Virome analysis of ticks in Zhoushan Archipelago, China.

Ticks are an important group of arthropod vectors. Ticks pose a profound risk to public health by transmitting many types of microorganisms that are human and animal pathogens. With the development of next-generation sequencing (NGS) technology and viral metagenomics, numerous novel viruses have been discovered in ticks and tick-related hosts. To fully understand the virus spectrum in ticks in the Zhoushan Archipelago of Zhejiang province in China, ticks were collected from Qushan Island, Zhoushan Island, and Daishan Island in the Zhoushan Archipelago in June 2016. NGS performed to investigate the diversity of tick-associated viruses identified 21 viral sequences. Twelve were pathogenic to humans and animals. Trough verification by polymerase chain reaction (PCR) revealed the existence of three tick-associated viruses with extensive homology with Dabieshan, MG22, and Odaw virus. Other NGS-detected sequences that could not be amplified by PCR were highly homologous (92-100%) with known pathogenic viruses that included hepatitis B virus, papillomavirus, and human mastadenovirus C. This is the first study to systematically apply high throughput sequencing technology to explore the spectrum of viruses carried by ticks in the Zhoushan Archipelago. The findings are fundamental knowledge of the diversity of tick-associated viruses in this region and will inform strategies to monitor and prevent the spread of tick-borne diseases.

Immunogenicity and safety of subunit plague vaccine: A randomized phase 2a clinical trial.

BACKGROUND: Although the killed whole-cell and live attenuated plague vaccine have been licensed, they are rarely used today because of toxicities, limited evidence of efficacy against plague, poor immune persistence required booster immunization every year, and limited commercial availability. This study was a randomized phase 2a clinical trial aimed to evaluating the immunogenicity and safety of a novel subunit plague vaccine. METHODS: 240 healthy adults aged 18-55 y were enrolled and randomly assigned at a ratio of 1:1 to receive 2 doses of 15 or 30 mcg vaccine at a 28-day interval between doses. Blood samples were collected at day 0, 28 and 56. Adverse events were collected during the first 28 d after each vaccination. Serious Adverse Event was observed throughout the study period. RESULTS: 239 participants received the first dose at day 0 and 238 received the second dose at day 28. Antibodies to envelope antigen faction 1 (F1) and recombinant virulence antigen (rV) were increased at day 28, and boosted significantly at day 56. For anti-F1 antibodies, geometric mean titer (GMT) and geometric mean fold increase (GMFI) were significantly higher in 30 mcg group than in the 15 mcg group(each P1< 0.05 at day 28 and each P1< 0.001 at day 56), with similar seroconversion rate of antibodies between 15 and 30 mcg group at both of the 2 time points. For anti-rV antibodies, seroconversion rate at day 28 in 30 mcg group was higher than that in 15 mcg group. However, GMT and GMFI of anti-rV antibodies were increased to approximately the same levels in the 2 groups. Similar booster immune response was also noticed in both groups at day 56. The injections were well tolerated, with mainly mild or moderate local and systemic adverse reactions (lower than grad 3). The proportion of pain at injection site was higher in 30 mcg group. None of SAEs were reported during 56 d. CONCLUSION: The plague vaccine comprised of F1 and rV antigens showed good safety and immunogenicity in adults aged 18-55 y old. The data show that the 30 mcg formulation is generally more immunogenic than the 15 mcg formulation, and represents the preferred formulation for further clinical development. It will be important to evaluate the long-term efficacy for appropriate formulations of the plague subunit vaccine.