Immune characteristics distinguish patients with severe disease associated with SARS-CoV-2

This single-center, retrospective study aimed to explore the immune characteristics of COVID-19 and biomarkers to predict the severity of this disease. Patients infected with SARS-CoV-2 (n = 215) treated at the First Affiliated Hospital of Nanchang University from January 24 to March 12, 2020, were included in the study and classified into severe and non-severe groups. Peripheral immunocyte count and cytokine statuses were compared. The correlation between immune status, cytokine levels, and disease severity was analyzed. Leukocyte numbers were normal in both groups; however, they were relatively high (7.19 × 10⁹/L) in patients of the severe group. Leukocyte distributions differed between the two groups; the severe group had a higher percentage of neutrophils and lower percentage of lymphocytes compared with the non-severe group, and absolute lymphocyte numbers were below normal in both groups, and particularly deficient in patients in the severe group. Lymphocyte counts have negative correlation with duration of hospital period whereas neutrophil count has no significant correlation with it. Of tested cytokines, IL-6 levels were significantly higher in the severe group (P = 0.0418). Low level of lymphocyte predicts severity of COVID-19. IL-6 levels were significantly higher in the severe group, especially in some extremely severe patients. But we did not detect the significant correlation between severity of COVID-19 with IL-6 level which may be due to limited case numbers. Our observations encourage future research to understand the underlying molecular mechanisms and to improve treatment outcome of COVID-19.

Tick-Borne Pathogens in Ixodid Ticks from Poyang Lake Region, Southeastern China

Ticks are the vectors of various pathogens, threatening human health and animal production across the globe. Here, for the first time we detected Ricketssia spp., Borrelia spp. and protozoan in ticks from Poyang Lake region in Ji- angxi Province of eastern China. In 3 habitat categories and on 12 host species, 311 ticks from 11 species were collected. Haemaphysalis longicornis was the predominant species, accounting for 55.63%, followed by Rhipicephalus microplus, Haemaphysalis flava and Ixodes granulatus. Of the collected ticks, 7.07% were positive for tick-borne pathogens, and H. longicornis and H. flava were found to be co-infected with Ricketssia spp. and protozoan. H. flava was the most detected positive for tick-borne pathogens, whereas H. longicornis had the lowest infection rate, and the difference in infection rates between tick species was significant (χ2=61.24, P<0.001). Furthermore, adult ticks demonstrated remarkably greater infection rate than immature ticks (χ2=10.12, P=0.018), meanwhile ticks on Erinaceidae showed significantly higher positivity than ticks collected on other host species (χ2=108.44, P<0.001). Genetic fragment sequencing and analyses showed at least 4 pathogen species presence in ticks, namely Borrelia yangtzensis, Rickettsia slovaca or Rickettsia raoultii related genospecies, Babesia vogeli and Hepatozoon canis or Hepatozoon felis related genospecies. The finding indicates that the abundant ticks can carry diverse pathogens in Poyang Lake region, and pathogen infection is highly related to species, vertebrate hosts and life stages of ticks.