Prevalence of serum neutralizing antibodies to adenovirus type 5 (Ad5) and 41 (Ad41) in children is associated with age and sanitary conditions.

Neutralizing antibody (NAb) can dampen the immunogenicity of adenovirus (Ad) vector-based vaccine. Vector systems based on human adenovirus type 41 (Ad41) have been constructed and used to develop recombinant vaccines. Here, we attempted to study the seroprevalence of NAbs to Ad5 and Ad41 among children and adults in Qinghai province, China. The positive rates (titer⩾40) of Ad5 and Ad41 NAb in adults from Xining city were 75.7% and 94.7%, respectively. The moderate/high-positive rates (titer⩾160) of NAb were quite close between the two viruses in adults (70.4% for Ad5 and 73.5% for Ad41). Age-dependent increase of NAb seroprevalence was observed for both viruses in children. NAb-positive rate of Ad41 reached 50% at 3.3-4.6years of age for children from Chengxi district, Xining city, approximately 1.5years earlier than that of Ad5 did. Interestingly, NAb level was also associated with sanitary conditions among young children. For Ad5, 8-15% children (0.2-3.0years of age) from city or town, where the sanitations were relatively better, had moderate/high-positive NAb, while the same rate was 62% for children from villages. For Ad41, 22% children from city, 47% from town and 88% from villages possessed moderate/high-positive NAb. The possible influence of NAb titer distributions on the application of Ad41-vectored vaccines was discussed in detail. Our results suggested that children from places with poor sanitations should be included for comprehensive Ad NAb seroprevalence studies, and provided insights to the applications of Ad41 vectors.

[Complete genome phylogenetic analysis of five H9N2 avian influenza viruses isolated from poultry flocks in Qinghai lake region].

Five H9N2 avian influenza virus strains were isolated from the environmental samples in live poultry market in Qinghai Lake region from July to September, 2012. To evaluate the phylogenetic characteristics of these H9N2 isolates, the eight gene segments were amplified by RT-PCR and sequenced. The phylogenetic and molecular characteristics of the five strains were analyzed. The results showed that the HA genes of five strains shared 93. 2%-99. 1% nucleotide identities with each other, and the NA genes shared 94. 5%-99. 8% nucleotide identities. The HA cleavage site sequence of the A/environment/qinghai/ 017/2012 isolate was PSKSSRGLF, and the HA cleavage site sequences of the other four strains were all PSRSSRGLF. The HA receptor-binding site had the Q226L mutation. The M1 gene segment had the N30D and T215A mutations. The phylogenetic analysis showed that the five strains were similar to the virus A/chicken/Hunan/5260/2005 (H9N2) isolated in Hunan Province, China and were reassortant genotype viruses; the HA, NA, and NS genes belonged to the Y280-like lineage; the MP gene belonged to the G1-like lineage; the NP, PB1, PB2, and PA genes belonged to the F98-like lineage.

[Molecular epidemiological study of measles viruses isolated in Qinghai Province during 2000-2011].

OBJECTIVE: To carry out the molecular epidemiological study of the wild-type measles virus isolated in Qinghai Province during 2000-2011, and provide a scientific basis for the measles elimination. METHODS: Measles viruses were isolated using B95a cell line or Vero/SLAM cell line from throat swabs collected from suspected measles cases during measles outbreak and sporadic in 6 prefectures during 2000-2011. The fragment of 696 nucleotides of N gene carboxy terminal was amplified by using RT-PCR methods. The PCR products were sequenced and analyzed. The phylogenetic tree was conducted with the viruses isolated in viruses from other province. RESULTS: Total 19 measles viruses were isolated during 2000-2011 in Qinghai province and all belong to genotype H1a. The results of phylogenetic tree showed that viruses in 2000-2005 and in 2009-2011 were distributed in two different lineages, and it revealed that these strains belonged to at least 2 viral transmission chains and the viruses circulated during 2000-2005 were not detected after 2005. CONCLUSION: Genotype H1a was the predominant genotype circulated in Qinghai province during 2000-2011. Qinghai measles virus strains had not evolved independently, but coevolved with the measles virus strains in other provinces in mainland China. The variation of important amino acid sites of measles virus should be continuous monitored and provide the scientific strategy for the measles elimination.

[Human enterovirus 71 that firstly isolated in Qinghai Province and their genetic features of VP1 region].

OBJECTIVE: To study the genetic characterizations of VP1 gene of human enterovirus 71 (HEV71) isolated from clinical specimens of Hand, Foot and Mouth Disease (HFMD) patients in Qinghai Province in 2008. METHODS: 335 clinical samples including stools, throat swabs and vesicle fluids were collected from HFMD patients in Qinghai Province. Viral isolation was performed, and molecular typing was performed with the positive isolates. Then 30 identified HEV71 isolates were performed for entire VP1 coding region amplification and sequencing. RESULTS: Among the 355 clinical samples, 45 human enteroviruses were isolated, and among them, 30 were identified as HEV71. Then 30 HEV71 positive isolates were performed by nucleotide sequencing. It showed that there was some difference in the nucleotide and the amino acid among the 30 HEV71 strains, the homology were 95.2%-100% and 96.6%-100%, respectively. But they all closed to HEV71 strains isolated in China after 1998, and from the phylogenetic tree constructed with 30 Qinghai HEV71 strains and other 35 HEV71 strains represented all known genotype and subgenotype HEV71 strains available from GenBank, it revealed that the 30 Qinghai HEV71 strains clustered within the C4a evolution branch of C4 subgenotype. CONCLUSION: HEV71 was isolated in HFMD patients in Qinghai province, and the HEV71 strains causing HFMD outbreaks in Qinghai province in 2008 were all belong to C4a evolution branch of C4 subgenotype with several transmission chains.

Mosquitoes and mosquito-borne arboviruses in the Qinghai-Tibet Plateau--focused on the Qinghai area, China.

An investigation was conducted to identify the distribution of mosquitoes and mosquito-borne arboviruses in the Qinghai-Tibet Plateau, China from July to August in 2007. A total of 8,147 mosquitoes representing six species from three genera (Aedes, Culex, and Anopheles) were collected in three locations (Geermu city, altitude of 2,780 m; Xining city, 2,200 m; Minhe county, 1,700 m). Six virus isolates were obtained including Tahyna virus (TAHV), Liaoning virus, and Culex pipiens pallens Densovirus. A serosurvey showed immunoglobulin G antibodies by immunofluorescence assay (IFA) against TAHV in residents of all three locations. The IFA-positive human samples were confirmed by 90% plaque-reduction neutralization tests (PRNT(90)) against TAHV with titers ranging from 1:20 to 1:10,240. In addition, TAHV seropositive cows, sheep, and swine were found in these locations. This investigation represents the first isolation of TAHV from Ae. (Och.) detritus and the first evidence of TAHV infection in residents and livestock in the Qinghai-Tibet Plateau.

[Investigation on distribution of HBV genotype and serotype from Tibetan in Tongde, Qinghai].

OBJECTIVE: To explore the distribution of HBV genotype and serotype from Tibetan in Tongde, Qinghai. METHODS: Nested polymerase chain reaction (nPCR) was used for amplification of S gene and C gene of HBV from sera carried by Tibetan chronic HBV carrier in Tongde, Qinghai, then the HBV DNA positive products were sequenced by direct sequencing. Genotype and serotype were identified by analysis of sequence result. RESULTS: 271, which come from 311 sera samples with positive HBsAg randomly selected from natural community, were amplified and sequenced in both S gene and C gene successfully, 10 (3.7%), 261 (96.3%) out of them were identified as genotype C, recombinant between genotypes C and D respectively; 259 (95.6%), 10 (3.7%), 2 (0.7%) belonged to serotype ayw2, adr, adw2 respectively. CONCLUSION: The recombinant between genotypes C and D was the main genotype in Tibetan chronic carrier with hepatitis Bin Tongde, Qinghai; the serotype of this areas was consisted largely of ayw2.