RESUMO
Newcastle Disease virus (NDV) has shown promise as an oncolytic virus for treatment of a wide range of tumours. NDV with a multi-basic cleavage site (MBCS) in the fusion (F) protein (NDV F3aa) has increased oncolytic efficacy in several tumour models, but also increased virulence in chickens compared to non-virulent NDV F0, raising potential environmental safety issues. Previously, we generated a variant of NDV F3aa with a disrupted V protein gene and a substitution of phenylalanine to serine at position 117 of the F protein (NDV F3aa-S-STOPV). Compared to NDV F3aa this virus had decreased virulence in embryonated chicken eggs. In this study, the virulence of the virus was evaluated upon inoculation of six-week-old chickens through a natural infection route and by determination of the intracerebral pathogenicity index (ICPI). Based on these data NDV F3aa-S-STOPV classified as a non-virulent virus. Although NDV F3aa was classified as a virulent virus based on the ICPI, the virus was also less pathogenic than NDV F0 upon inoculation of six-week-old chickens. These data indicate that NDV with a MBCS is not necessarily pathogenic in chickens. In addition, these data show that F3aa-S-STOPV is safe to use in viro-immunotherapies without posing a threat for chickens upon accidental exposure.
Assuntos
Doença de Newcastle , Doenças das Aves Domésticas , Animais , Galinhas , Vírus da Doença de Newcastle/genética , Proteínas Virais de Fusão/genética , Proteínas Virais de Fusão/metabolismo , Virulência/genéticaRESUMO
The influenza A virus nucleoprotein (NP) and matrix protein are major targets for human virus-specific cytotoxic T-lymphocyte (CTL) responses. Most of the CTL epitopes that have been identified so far are conserved. However, sequence variation in CTL epitopes of the NP has recently been demonstrated to be associated with escape from virus-specific CTLs. To assess the extent of variation in CTL epitopes during influenza A virus evolution, 304 CTL clones derived from six study subjects were obtained with specificity for an influenza A/H3N2 virus isolated in 1981. Subsequently, the frequency of the CTL clones that failed to recognize a more recent influenza virus strain isolated in 2003 was determined. In four of six study subjects, CTLs were found to be specific for variable epitopes, accounting for 2.6 % of all CTL clones. For some of these CTL clones, the minimal epitope and the residues responsible for abrogation of T-cell recognition were identified.
Assuntos
Variação Antigênica , Linfócitos T CD8-Positivos/imunologia , Epitopos de Linfócito T/genética , Vírus da Influenza A/imunologia , Nucleoproteínas/genética , Proteínas de Ligação a RNA/genética , Linfócitos T Citotóxicos/imunologia , Proteínas do Core Viral/genética , Sequência de Aminoácidos , Células Clonais , Epitopos de Linfócito T/imunologia , Humanos , Vírus da Influenza A Subtipo H3N2/genética , Vírus da Influenza A Subtipo H3N2/imunologia , Vírus da Influenza A/classificação , Vírus da Influenza A/genética , Proteínas do Nucleocapsídeo , Nucleoproteínas/imunologia , Proteínas de Ligação a RNA/imunologia , Proteínas do Core Viral/imunologiaRESUMO
The use of cytotoxic T lymphocyte (CTL)-inducing vaccines could afford both homo- and heterosubtypic immunity. However, amino acid variation in CTL epitopes associated with escape from CTL-mediated immunity might undermine the use of these vaccines. To assess the impact of amino acid substitutions in highly conserved epitopes on viral fitness and recognition by specific CTL, we performed a mutational analysis of various CTL epitopes. Our findings indicated that fitness costs limited variation in functionally constrained epitopes, especially at anchor residues.
