Influence of Different Inactivation Methods on Severe Acute Respiratory Syndrome Coronavirus 2 RNA Copy Number.

The outbreak of coronavirus disease 2019 (COVID-19) has spread across the world and was characterized as a pandemic. To protect medical laboratory personnel from infection, most laboratories inactivate the virus causing COVID-19, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), in clinical samples before testing. However, the effect of inactivation on the detection results remains unknown. Here, we used a digital PCR assay to determine the absolute SARS-CoV-2 RNA copy number in 63 nasopharyngeal swab samples and assess the effect of inactivation methods on viral RNA copy number. Viral inactivation was performed by three different methods: (i) incubation with the TRIzol LS reagent for 10 min at room temperature, (ii) heating in a water bath at 56°C for 30 min, and (iii) high-temperature treatment, including autoclaving at 121°C for 20 min, boiling at 100°C for 20 min, and heating at 80°C for 20 min. Compared to the amount of RNA in the original sample, TRIzol treatment destroyed 47.54% of the nucleocapsid protein (N) gene and 39.85% of open reading frame (ORF) 1ab. For samples treated at 56°C for 30 min, the copy number of the N gene and ORF 1ab was reduced by 48.55% and 56.40%, respectively. The viral RNA copy number dropped by 50 to 66% after heating at 80°C for 20 min. Nearly no viral RNA was detected after autoclaving at 121°C or boiling at 100°C for 20 min. These results indicate that inactivation reduced the quantity of detectable viral RNA and may cause false-negative results, especially in weakly positive cases. Thus, use of the TRIzol reagent rather than heat inactivation is recommended for sample inactivation, as the TRIzol reagent had the least effect on the RNA copy number among the tested methods.

Prevalence and protective factors of HIV and syphilis infection among men who have sex with men in Northwest China.

BACKGROUND: Men who have sex with men (MSM) continue to be disproportionately impacted by human immunodeficiency virus (HIV) and syphilis in China. Little is known about HIV and syphilis infections among MSM in Xi'an, a developing city in Northwest China. A cross-sectional study with recruitment via snowball sampling was conducted to collect HIV and syphilis infection status and risk factors among MSM in Xi'an between April 2013 to December 2016. Among the 5000 participants, the mean age was 29.0 years (SD 7.7) and the prevalence of HIV, syphilis, and coinfection was 6.5%, 2.2%, and 0.4%, respectively. There was no significant change in HIV prevalence from 2013 to 2016, while the prevalence of syphilis and coinfection showed a downward trend. Multiple logistic regression analyses found that being over 25 years old (OR = 1.647), junior high school/middle school education and below (OR = 3.085), with a sexual role of passive or versatile (OR = 3.300; OR = 2.337), rush poppers use during the last 6 months (OR = 1.660) and syphilis infection (OR = 2.235) were more likely to acquire HIV infection, whereas used condoms in the last episode of anal sex (OR = 0.572) and tested HIV antibody previously (OR = 0.252) were protective factors for HIV infection. HIV prevalence among MSM in Xi'an was stable, whereas the prevalence of syphilis and coinfection showed a downward trend. Interventions to promote HIV and sexually transmitted disease testing and condom use should be strengthened, especially for MSM with low education.

The characteristics of screening and confirmatory test results for HIV in Xi'an, China.

OBJECTIVES: Individuals with recent or acute HIV infection are more infectious than those with established infection. Our objective was to analyze the characteristics of detection among HIV infections in Xi'an. METHODS: A 4th-generation kit (Architect HIV Ag/Ab Combo) and three 3rd-generationEIA kits (WanTai, XinChuang and Livzon) were used for HIV screening. Overall, 665 individuals were identified as positive and were tested by western blotting (WB). The characteristics of the screening and confirmatory tests were analyzed, including the band patterns, the early detection performance and the false-positive rates. RESULTS: In total, 561 of the 665 patients were confirmed as having HIV-1 infection, and no HIV-2 specific band was observed. Among these 561 WB-positive cases, reactivity to greater than or equal to 9 antigens was the most commonly observed pattern (83.18%), and the absence of reactivity to p17, p31 and gp41 was detected in 6.44%, 5.9% and 2.86% of the cases, respectively. Two cases were positive by the 4th-generation assay but negative by the 3rd-generation assay for HIV screening and had seroconversion. The false-positive rate of the Architect HIV Ag/Ab Combo (22.01%) was significantly higher than those of WanTai (9.88%), XinChuang (10.87%) and Livzon (8.93%), p<0.05. CONCLUSION: HIV infection in Xi'an is mainly caused by HIV-1, and individuals are rarely identified at the early phase. Although the false-positive rate of the 4th-generation assay was higher than that of the 3rd-generation assay, it is still recommended for use as the initial HIV screening test for high-risk individuals. In Xi'an, a 3rd-generation assay for screening could be considered.

[Molecular epidemiology related to human immunodeficiency virus type 1 infection in men having sex with men in Xi'an].

OBJECTIVE: To investigate the subtype distribution of HIV-1 infection among men having sex with men (MSM) in Xi'an city. METHODS: 5 ml anti-coagulating blood samples were collected from MSM who had been reported during 2010-2012 in Xi'an. Both gag and env genes were amplified by nested RT-PCR from the extracted RNA and then sequenced. The acquired sequences were compared with international subtype references, and then the genetic distances were calculated and phylogenetic trees were constructed by Mega 5.2. Epidemiological information including sexual behavior characteristics, history of drug use, blood donation, etc. were gathered. RESULTS: 168 samples were successfully amplified and sequenced. Results from Phylogenic analysis showed that the gag and env sequences of 165 samples shared the same subtypes, of which 79 (47.0%) were CRF01_AE, 74 (44.0%) were CRF07_BC and 12 (7.1%) belonged to subtype B. There were 3 samples with gag and env sequences classified into different subtypes, of which 2(1.2%) were CRF01_AE/A1, and the other 1 was CRF07_BC/CRF01_AE. CONCLUSION: At least three HIV-1 subtypes including CRF01_AE, CRF07_BC were identified among MSM population in Xi'an city.