxide. The vaccine strain was made by reverse genetics from the highly pathogenic avian A/Chicken/Astana/6/05 (H5N1) clade 2.2 strain isolated from a dead bird in Kazakhstan. The humoral immune response was evaluated after a single vaccination by hemagglutination inhibition (HI) and microneutralization (MN) assays. The vaccine was safe and immunogenic, inducing seroconversion in 55% of the evaluated patients, with a geometric mean titer (GMT) of 17.1 and a geometric mean increase (GMI) of 3.42 after a dose of 7.5 μg in the HI test against the vaccine strain. The rate of seroconversion increased up to 70% when the dose of 15 μg was used. The percentages of individuals achieving anti-HA titers of ≥1:40 were 52.5% and 57.5% for the 7.5- and 15-μg dose groups, respectively. Similar results were obtained when antibodies were analyzed in an MN test. Substantial cross-neutralization titers (seroconversion in 35% and 52.5% of subjects in the two dose groups, respectively) were detected against heterologous clade 1 strain NIBRG14 (H5N1). Thus, one dose of this whole-virion prepandemic vaccine adjuvanted with aluminum has the potential to be effective against H5N1 viruses of different clades.

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Immunogenicity and Efficacy Evaluation of Vero Cell-Adapted Infectious Bursal Disease Virus LC-75 Vaccine Strain in Ethiopia

10.21203/rs.3.rs-310833/v1 ◽

2021 ◽

Author(s):

Wakjira Kebebe ◽

Molalegne Bitew ◽

Fufa Dawo ◽

Bedaso Mammo ◽

Hawa Mohammed ◽

...

Keyword(s):

Vero Cell ◽

Disease Virus ◽

Vaccine Strain ◽

Infectious Bursal Disease Virus ◽

Chicken Embryo Fibroblast ◽

Vero Cells ◽

Infectious Bursal Disease ◽

Efficacy Evaluation ◽

Viral Pathogen ◽

Bursal Disease

Abstract Background: Infectious bursal disease virus (IBDV) is an avian viral pathogen that causes infectious bursal disease (IBD) of chickens. The disease is endemic in Ethiopia since 2002 and vaccination is the major means of disease prevention and control. IBD vaccine is produced in Ethiopia using primary chicken embryo fibroblast (CEF) cell; which is time-consuming, laborious, and uneconomical. The present study was carried out to develop cell-based IBDV LC-75 vaccine using Vero cells, and to evaluate the immunogenicity and protection level.Results: Identity of the vaccine seed was confirmed using gene-specific primers using reverse transcription polymerase chain reaction. Confluent monolayer of Vero cells was infected with vaccine virus and serial passage continued till passage ten. Characteristic virus induced cytopathic effect was observed starting from passage 2 on the third day post-infection. The infectious titer of adapted virus showed a linear increment along the passage level. Virus induced specific antibody was determined using indirect ELISA after vaccination of 14 days old chicks through ocular route. Accordingly, the antibody titer measured from Vero cells vaccinated chicks revealed similar level with the currently available CEF cell-based vaccine. Chicks vaccinated with Vero cell adapted virus showed complete protection against very virulent IBDV, while unvaccinated group had 60% morbidity and 25% mortality.Conclusions: The IBDV vaccine strain well adapted on Vero cells and found to be immunogenic induces antibodies development and successfully protects chicks against challenging with the circulating field IBDV isolate. Hence, it is recommended to produce IBD vaccine using Vero cell culture with enough quantity to conquer the limitations using CEF cells and thus to vaccinate chicks to protect against IBDV infection.

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Antigenic assessment of the H3N2 component of the 2019-2020 Northern Hemisphere influenza vaccine

10.1101/2020.01.28.20019281 ◽

2020 ◽

Author(s):

Sigrid Gouma ◽

Madison Weirick ◽

Scott E. Hensley

Keyword(s):

Influenza Vaccine ◽

Northern Hemisphere ◽

Vaccine Strain ◽

Antibody Responses ◽

Wild Type ◽

H3n2 Vaccine

AbstractThe 2019-2020 Northern Hemisphere influenza vaccine includes antigens from 3c3.A H3N2 viruses; however, over half of circulating H3N2 viruses belong to subclade 3c2.A1b. Here, we analyzed antibody responses elicited by the egg-adapted 3c3.A H3N2 vaccine strain in ferrets and humans. We found that this vaccine strain elicits antibodies that have reduced reactivity to a wild-type 3c3.A strain and very limited reactivity to 3c2.A strains, including the currently circulating 3c2.A1b strain.

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