Exploring the pathogenic and transmission characteristics of JN.1 in golden hamsters based on different attack methods.

Abstract

Since its emergence at the end of 2023, the JN.1 variant of COVID-19 has become the dominant strain globally. Currently, its characteristics in related animal models remain largely unknown. The results indicate that JN.1 can cause weight loss, viral load, viral titer, and histopathological changes in golden hamsters via intranasal and intragastric inoculation methods, with intranasal inoculation leading to faster viral replication. Interestingly, both viral load and viral titer of JN.1 are significantly lower than those of its parental strains BA.2 and XBB EG.5.1. A comparison of hematological data from the two inoculation methods was also consistent with previous findings. This highlights the importance of the infection route in studying the virus's progression and characteristics. In direct transmission studies of JN.1, the minimum time for virus transmission was 24 h, while XBB EG.5.1 could transmit the virus in as little as 6 h. Finally, the in vivo adaptability of JN.1 was investigated, with XBB EG.5.1 showing a more apparent adaptability advantage. Therefore, compared with EG.5.1, the pathogenicity and transmissibility of JN.1 are significantly weakened.