Pre-Clinical Development of BCG.HIVACAT, an Antibiotic-Free Selection Strain, for HIV-TB Pediatric Vaccine Vectored by Lysine Auxotroph of BCG

Abstract

In the past, we proposed to develop a heterologous recombinant BCG prime-recombinant modified vaccinia virus Ankara (MVA) boost dual pediatric vaccine platform against transmission of breast milk HIV-1 and Mycobacterium tuberculosis (Mtb). In this study, we assembled an E. coli-mycobacterial shuttle plasmid pJH222.HIVACAT expressing HIV-1 clade A immunogen HIVA. This shuttle vector employs an antibiotic resistance-free mechanism based on Operator-Repressor Titration (ORT) system for plasmid selection and maintenance in E. coli and lysine complementation in mycobacteria. This shuttle plasmid was electroporated into parental lysine auxotroph (safer) strain of BCG to generate vaccine BCG.HIVACAT. All procedures complied with Good Laboratory Practices (GLPs). We demonstrated that the episomal plasmid pJH222.HIVACAT was stable in vivo over a 20-week period, and genetically and phenotypically characterized the BCG.HIVACAT vaccine strain. The BCG.HIVACAT vaccine in combination with MVA.HIVA induced HIV-1- and Mtb-specific interferon γ-producing T-cell responses in newborn and adult BALB/c mice. On the other hand, when adult mice were primed with BCG.HIVACAT and boosted with MVA.HIVA.85A, HIV-1-specific CD8+ T-cells producing IFN-γ, TNF-α, IL-2 and CD107a were induced. To assess the biosafety profile of BCG.HIVACAT-MVA.HIVA regimen, body mass loss of newborn mice was monitored regularly throughout the vaccination experiment and no difference was observed between the vaccinated and naïve groups of animals. Thus, we demonstrated T-cell immunogenicity of a novel, safer, GLP-compatible BCG-vectored vaccine using prototype immunogen HIVA. Second generation immunogens derived from HIV-1 as well as other major pediatric pathogens can be constructed in a similar fashion to prime protective responses soon after birth.

A neonatal oral Mycobacterium tuberculosis-SIV prime/intramuscular MVA-SIV boost combination vaccine induces both SIV and Mtb-specific immune responses in infant macaques

“…These compelling facts provided the rationale for the development of combination HIV-TB vaccines. In fact, based on murine TB efficacy data with a recombinant auxothroph BCG vaccine expressing an African consensus HIV-1 clade A Gag immunogen (rBCG.HIVA) (5–8), phase I clinical trials have been initiated in African neonates. The restriction of preclinical BCG-HIV immunogenicity and safety studies to murine models or adult macaques (5, 7–12), however, is problematic.…”

“…In fact, based on murine TB efficacy data with a recombinant auxothroph BCG vaccine expressing an African consensus HIV-1 clade A Gag immunogen (rBCG.HIVA) (5–8), phase I clinical trials have been initiated in African neonates. The restriction of preclinical BCG-HIV immunogenicity and safety studies to murine models or adult macaques (5, 7–12), however, is problematic. Substantial differences in i) infant and adult immune function, ii) immune development between neonatal mice and human newborns, and iii) inherent limitations of BCG-derived vaccines (importantly the safety risk for immunocompromised individuals and lack of relevant protective TB antigens), argue for the tandem pursuit of alternative regimens.…”

Analysis and Prospects of Using Recombinant Vaccinia Virus MVA Strain as a Vector in the Development of the Vaccines against Human and Simian Immunodeficiency Virus Diseases

“…поэтому чаще всего для бустирования применяется рекомбинантный вирус вакцины, штамм MVA, экспрессирующий иммунодоминантные антигены вич или вируса иммунодефицита обезьяны (вио). для праймирования могут применяться различные конструкции или их сочетания [6].…”

“…этот вектор имеет ряд преимуществ: его безопасность показана при вакцинации около 2 млрд человек, однако у иммунокомпромиссных лиц он может вызывать диссеминированное заболевание. поэтому, согласно рекомендациям воз, для иммунизации вич-инфицированных младенцев предлагается использовать лизиновый ауксотроф пастеровского штамма -AERAS-401 [6,9]. он менее вирулентен и более иммуногенен, что показано в опытах на мышах и морских свинках.…”

“…поскольку в ряде клинических испытаний по оценке режимов иммунизации против туберкулеза применялось праймирование вакциной BCG и бустирование рекомбинантным штаммом . MVA, экспрессирующим один из иммунодоминантных антигенов возбудителя туберкулеза 85а -MVA85а, то эти векторы выбраны для одновременной иммунизации против туберкулеза и вич [3,6]. при инъецировании штаммов MVA•HIVA85а установлено, что у иммунизированных мышей BALB/c индуцировался т-клеточный ответ и против HIVA, и против 85а антигена возбудителя туберкулеза [3].…”