Brunenders: a partially attenuated historic poliovirus type I vaccine strain

Abstract

Brunenders, a type I poliovirus (PV) strain, was developed in 1952 by J. F. Enders and colleagues through serial in vitro passaging of the parental Brunhilde strain, and was reported to display partial neuroattenuation in monkeys. This phenotype of attenuation encouraged two vaccine manufacturers to adopt Brunenders as the type I component for their inactivated poliovirus vaccines (IPVs) in the 1950s, although today no licensed IPV vaccine contains Brunenders. Here we confirmed, in a transgenic mouse model, the report of Enders on the reduced neurovirulence of Brunenders. Although dramatically neuroattenuated relative to WT PV strains, Brunenders remains more virulent than the attenuated oral vaccine strain, Sabin 1. Importantly, the neuroattenuation of Brunenders does not affect in vitro growth kinetics and in vitro antigenicity, which were similar to those of Mahoney, the conventional type I IPV vaccine strain. We showed, by full nucleotide sequencing, that Brunhilde and Brunenders differ at 31 nucleotides, eight of which lead to amino acid changes, all located in the capsid. Upon exchanging the Brunenders capsid sequence with that of the Mahoney capsid, WT neurovirulence was regained in vivo, suggesting a role for the capsid mutations in Brunenders attenuation. To date, as polio eradication draws closer, the switch to using attenuated strains for IPV is actively being pursued. Brunenders preceded this novel strategy as a partially attenuated IPV strain, accompanied by decades of successful use in the field. Providing data on the attenuation of Brunenders may be of value in the further construction of attenuated PV strains to support the grand pursuit of the global eradication of poliomyelitis.

Cold-Adapted Viral Attenuation (CAVA): Highly Temperature Sensitive Polioviruses as Novel Vaccine Strains for a Next Generation Inactivated Poliovirus Vaccine

“…The highly temperature sensitive poliovirus strains were derived from, Brunenders, a Type I partially-attenuated poliovirus [ 38 ], by serial passage in vitro . The passaging was performed 34 times in PER.C6 cells at low temperature (26–30°C), at low Multiplicity of Infection (MOI = 0.01) and harvested 3–4 days post infection.…”

“…All remaining viruses used were rescued via RNA transfection for which the RNA was transcribed in vitro with a T7 polymerase using a synthetic cDNA plasmid as a template, as described previously [ 38 , 62 ]. The cDNA plasmids were synthetically generated at Genscript and contained the entire viral genome sequence downstream of a T7 promoter.…”

“…Sequencing of the full viral genomes was performed by RT-PCR and Sanger sequencing as described previously [ 38 ].…”

Production of high titer attenuated poliovirus strains on the serum-free PER.C6® cell culture platform for the generation of safe and affordable next generation IPV

“…Viruses: Sabin 1, 2 and 3 virus stocks were generated by performing two passages of Sabin 1, 2 and 3 viruses purchased at NIBSC (cat#01/528, 01/130 and 01/532, respectively) in adherent Vero cells at 32.5°C. cIPV vaccine strains (Mahoney, MEF-1 and Saukett) and rationally-attenuated (S19, MonoCre and MonoCreX) virus stocks were generated by transfection of synthetically derived PV genomic RNA, as described previously [18,19]. Viruses were scaled up in PER.C6 ® cells and all stocks were sequenced to confirm identity and the presence of attenuating mutations.…”

The application of virus-like particles as vaccines and biological vehicles

“…However, several deficiencies still exist in the use of inactivated and attenuated vaccines. For example, there is a security issue that attenuated vaccines may enhance pathogenicity by reverting to a wild-type phenotype in vaccined individuals, although effective immune responses can be induced by such vaccines (Burns et al 2014;Esteves 1988;Fachinger et al 2008;Horaud 1993;Sanders et al 2015;Wang et al 2014). Inactivated vaccines cannot replicate in vivo after inoculation; however, acquiring full protection after a single immunization by such vaccines will be difficult (Bright et al 2007).…”