ABSTRACT
In recent years, digital PCR (dPCR), as a novel nucleic acid amplification detection technique, contrasts real-time fluorescent quantitative PCR (qPCR) without the need to establish a standard curve, "single molecule template amplification" absolute quantification, insensitive to inhibitors that affect PCR efficiency, and excellent sensitivity, specificity, extremely strong repeatability and the development of the existing commercial platform technology that has great application advantages in virology and nucleic acid quantification. In this review, we address the application advantages of digital PCR in virus detection and describe its future development.
ABSTRACT
Objective To analyze the molecular epidemiology of adenovirus ( ADV) causing acute respiratory diseases and to investigate the mixed infection of ADV and other respiratory pathogens in Hebei Province. Methods Sputum samples were collected from inpatient children with acute respiratory diseases at Children′s Hospital of Hebei Province between June 2017 and May 2018. Multiplex reverse transcription PCR assay was used to detecte 13 kinds of respiratory pathogens. Nested PCR was performed to amplify ADV hexon gene and the amplified products were then sequenced. Results A total of 353 ADV-positive speci-mens were detected in 8839 specimens with a positive rate of 3. 99％. Significant difference in the positive rate of ADV was not observed between male and female patients (χ2=0. 0003, P=0. 99), but found among different age groups (χ2=115. 69, P<0. 001). All isolated ADV strains belonged to 11 serotypes, which were type 1 (16. 15％, 57/353), type 2 (35. 98％, 127/353), type 3 (21. 25％, 75/353), type 4 (1. 13％, 4/353), type 5 (11. 33％, 40/353), type 6 (3. 97％, 14/353), type 7 (8. 22％, 29/353), type 31 (0. 28％, 1/353), type 41 (0. 28％, 1/353), type 55 (0. 28％, 1/353) and type 57 (1. 13％, 4/353). Among the 353 ADV-positive specimens, 259 were mixed infections mainly caused by ADV and human rhinovirus (35. 52％). ADV and respiratory syncytial virus co-infections accounted for 12. 74％ and 33. 20％ of the mixed infections involved three or more pathogens. ADV could be detected throughout the year, especially in September and April to May. The predominant serotypes were types 1, 2 and 3. The av-erage ages of the two groups of ADV infection alone and ADV mixed infection were (27. 56±24. 67) months and (21. 33 ±20. 28) months, respectively, and the difference between them was statistically significant (P=0. 037). The incidence of ADV 2 infection alone was 25. 77％ (25/97), which was lower than that of ADV 2-involved mixed infection [39. 84％ (102/256),χ2=6. 05, P=0. 014]. However, the rate of ADV 7 infection alone was significantly higher than that of ADV 7-involved mixed infection [16. 49％ 16/97) vs 5. 08％ (13/256),χ2=6. 05, P<0. 001]. Conclusion ADV 1, ADV 2 and ADV 3 were the predominant serotypes circulating in Hebei Province from June 2017 to May 2018, especially in September and April to May. The younger the patients were, the higher the incidence would be. ADV 2 was prone to cause mixed infections with other respiratory pathogens, while ADV 7 was less common in mixed infections. Younger pa-tients were more susceptible to mixed infections. The most common co-infection was caused by ADV and hu-man rhinovirus.