RESUMO
Susceptibility of influenza A viruses to baloxavir can be affected by changes at amino acid residue 38 in the polymerase acidic (PA) protein. Information on replicative fitness of PA-I38-substituted viruses remains sparse. We demonstrated that substitutions I38L/M/S/T not only had a differential effect on baloxavir susceptibility (9- to 116-fold) but also on in vitro replicative fitness. Although I38L conferred undiminished growth, other substitutions led to mild attenuation. In a ferret model, control viruses outcompeted those carrying I38M or I38T substitutions, although their advantage was limited. These findings offer insights into the attributes of baloxavir-resistant viruses needed for informed risk assessment.
Assuntos
Antivirais/uso terapêutico , Farmacorresistência Viral/genética , Vírus da Influenza A Subtipo H1N1/genética , Vírus da Influenza A Subtipo H3N2/genética , Infecções por Orthomyxoviridae/tratamento farmacológico , Oxazinas/uso terapêutico , Piridinas/uso terapêutico , Tiepinas/uso terapêutico , Triazinas/uso terapêutico , Replicação Viral/genética , Substituição de Aminoácidos , Animais , Dibenzotiepinas , Modelos Animais de Doenças , Cães , Furões , Sequenciamento de Nucleotídeos em Larga Escala , Células Madin Darby de Rim Canino , Masculino , Testes de Sensibilidade Microbiana , Morfolinas , Infecções por Orthomyxoviridae/virologia , Piridonas , RNA Polimerase Dependente de RNA/genética , Estações do Ano , Resultado do Tratamento , Proteínas Virais/genéticaRESUMO
Baloxavir showed broad-spectrum in vitro replication inhibition of 4 types of influenza viruses (90% effective concentration range 1.2-98.3 nmol/L); susceptibility pattern was influenza A Ë B Ë C Ë D. This drug also inhibited influenza A viruses of avian and swine origin, including viruses that have pandemic potential and those resistant to neuraminidase inhibitors.
Assuntos
Antivirais/farmacologia , Gammainfluenzavirus/efeitos dos fármacos , Vírus da Influenza A/efeitos dos fármacos , Vírus da Influenza B/efeitos dos fármacos , Oxazinas/farmacologia , Piridinas/farmacologia , Tiepinas/farmacologia , Thogotovirus/efeitos dos fármacos , Triazinas/farmacologia , Animais , Galinhas/virologia , Dibenzotiepinas , Cães , Humanos , Influenza Aviária/tratamento farmacológico , Influenza Aviária/virologia , Influenza Humana/tratamento farmacológico , Influenza Humana/virologia , Células Madin Darby de Rim Canino/virologia , Testes de Sensibilidade Microbiana , Morfolinas , Infecções por Orthomyxoviridae/tratamento farmacológico , Infecções por Orthomyxoviridae/veterinária , Infecções por Orthomyxoviridae/virologia , Piridonas , Suínos/virologia , Doenças dos Suínos/tratamento farmacológico , Doenças dos Suínos/virologiaRESUMO
A total of 13672 viruses, collected by World Health Organization recognised National Influenza Centres between May 2016 and May 2017, were assessed for neuraminidase inhibitor susceptibility by four WHO Collaborating Centres for Reference and Research on Influenza and one WHO Collaborating Centre for the Surveillance Epidemiology and Control of Influenza. The 50% inhibitory concentration (IC50) was determined for oseltamivir and zanamivir for all viruses, and for peramivir and laninamivir in a subset (nâ¯=â¯8457). Of the viruses tested, 94% were obtained from the Western Pacific, Americas and European WHO regions, while limited viruses were available from the Eastern Mediterranean, African and South East Asian regions. Reduced inhibition (RI) by one or more neuraminidase inhibitor was exhibited by 0.2% of viruses tested (nâ¯=â¯32). The frequency of viruses with RI has remained low since this global analysis began (2015/16: 0.8%, 2014/15: 0.5%; 2013/14: 1.9%; 2012/13: 0.6%) but 2016/17 has the lowest frequency observed to date. Analysis of 13581 neuraminidase sequences retrieved from public databases, of which 5243 sequences were from viruses not included in the phenotypic analyses, identified 58 further viruses (29 without phenotypic analyses) with amino acid substitutions associated with RI by at least one neuraminidase inhibitor. Bringing the total proportion to 0.5% (90/18915). This 2016/17 analysis demonstrates that neuraminidase inhibitors remain suitable for treatment and prophylaxis of influenza virus infections, but continued monitoring is important. An expansion of surveillance testing is paramount since several novel influenza antivirals are in late stage clinical trials with some resistance already having been identified.
Assuntos
Antivirais/farmacologia , Farmacorresistência Viral , Inibidores Enzimáticos/farmacologia , Influenza Humana/virologia , Neuraminidase/antagonistas & inibidores , Orthomyxoviridae/efeitos dos fármacos , Substituição de Aminoácidos , Saúde Global , Humanos , Influenza Humana/epidemiologia , Concentração Inibidora 50 , Testes de Sensibilidade Microbiana , Mutação de Sentido Incorreto , Neuraminidase/genética , Orthomyxoviridae/enzimologia , Orthomyxoviridae/isolamento & purificação , Prevalência , Análise de Sequência de DNARESUMO
Extracted DNA from 28 Histomonas meleagridis -infected avian tissue samples from multiple hosts and geographic locations was analyzed for variation in the 5.8S rRNA and the flanking internal transcribed spacer regions (ITS 1 and ITS 2). Samples were amplified by polymerase chain reaction, sequenced, and compared with known sequences from GenBank accessions of H. meleagridis and other related protozoa. The analyses revealed significant genetic variation within H. meleagridis sequences and suggested the possibility of multiple genotypes within the samples or a possible misdiagnosis. Related protozoa found in some samples were mostly identified as Tetratrichomonas spp. However, 1 sample had a 93% identity to Simplicimonas similis , a newly described organism, suggesting the possibility of a new pathogen in poultry. A phylogenetic tree analyzing the 5.8S and flanking ITS regions was inconclusive and we were unable to resolve all H. meleagridis into a single grouping. In contrast, a tree constructed only on the 5.8S rRNA grouped all but 1 H. meleagridis sample into 1 clade, including GenBank accessions submitted from Europe. This suggests that the 5.8S region alone is more reliable in identifying H. meleagridis than are the combined 5.8S and flanking ITS regions. There was no correlation between genotypes and host species or geographic location, suggesting that H. meleagridis moves freely between multiple avian species in the sampled regions.
Assuntos
Doenças das Aves/parasitologia , Galliformes/parasitologia , Parabasalídeos/genética , Infecções Protozoárias em Animais/parasitologia , RNA Ribossômico/genética , Animais , DNA de Protozoário/genética , DNA Ribossômico/química , DNA Ribossômico/genética , DNA Espaçador Ribossômico/química , DNA Espaçador Ribossômico/genética , Variação Genética , Genótipo , Parabasalídeos/classificação , Filogenia , Reação em Cadeia da Polimerase/veterinária , RNA Ribossômico 5,8S/genética , Alinhamento de Sequência/veterinária , Estados UnidosRESUMO
Histomonas meleagridis , the causative agent of histomoniasis, is a protozoan parasite classified in the Dientamoebidae (order Tritrichomonadida). The α-tubulin gene of 7 H. meleagridis isolates originating from either domestic chickens or turkeys from the United States was amplified by nested PCR and sequenced. A 91.4-99.8% nucleotide identity was shared among the 7 different sequences, and phylogenetic analysis disclosed that the 7 isolates were divided into at least 3 clades. These sequences had a 91-99% nucleotide identity and a 96-100% amino acid identity compared with 3 H. meleagridis α-tubulin sequences obtained from isolates originating from turkeys in Germany. Further α-tubulin gene analysis from species in the Dientamoebidae will be useful in elucidating the evolutionary relationship of these protozoans.