Pathogenicity and Interspecies Transmission of Cluster 3 Tembusu Virus Strain TMUV HQ-22 Isolated from Geese

Abstract

Since 2010, the Tembusu virus (TMUV) has been highly prevalent in China, causing significant economic losses to the poultry industry. In 2022, a suspected outbreak of TMUV occurred at a goose farm located in Anhui Province. A strain of TMUV, TMUV HQ-22, was isolated from the infected geese. Phylogenetic analysis using the E gene of the HQ-22 strain demonstrated its affiliation with cluster 3, a less commonly reported cluster in comparison to the main circulating cluster, cluster 2. Through a comparison of the envelope (E) protein of HQ-22 with other typical TMUV strains, a mutation at the 157th amino acid position was identified, wherein valine (V) in cluster 3 changed to alanine (A), a characteristic that is unique to cluster 2. These findings highlight the diversity and complexity of the TMUV strains circulating in China. In our experimental analysis, an injection of TMUV HQ-22 into the muscles of 3-day-old goslings resulted in severe neurological symptoms and a mortality rate of 60%. Similarly, the intracranial or intranasal infection of 3-week-old ICR mice with TMUV HQ-22 led to severe neurological symptoms and respective mortality rates of 100% or 10%. In summary, our study isolated a TMUV strain, TMUV HQ-22, from geese that belongs to cluster 3 and exhibits significant pathogenicity in both goslings and ICR mice. These results emphasize the genetic diversity of the TMUV circulating in China and expand the host range beyond mosquitoes to include ducks, chickens, geese, and even mice. It is crucial to not underestimate the risk of TMUV infection in mammals, warranting our utmost attention.

Advancements in Research on Duck Tembusu Virus Infections

“…While some DTMUV detection methods and vaccine formulations have been successfully launched in the domestic market, effectively curbing the spread and prevalence of certain strains, it is important to note that DTMUV belongs to the class of RNA viruses. RNA viruses have the propensity to mutate within the host environment, potentially leading to the ineffectiveness of existing detection methods and vaccines [11,15,30,147]. Additionally, with diverse transmission routes and a wide range of hosts, there is a potential risk of zoonotic transmission [11,15].…”

“…Since 2010, most strains isolated in Thailand and a small number from China belong to Cluster 2.a, while most isolates from China are assigned to Cluster 2.b. In recent years, two different research groups have identified a new cluster called Cluster 3 within the TMUV group, which collects virus isolates from China and Thailand [15,[30][31][32][33] (Figure 2).…”

“…Through the analysis of the full genome sequence of various DTMUV strains, it has been found that DTMUV exhibits high genetic diversity. Whether current inactivated and live attenuated vaccines provide immune protection against all strains is still unknown and requires further research [11,15].…”

“…Some studies have shown that DTMUV has a broad host range and various transmission routes, including vertical transmission [9] and mosquito-borne transmission [10], as well as direct contact and airborne transmission [11,12]. Besides infecting ducks, it can also infect chickens, geese, pigeons, and sparrows [13][14][15]. Literature reports have detected neutralizing antibodies against DTMUV in the serum of duck farm workers, although it has not been demonstrated to be pathogenic to humans, indicating potential zoonotic transmission between ducks and humans.…”

“…In 2022, the TMUV strain TMUV HQ-22 was isolated from infected geese in Anhui, China. Compared to other typical TMUV strains, it exhibited mutations in the envelope (E) protein and showed significant pathogenicity in goslings and ICR mice [15] (Figure 1).…”