Virological monitoring and analysis of polioviruses in Qinghai 2017 / 中华实验和临床病毒学杂志

Objective@#To evaluate 2017 poliovirus surveillance in Qinghai Province.@*Methods@#According to the World Health Organization (WHO) 4 th edition of the polio laboratory manual procedure for virus isolation, the isolated L20B positive strain was identified as intratypic differentiation (ITD) by the China Center for Disease Control and Prevention, CDC). The National Polio Laboratory performed the nucleotide sequence determination of the capsid protein VP1 coding region of poliovirus (PV) and analyzed the poliovirus surveillance and the result of analysis of the cases with acute flaccid paralysis (AFP) reported in Qinghai Province in 2017 and stool samples of healthy children.@*Results@#In 2017, Qinghai CDC Polio Laboratory received specimens of 211 AFP cases and healthy stool samples. PV2 strains were isolated with a separation rate of 0.95%. Non-polio enterovirus (NPEV) strains were isolated from 25 strains with the isolation rate of 11.85%. Two PVs were used for ITD. All of them were vaccine-associated strains.@*Conclusions@#In 2017, the Qinghai CDC Polio Laboratory did not find any poliovirus and vaccine-derived poliovirus in the AFP cases and stool samples from healthy persons, maintaining the polio-free status.

Genetic Characteristics of Coxsackievirus Group A Type 4 Isolated from Patients with Acute Flaccid Paralysis in Shaanxi, China / 病毒学报

We analyzed the genetic characteristics of coxsackievirus A4 (CV-A4) based on the entire VP1 coding region. Samples were isolated from patients with acute flaccid paralysis (AFP) in Shaanxi, China from 2006 to 2010. We wished to ascertain the predominant genotype and the relationship between CV-A4 infection and AFP. Sixty-eight non-polio enteroviruses were inoculated onto RD cells (to increase the virus titer) and molecular typing was undertaken. The entire VP1 coding region was amplified. Percentage of CV-A4 was 10.3% (7/68). Analyses of genetic identify and creation of phylogenetic trees revealed that CV-A4 could be classified into A, B and C genotypes. Seven CV-A4 strains from Shaanxi and other CV-A4 strains from China formed an independent evolution lineage located in group 4 and belonged to the C2 sub-genotype. These data suggested that CV-A4 strains of sub-genotype C2 were the predominant genotypes in China. These strains co-evolved and co-circulated with those from other provinces in China, so continued monitoring of CV-A4 (by clinical and genetic surveillance) should be enhanced.

Genetic Characteristics of Type 2 Vaccine-derived Poliovirus in Shanxi Province (China) in 2014 / 病毒学报

The World Health Organization redefined the type 2 vaccine-derived poliovirus (VDPV) in 2010. To study the genetic characteristics and evolution of type 2 VDPV under this new definition, we conducted genome sequencing and analyses of type 2 VDPVs isolated from one patient with acute flaccid paralysis in Shanxi province (China) in 2014. Nucleotide sequencing revealed that the full-length of type 2 VDPV is 7439 bases encoding 2207 amino acids with no insertion or deletion of nucleotides compared with Sabin2. One nucleotide substitution identified as a key determinant of the attenuated phenotype of the Sabin 2 strain (A-G reversion at nucleotide nt 481 in the 5-end of the untranslated region) had reverted in the Shanxi type 2 VDPV. The other known key determinant of the attenuated phenotype of the Sabin 2 strain (U-->C reversion at nt2909 in the VP1 coding region that caused a Ile143Thr substitution in VP1) had not reverted in the Shanxi VDPV. The Shanxi type 2 VDPV was S2/S1 recombinant, the crossover site of which mapped to the 3-end of the 3D region (between nt 6247 and nt 6281). A phylogentic tree based on the VP1 coding region showed that evolution of the Shanxi type 2 VDPV was independent of other type 2 VDPVs detected worldwide. We estimated that the strain circulated for approximately = 11 months in the population according to the known evolution rate. The present study confirmed that the Chinese Polio Laboratory Network could discover the VDPV promptly and that it played an important part in maintenance of a polio-free China.