Genetic Characterization and Pathogenicity Analysis of Recently Isolated Fowl Adenovirus 8b in Korea.

A Korean field strain of fowl adenovirus (FAdV) 8b was isolated from chickens showing high mortality. Isolated FAdV-8b strains with the hexon and fiber genes were genetically analyzed. The Korean FAdV-8b (K194/19) strain isolated in 2019 showed higher sequence identity with the FAdV-8b strain isolated in China but lower sequence identity with the Korean FAdV-8b (K187/08) strain isolated in 2008. The K194/19 strain formed a distinct subcluster within the FAdV-8b cluster in a phylogenetic tree based on hexon and fiber genes. FAdV can infect day-old chicks through vertical transmission, and so blood samples were obtained from 54-, 60-, and 63-wk-old parent chickens. FAdV-specific antibody levels were investigated with ELISA and virus neutralization (VN) tests with the K194/19 and K187/08 strains as antigens. In VN tests, all sera neutralized the K187/08 strain. However, the K194/19 strain was neutralized by sera collected from 60- and 63-wk-old chickens but not sera obtained from 54-wk-old chickens, indicating natural infection. Finally, to determine the pathogenicity of the K194/19 strain, 1-day-old and 4-wk-old specific-pathogen-free birds were infected with the K194/19 and K187/08 strains. No significant difference in pathogenicity was observed between the two strains. Although the K194/19 strain showed similar pathogenicity with the K187/08 strain, differences in nucleotide and amino acid sequences of the hexon and fiber genes may determine the evasion ability of the K187/08 neutralizing antibody, indicating the need for development of a novel FAdV vaccine.

Nota de investigación­Caracterización genética y análisis de patogenicidad de un adenovirus del pollo 8b aislado recientemente en Corea. Se aisló una cepa de campo coreana de adenovirus del pollo (FAdV) 8b de aves que mostraban una alta mortalidad. Se analizaron genéticamente cepas de FAdV-8b aisladas mediante los genes de hexón y de la fibra. La cepa coreana FAdV-8b (K194/19) aislada en 2019 mostró una mayor identidad de secuencia con la cepa FAdV-8b aislada en China, pero una menor identidad de secuencia con la cepa coreana FAdV-8b (K187/08) aislada en 2008. La cepa K194/19 formó un subgrupo distinto dentro del grupo de adenovirus del pollo 8b en un árbol filogenético basado en los genes de las fibras y hexones. El FAdV puede infectar a pollitos de un día a través de la transmisión vertical, por lo que se obtuvieron muestras de sangre de pollos reproductores de 54, 60 y 63 semanas de edad. Los niveles de anticuerpos específicos de FAdV se investigaron con ELISA y pruebas de neutralización de virus (VN) con las cepas K194/19 y K187/08 como antígenos. En las pruebas de neutralización, todos los sueros neutralizaron a la cepa K187/08. Sin embargo, la cepa K194/19 fue neutralizada por sueros recolectados de pollos de 60 y 63 semanas de edad, pero no por los sueros obtenidos de pollos de 54 semanas de edad, lo que indica una infección natural. Finalmente, para determinar la patogenicidad de la cepa K194/19, se infectaron aves libres de patógenos específicos de un día y cuatro semanas de edad con las cepas K194/19 y K187/08. No se observaron diferencias significativas en la patogenicidad entre las dos cepas. Aunque la cepa K194/19 mostró una patogenicidad similar con la cepa K187/08, las diferencias en las secuencias de nucleótidos y aminoácidos de los genes del hexón y de la fibra pueden determinar la capacidad para evadir los anticuerpos neutralizantes K187/08, lo que indica la necesidad de desarrollar una nueva vacuna contra adenovirus del pollo.

Efficacy of a novel avian metapneumovirus live vaccine candidate based on vaccination route and age.

This article describes a series of animal studies for the development of an avian metapneumovirus (aMPV) live vaccine. Although aMPV causes continual economic loss in the poultry industry, there are no live aMPV vaccines available in Korea. Furthermore, information is limited with respect to standard field practices for vaccinations at an early age. Here, the development of an aMPV live vaccine was attempted, and its efficacy was investigated with respect to the vaccination route and age to develop a method for controlling aMPV. Before vaccine development, an animal challenge model was established using the aMPV field isolate to identify the most effective time and site for collecting samples for evaluation. After attenuation of the virulent aMPV in Vero cells, a safety and efficacy test was conducted for the vaccine candidate. As a novel aMPV live vaccine candidate, aMPV K655/07HP displayed sufficient safety in day-old chicks with 10 vaccine doses. The efficacy test using 1-week-old chicks showed weaker humoral immune response than that in 4-week-old chicks. However, the candidate vaccine provided complete protection against infection caused by the challenge virus for all ages of vaccinated chicks. In conclusion, an effective aMPV challenge model was established for studying aMPV in chickens, which offered important, insightful information. The safety and efficacy study suggested that the new aMPV candidate vaccine could be used to effectively reduce the economic losses incurred because of aMPV infection.

Potential use of 3-(trimethoxysilyl)propyldimethyl octadecyl ammonium chloride as an antimicrobial and antiviral agent for the disinfection of personal protective equipment.

Currently, no vaccine or established therapeutic agents are available for coronavirus disease 2019. The sharp increase in demand for personal protective equipment (PPE) necessitates an improvement in the protective efficacy of PPE. We evaluated the potential antimicrobial and antiviral effects of a surface-coating disinfectant (3-(trimethoxysilyl)propyldimethyl octadecyl ammonium chloride, Si-QAC) when applied onto PPE. Si-QAC-pre-coated PPE was artificially contaminated with either influenza virus or Salmonella. The results showed significantly reduced influenza and Salmonella titers in Si-QAC-coated PPE; these antimicrobial effects lasted 7 days. This suggests that this surface-coating disinfectant effectively reduces pathogen contamination of PPE, enabling their safe and long-term use.