Emergence of the H208Y mutation in the reverse transcriptase (RT) of HIV-1 in association with nucleoside RT inhibitor therapy

OBJECTIVES: The aim of the study was to determine whether mutations at RT codon 208 are associated with nucleoside RT inhibitor (NRTI) exposure, NRTI resistance patterns and HIV-1 subtype. METHODS: Six thousand three hundred and fifty two genotypic resistance tests linked to a clinical database were analysed. RESULTS: The prevalence of mutations at codon 208 was 6/2347 (0.3%) in treatment-naive and 165/4005 (4.1%) in treatment-experienced persons. H208Y was the most common mutation in both groups (0.2% and 3.8%, respectively) and occurred in 4.5% of treatment-experienced persons with Subtype B, 1.7% of those with Subtype C and 0.7% of those with other non-B subtypes (P=0.001). The association with subtypes was independent of treatment experience. H208Y showed a strong association with NRTI experience, which persisted after adjusting for subtype [odds ratio (OR) 19.34; 95% confidence interval (CI) 7.87-47.54; P=0.0001]. The prevalence of H208Y was highest in genotypes harbouring M184V and the thymidine analogue mutations (TAMs) M41L, D67N, L210W and T215Y. The median number of TAMs was 4 and 0 in genotypes with and without H208Y, respectively (P=0.0001). The prevalence of H208Y declined over time, being highest in 1998 (9.9%) and lowest in 2003 (0.9%) (P=0.0001). CONCLUSIONS: There is a strong association between H208Y and NRTI experience, particularly in persons with Subtype B harbouring multiple NRTI resistance mutations. These findings indicate an accessory role for H208Y in NRTI resistance.     

2006-2007年辽宁省儿童流行性感冒病原学检测分析

目的　分析辽宁省2006-2007年度流行性感冒（流感）的病原学及流行特征。方法　在流行季节采集咽拭子用鸡胚和细胞分离方法，进行间接血凝抑制试验。结果　共采集儿童标本213份，分离流感毒株41株，分离率为19.25%；其中A型31株（H1亚型14株、H3亚型17株），B型10株，流感的高发年龄主要集中在4～9岁之间。结论　2006-2007年辽宁省内同时有三种亚型的流感病毒在流行，2006年底前优势株是H1亚型，2007年优势株转为H3亚型和B亚型。     

Variant human immunodeficiency virus type 1 proteases and response to combination therapy including a protease inhibitor

The objective of this observational study was to assess the genetic variability in the human immunodeficiency virus (HIV) protease gene from HIV type 1 (HIV-1)-positive (clade B), protease inhibitor-na?ve patients and to evaluate its association with the subsequent effectiveness of a protease inhibitor-containing triple-drug regimen. The protease gene was sequenced from plasma-derived virus from 116 protease inhibitor-na?ve patients. The virological response to a triple-drug regimen containing indinavir, ritonavir, or saquinavir was evaluated every 3 months for as long as 2 years (n = 40). A total of 36 different amino acid substitutions compared to the reference sequence (HIV-1 HXB2) were detected. No substitutions at the active site similar to the primary resistance mutations were found. The most frequent substitutions (prevalence, >10%) at baseline were located at codons 15, 13, 12, 62, 36, 64, 41, 35, 3, 93, 77, 63, and 37 (in ascending order of frequency). The mean number of polymorphisms was 4.2. A relatively poorer response to therapy was associated with a high number of baseline polymorphisms and, to a lesser extent, with the presence of I93L at baseline in comparison with the wild-type virus. A71V/T was slightly associated with a poorer response to first-line ritonavir-based therapy. In summary, within clade B viruses, protease gene natural polymorphisms are common. There is evidence suggesting that treatment response is associated with this genetic background, but most of the specific contributors could not be firmly identified. I93L, occurring in about 30% of untreated patients, may play a role, as A71V/T possibly does in ritonavir-treated patients.     

Neuraminidase inhibitor susceptibility profile of human influenza viruses during the 2016–2017 influenza season in Mainland China

To understand the current situation of antiviral-resistance of influenza viruses to neuraminidase inhibitors (NAIs) in Mainland China, The antiviral-resistant surveillance data of the circulating influenza viruses in Mainland China during the 2016–2017 influenza season were analyzed.The total 3215 influenza viruses were studied to determine 50% inhibitory concentration (IC₅₀) for oseltamivir and zanamivir using a fluorescence-based assay.Approximately 0.3% (n = 10) of viruses showed either highly reduced inhibition (HRI) or reduced inhibition (RI) against at least one NAI. The most common neuraminidase (NA) amino acid substitution was H275Y in A (H1N1)pdm09 virus, which confers HRI by oseltamivir. Two A (H1N1)pdm09 viruses contained a new NA amino acid substitution respectively, S110F and D151E, which confers RI by oseltamivir or/and zanamivir. Two B/Victoria-lineage viruses harbored a new NA amino acid substitution respectively, H134Q and S246P, which confers RI by zanamivir. One B/Victoria-lineage virus contained dual amino acid substitution NA P124T and V422I, which confers HRI by zanamivir. One B/Yamagata-lineage virus was a reassortant virus that haemagglutinin (HA) from B/Yamagata-lineage virus and NA from B/Victoria-lineage virus, defined as B/Yamagata-lineage virus confers RI by oseltamivir, but as B/Victoria-lineage virus confers normal inhibition by oseltamivir. All new substitutions that have not been reported before, the correlation of these substitutions and observed changes in IC₅₀ should be further assessed.During the 2016–2017 influenza season in Mainland China the majority tested viruses were susceptible to oseltamivir and zanamivir. Hence, NAIs remain the recommended antiviral for treatment and prophylaxis of influenza virus infections.     

In vitro expression of human hepatitis B virus genomes carrying woodchuck hepatitis virus pre-S1 sequences

Many hepatitis B virus (HBV) in vivo experiments are unfeasible because this virus infects only humans. Former studies demonstrated that the pre-S1 domain of the viral envelope protein L determines host range. Therefore, we tried to generate HBV recombinants which might be able to infect woodchucks by exchanging different portions of the pre-S1 encoding gene with homologous parts from the related woodchuck hepatitis virus (WHV) in a cloned HBV genome. In 6 mutants, 11-92 N-terminal HBV pre-S1 codons were replaced by 20-120 codons from WHV. Four mutants carried C-terminal substitutions. The pre-S1 region overlaps with the viral polymerase gene, which is therefore also affected. After transfection of Huh7 cells, the DNA polymerase activity in cytoplasmic nucleocapsids was found to be only slightly affected. All mutants except for the largest C-terminal substitution allowed virion formation. Only the smallest N- and C-terminal substitutions had a wild-type phenotype. The remaining 7 variants allowed virion yields between 5 and 50% of that of the wild type. This demonstrated that substitution of up to 92 pre-S1 codons in an HBV genome with up to 120 codons from WHV pre- S1 was compatible with DNA replication and virion formation. Some recombinant viruses might be able to grow in woodchucks.     

Antigenic drift in influenza A viruses. I. Selection and characterization of antigenic variants of A/PR/8/34 [HON1] influenza virus with monoclonal antibodies

Antigenic variants of A/PR/8/34 [HON1] influenza virus were selected after a single passage of the parent virus in embryonated chicken eggs in the presence of monoclonal antibodies to this virus. The monoclonal antibodies were produced by a hybridoma and were specific for an antigenic determinant on the HA molecule of the parent virus. Seven antigenic variants were analyzed with 95 monoclonal anti-HA antibodies prepared in vitro in the splenic fragment culture system. Three subgroups of antigenic variants were distinguished. The antigenic changes were primarily recognized by monoclonal antibodies to the strain- specific determinants of the parental hemagglutinin (HA) molecule. Monoclonal antibodies to HA determinants shared (in an identical or cross-reactive form) by parental virus and more than three heterologous viruses of the HON1 and H1N1 subtypes were unable to recognize the antigenic change on the variants. Similarly, heterogeneous antibody preparations could not differentiate between parental and variant viruses. The results are compatible with the idea that the HA of PR8 has available a large repertoire of antigenic modifications that may result from single amino acid substitutions, and that antigenic changes can occur in the strain- specific determinants on the HA molecule in the absence of concomitant changes in the cross-reactive HA determinants. The findings suggest that antigenic drift, in order to be epidemiologically significant, probably requires a series of amino acid substitutions in, or close to, the antigenic area on the HA molecule.     

In vitro hypersusceptibility of human immunodeficiency virus type 1 subtype C protease to lopinavir

In order to characterize the impact of genetic polymorphisms on the susceptibility of subtype C strains of human immunodeficiency virus type 1 to protease inhibitors (PIs), a subtype B protease that originated from an infectious clone was modified through site-directed mutagenesis to include the amino acid residue signatures of subtype C viruses (I15V, M36I, R41K, H69K, L89 M) with (clone C6) or without (clone C5) an I93L polymorphism present as a molecular signature of the worldwide subtype C protease. Their susceptibilities to commercially available PIs were measured by a recombinant virus phenotyping assay. We could not detect any differences in the 50% inhibitory concentration (IC(50)s) of amprenavir, indinavir, ritonavir, saquinavir, and nelfinavir for the clones analyzed. However, we did observe hypersusceptibility to lopinavir solely in clone C6, which includes the I93L substitution (a 2.6-fold decrease in the IC(50) compared to that for the subtype B reference strain). The same phenotypic behavior was observed for 11 Brazilian and South African clinical isolates tested, in which only subtype C isolates carrying the I93L mutation presented significant hypersusceptibility to lopinavir.     

HER2‐Positive Endometrial Cancer Subtype Carries Poor Prognosis

Endometrial cancer (EC) is a hormone‐dependent, most frequent malignancy of the female genital tract, yet no molecular subtype classification based receptor status (estrogen receptor [ER], progesterone receptor [PR], human epidermal growth factor receptor 2 [HER2]) has been established so far. Assuming that molecular subtypes might differ fundamentally in EC, we analyzed expression levels of ER, PR, and HER2 with immunohistochemistry and aimed to determine clinical significance of four molecular subtypes: ER+/PR+/HER2+; ER+/PR+/HER2−, ER−/PR−/HER2+, and ER−/PR−/HER2−. The study included 400 formalin‐fixed paraffin‐embedded primary tumor EC samples which covered all stages of endometrial carcinoma, from IA to IVB. ER−/PR−/HER2+ subtype correlated with the poorest outcome, ER+/PR+/HER2− subtype was associated with the most favorable prognosis (p = 0.002). Molecular subtype division remained an independent prognostic factor in multivariate analysis, accompanying parameters such as diabetes, hypertension, stage, myometrial infiltration, and metastases, all of which yielded hazard ratios between 1.39 and 2.23. ER+/PR+/HER2+ and ER+/PR+/HER2− subtypes had low average TP53 and TOP2A expression levels when compared with ER−/PR−/HER2+ and ER−/PR−/HER2− (both p < 0.00001). Molecular subtypes in EC do show diversity in terms of prognosis, clinicopathological, and molecular characteristics. ER−/PR−/HER2+ subtype exhibit is exceptionally aggressive tumor characteristics. Subtype differentiation might aid prediction of treatment response in EC.