We compared the epidemiological and clinical features of avian influenza A(H7N9) virus infections in the population in Zhejiang province, China, between March and April 2013 (first wave) and October 2013 and February 2014 (second wave). No statistical difference was found for age, sex, occupation, presence of underlying conditions, exposure history, white blood cell count, lymphocyte percentage and illness timeline and duration (all P > 0.05). The virus spread to 30 new counties compared to the first wave. The case-fatality rate was 22% in the first wave and 42% in the second (P = 0.023). Of those infected, 66% in the first wave and 62% in the second wave had underlying conditions. The proportion of those exposed to live poultry markets were 80% and 66%, respectively. We recommend permanent closure of live poultry markets and reformation of poultry supply and sales.

SUMMARYSevere fever with thrombocytopenia syndrome virus (SFTSV) has been prevalent for some time in China and it was first identified in 2010. However, the seroprevalence of SFTSV in the general population in southeastern China and risk factors associated with the infection are currently unclear. Blood samples were collected from seven counties across Zhejiang province and tested for the presence of SFTSV-specific IgG antibodies by ELISA. A total of 1380 blood samples were collected of which 5·51% were seropositive for SFTSV with seroprevalence varying significantly between sites. Seroprevalence of SFTSV in people who were family members of the patient, lived in the same village as the patient, or lived in a different village than the patient varied significantly. There was significant difference in seroprevalence between participants who bred domestic animals and participants who did not. Domestic animals are probably potential reservoir hosts and contact with domestic animals may be a transmission route of SFTSV.

Mixed infection by plant viruses is common in nature, but how a key viral protein of one virus affects the infection by heterologous viruses is not yet fully understood. The helper component proteinase (HCPro) is a widely studied RNA silencing suppressor encoded by viruses of the family Potyviridae. Here, we investigated the defence response of Nicotiana tabacum plants overexpressing HCPro of chilli veinal mottle virus (HCPro‐OX) to tobacco mosaic virus and cucumber mosaic virus infection. We monitored the physiological and molecular changes of HCPro‐OX plants in response to virus infection. The results showed that HCPro‐OX plants under virus infection exhibited higher susceptibility at the early stage but stronger tolerance at the later stage compared to wild‐type plants. The tolerance to heterologous virus infection of HCPro‐OX plants corresponded to a lower level of reactive oxygen species accumulation and higher activities of several antioxidant enzymes. Reverse transcription‐quantitative PCR assays showed that the expression of genes related to salicylic acid (SA) pathways was significantly upregulated, but the expression of genes related to the auxin pathways was downregulated at the late stage of virus infection in HCPro‐OX plants compared to wild‐type plants. By contrast, the situation in the early stage of virus infection was reversed. In addition, pretreatment with SA, the auxin naphthylacetic acid (NAA) and their respective inhibitors 1‐aminobenzotriazole (ABT) and naphthalam (NPA) further confirmed the antagonistic effects of SA and NAA in the response of HCPro‐OX plants to heterologous virus infection. Thus, our results demonstrate that HCPro affects heterologous virus infection through SA and auxin pathways.

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