Brazilian avian metapneumovirus subtypes A and B: experimental infection of broilers and evaluation of vaccine efficacy / Metapneumovirus aviário subtipos A e B brasileiros: infecção experimental em frangos de corte e eficácia vacinal

Avian metapneumovirus (aMPV) is a respiratory pathogen associated with the swollen head syndrome (SHS) in chickens. In Brazil, live aMPV vaccines are currently used, but subtypes A and, mainly subtype B (aMPV/A and aMPV/B) are still circulating. This study was conducted to characterize two Brazilian aMPV isolates (A and B subtypes) of chicken origin. A challenge trial to explore the replication ability of the Brazilian subtypes A and B in chickens was performed. Subsequently, virological protection provided from an aMPV/B vaccine against the same isolates was analyzed. Upon challenge experiment, it was shown by virus isolation and real time PCR that aMPV/B could be detected longer and in higher amounts than aMPV/A. For the protection study, 18 one-day-old chicks were vaccinated and challenged at 21 days of age. Using virus isolation and real time PCR, no aMPV/A was detected in the vaccinated chickens, whereas one vaccinated chicken challenged with the aMPV/B isolate was positive. The results showed that aMPV/B vaccine provided a complete heterologous virological protection, although homologous protection was not complete in one chicken. Although only one aMPV/B positive chicken was detected after homologous vaccination, replication in vaccinated animals might allow the emergence of escape mutants.

O Metapneumovírus aviário (aMPV) é um patógeno respiratório associado à síndrome da cabeça inchada (SHS) em galinhas. Apesar de vacinas vivas contra o aMPV serem utilizadas no Brasil, os subtipos A e B (aMPV/A e aMPV/B) são ainda encontrados no país, com predominância do subtipo B. Este estudo foi conduzido com o intuito de estudar dois isolados brasileiros de aMPV (subtipos A e B) isolados de frango. Para isto, um desafio experimental em frangos foi conduzido com o intuito de explorar a capacidade de replicação dos subtipos A e B Brasileiros. Posteriormente, a protecção virológica conferida por uma vacina do subtipo B em pintos foi realizada com os mesmos isolados. Após o desafio experimental demonstrou-se, por isolamento viral e PCR em tempo real, que o isolado do subtipo B replicou por maior período de tempo e em quantidades maiores, em comparação com o subtipo A. Para o estudo de proteção, 18 pintos de um dia de idade foram vacinados e desafiados aos 21 dias. Usando isolamento viral e PCR em tempo real, em nenhuma ave vacinada e desafiada com aMPV/A foi detectado o vírus, ao passo que uma ave vacinada e desafiada com o aMPV/B foi positiva. Os resultados mostraram que a vacina do subtipo B forneceu protecção heteróloga completa, embora a protecção homóloga não tenha sido conferida em uma ave. Apesar de o aMPV/B ter sido detectado em apenas um frango após vacinação homóloga, a replicação viral em aves vacinadas pode resultar em emergência de mutantes de escape.

Epidermal growth factor receptor and KRAS mutations in Brazilian lung cancer patients

OBJECTIVE: Epidermal growth factor receptor is involved in the pathogenesis of non-small cell lung cancer and has recently emerged as an important target for molecular therapeutics. The KRAS oncogene also plays an important role in the development of lung cancer. The aim of this study was to evaluate the frequency of epidermal growth factor receptor and KRAS mutations in a population of Brazilian patients with non-small cell lung cancer. METHODS: A total of 207 specimens from Brazilian patients with non-small cell lung cancer were analyzed for activating epidermal growth factor receptor and KRAS somatic mutations, and their associations with clinicopathological characteristics (including age, gender, ethnicity, smoking habits, and histological subtype) were examined. RESULTS: We identified 63 cases (30.4%) with epidermal growth factor receptor mutations and 30 cases (14.6%) with KRAS mutations. The most frequent epidermal growth factor receptor mutation we detected was a deletion in exon 19 (60.3%, 38 patients), followed by an L858R amino acid substitution in exon 21 (27%, 17 patients). The most common types of KRAS mutations were found in codon 12. There were no significant differences in epidermal growth factor receptor or KRAS mutations by gender or primary versus metastatic lung cancer. There was a higher prevalence of KRAS mutations in the non-Asian patients. Epidermal growth factor receptor mutations were more prevalent in adenocarcinomas than in non-adenocarcinoma histological types. Being a non-smoker was significantly associated with the prevalence of epidermal growth factor receptor mutations, but the prevalence of KRAS mutations was significantly associated with smoking. CONCLUSIONS: This study is the first to examine the prevalence of epidermal growth factor receptor and KRAS mutations in a Brazilian population sample with non-small cell lung cancer.