Phylogenetic Inference of the 2022 Highly Pathogenic H7N3 Avian Influenza Outbreak in Northern Mexico

Roberto Navarro-Lopez; Wanhong Xu; Ninnet Gomez-Romero; Lauro Velazquez-Salinas; Yohannes Berhane

doi:10.3390/pathogens11111284

Phylogenetic Inference of the 2022 Highly Pathogenic H7N3 Avian Influenza Outbreak in Northern Mexico

Pathogens. 2022 Nov 1;11(11):1284. doi: 10.3390/pathogens11111284.

Authors

Roberto Navarro-Lopez¹, Wanhong Xu², Ninnet Gomez-Romero¹, Lauro Velazquez-Salinas³, Yohannes Berhane^{2

4}

Affiliations

¹ United States-Mexico Commission for the Prevention of Foot-and-Mouth Disease and Other Exotic Disease Animals, Mexico City 64590, Mexico.
² National Centre for Foreign Animal Disease, Winnipeg, MB R3E 3M4, Canada.
³ Plum Island Animal Disease Center, Agriculture Research Service, USDA, Orient, NY 11944, USA.
⁴ Department of Animal Science, University of Manitoba, Winnipeg, MB R3T 2S2, Canada.

Abstract

The Mexican lineage H7N3 highly pathogenic avian influenza virus (HPAIV) has persisted in Mexican poultry since its first isolation in 2012. To date, the detection of this virus has gradually expanded from the initial one state to 18 states in Mexico. Despite the HPAIV H7N3 outbreak occurring yearly, the transmission pathways have never been studied, disallowing the establishment of effective control measures. We used a phylogenetic approach to unravel the transmission pathways of 2022 H7N3 HPAIVs in the new outbreak areas in Northern Mexico. We present genetic data of H7N3 viruses produced from 18 poultry farms infected in the spring of 2022. Our results indicate that the virus responsible for the current outbreak in Northern Mexico evolved from the Mexican lineage H7N3 HPAIV discovered in 2012. In the current outbreak, we identified five clusters of infection with four noticeably different genetic backgrounds. It is a cluster IV-like virus that was transmitted into one northern state causing an outbreak, then spreading to another neighboring northern state, possibly via a human-mediated mechanical transmission mechanism. The long-distance transmission event highlights the necessity for the more rigorous enforcement of biosafety measures in outbreaks. Additionally, we examined the evolutionary processes shaping the viral genetic and antigenic diversities. It is imperative to enhance active surveillance to include birds, the environment, and humans to detect HPAI in domestic poultry at an earlier point and eliminate it.

Keywords: H7N3; antigenic evolution; avian influenza virus; genetic diversity; highly pathogenic; phylogenetic analysis; transmission network.

Grants and funding

This work was supported by the Canadian Food Inspection Agency (Project C00454) and Mexican Animal Health General Directorate, Animal and Plant Health, Food Inspection and Food Safety National Services (SENASICA), Secretariat of Agriculture, Livestock, Rural Development, Fisheries and Food (SAGARPA)—Internal funding, no project number.