Highly Pathogenic Avian Influenza A(H5N1) Virus Struck Migratory Birds in China in 2015

Abstract

Approximately 100 migratory birds, including whooper swans and pochards, were found dead in the Sanmenxia Reservoir Area of China during January 2015. The causative agent behind this outbreak was identified as H5N1 highly pathogenic avian influenza virus (HPAIV). Genetic and phylogenetic analyses revealed that this Sanmenxia H5N1 virus was a novel reassortant, possessing a Clade 2.3.2.1c HA gene and a H9N2-derived PB2 gene. Sanmenxia Clade 2.3.2.1c-like H5N1 viruses possess the closest genetic identity to A/Alberta/01/2014 (H5N1), which recently caused a fatal respiratory infection in Canada with signs of meningoencephalitis, a highly unusual symptom with influenza infections in humans. Furthermore, this virus was shown to be highly pathogenic to both birds and mammals, and demonstrate tropism for the nervous system. Due to the geographical location of Sanmenxia, these novel H5N1 viruses also have the potential to be imported to other regions through the migration of wild birds, similar to the H5N1 outbreak amongst migratory birds in Qinghai Lake during 2005. Therefore, further investigation and monitoring is required to prevent this novel reassortant virus from becoming a new threat to public health.

Highly pathogenic avian influenza H5N1 Clade 2.3.2.1c virus in migratory birds, 2014–2015

“…Additionally, other countries should also be on the alert for the potential introduction of this virus into their territories, as exemplified by the introduction of Clade 2.3.4.4 H5N1 viruses into North America and Europe during late 2014 (Jhung and Nelson, 2015;Verhagen et al, 2015). A successful example for outbreak control was the H5N1 outbreak amongst whooper swans in Sanmenxia during January 2015, in which high risk regions for virus transmission along the flyways (such as inner Mongolia) were alerted immediately (Bi et al, 2015a), which helped their preparations and in turn played a considerable role in controlling the outbreak. In addition, human infections with Clade 2.3.2.1c viruses constitute an important reminder of the public health risks from migratory birds carrying H5N1.…”

“…All of the sequences were aligned and phylogenetically analyzed. The HA phylogeny revealed that all of the novel sequences belonged to Clade 2.3.2.1c ( Figure 1) and were closely related to sequences isolated from Sanmenxia, China, where HPAI H5N1 viruses caused the deaths of approximately one hundred migratory birds (mostly whooper swans) between late 2014 and early 2015 (Bi et al, 2015a). Notably, the Chinese strains also clustered together with those from Russia, West Asia, Europe and Africa that were isolated during May 2015, winter of 2014 (Naguib et al, 2015), and spring of 2015 (Monne et al, 2015), respectively (Figure 1).…”

“…For the remaining seven genes, sequences from the strains mentioned above were clustered together and formed an independent sub-Clade (Figure 2 and Supplementary Figures S1-S6), indicating that they belonged to the same genotype. This genotype consisted of a Clade 2.3.2.1c HA (Figure 1) and a PB2 gene derived from H9N2 (Figure 2), with the remaining genes originating from other HPAI H5N1 viruses (Bi et al, 2015a;Monne et al, 2015). It should be noted that the prototype virus of this genotype (A/Alberta/01/2014) was first identified from a Canadian patient who traveled to Beijing, China in December 2013 (Pabbaraju et al, 2014).…”

“…H5N1 viruses are now considered endemic amongst domestic birds in China, Southeast Asia and Africa, and have evolved into numerous Clades and sub-Clades (World Health Organization, 2014). In particular, Clade 2.3.2.1 H5N1 viruses were identified for the first time from a dead Chinese pond heron in HKSAR during 2004, and circulated in wild birds during 2009~2011 (Hu et al, 2011;Sakoda et al, 2012 (WHO, 2014;Bi et al, 2015a).…”

“…During 2014-2015, a novel Clade 2.3.2.1c H5N1 virus caused several outbreaks amongst wild or domestic birds in Russia, China (Bi et al, 2015a), The United Arab Emirates (Western Asia) (Naguib et al, 2015), Bulgaria and Romania (Europe), and several African countries (FAO, 2015). In China, there have been at least three outbreaks in Sanmenxia Reservior, Inner Mongolia and Qinghai Lake, resulting in the deaths of thousands of wild birds.…”