[Analysis of Tat protein characteristics in human immunodeficiency virus type 1 sub-subtype A6 (Retroviridae: Orthoretrovirinae: Lentivirus: Human immunodeficiency virus-1)].

INTRODUCTION: Tat protein is a major factor of HIV (human immunodeficiency virus) transcription regulation and has other activities. Tat is characterized by high variability, with some amino acid substitutions, including subtypespecific ones, being able to influence on its functionality. HIV type 1 (HIV-1) sub-subtype A6 is the most widespread in Russia. Previous studies of the polymorphisms in structural regions of the A6 variant have shown numerous characteristic features; however, Tat polymorphism in A6 has not been studied.Goals and tasks. The main goal of the work was to analyze the characteristics of Tat protein in HIV-1 A6 variant, that is, to identify substitutions characteristic for A6 and A1 variants, as well as to compare the frequency of mutations in functionally significant domains in sub-subtype A6 and subtype B. MATERIAL AND METHODS: The nucleotide sequences of HIV-1 sub-subtypes A6, A1, A2, A3, A4, subtype B and the reference nucleotide sequence were obtained from the Los Alamos international database. RESULTS AND DISCUSSION: Q54H and Q60H were identified as characteristic substitutions. Essential differences in natural polymorphisms between sub-subtypes A6 and A1 have been demonstrated. In the CPP-region, there were detected mutations (R53K, Q54H, Q54P, R57G) which were more common in sub-subtype A6 than in subtype B. CONCLUSION: Tat protein of sub-subtype A6 have some characteristics that make it possible to reliably distinguish it from other HIV-1 variants. Mutations identified in the CPP region could potentially alter the activity of Tat. The data obtained could form the basis for the drugs and vaccines development.

[Analysis of HIV-1 (Human immunodeficiency virus-1, Lentivirus, Orthoretrovirinae, Retroviridae) Nef protein polymorphism of variants circulating in the former USSR countries.]

INTRODUCTION: The human immunodeficiency virus (HIV) Nef protein is one of the key factors determining the infectivity and replicative properties of HIV. With the ability to interact with numerous proteins of the host cell, this protein provides the maximum level of virus production and protects it from the immune system. The main activities of Nef are associated with a decrease in the expression of the CD4 receptor and major histocompatibility complex class I molecules (MHC-I), as well as the rearrangement of the cytoskeleton. These properties of the protein are determined by the structure of several motifs in the structure of the nef gene encoding it, which is quite variable. OBJECTIVES: The main goal of the work was to analyze the characteristics of Nef protein of HIV-1 variant A6, which dominates in the countries of the former USSR. The objective of the work was a comparative analysis of natural polymorphisms in the nef gene of HIV-1 sub-subtypes A6 and A1 and subtype B. MATERIAL AND METHODS: The sequences of the HIV-1 genome obtained during the previous work of the laboratory were used, as well as the reference sequence from GenBank. In this work, Sanger sequencing and new generation sequencing methods, as well as bioinformation analysis methods were used. RESULTS AND DISCUSSION: The existence of noticeable differences in the prevalence of Nef natural polymorphisms (A32P, E38D, I43V, A54D, Q104K, H116N, Y120F, Y143F, V168M, H192T, V194R, R35Q, D108E, Y135F, E155K, E182M, R184K and F191L), some of which are characteristic mutations for variant A6, was shown. CONCLUSION: Characteristic substitutions were found in the Nef structure, potentially capable of weakening the replicative properties of HIV-1 variant A6.

Evaluating the accuracy and sensitivity of detecting minority HIV-1 populations by Illumina next-generation sequencing.

The accuracy and sensitivity of deep sequencing were assessed using viral standards (pNL4-3 and pLAI.2) of both DNA and RNA. The sequencing accuracy did not depend on the type of nucleic acid, but critically depended on the number of reads and threshold of sensitivity to minor viral populations. With coverage of more than 236 reads, the accuracy of viral RNA sequencing was equal to or exceeded 99.9%, with a sensitivity threshold to minor nucleotides of 20%. When the sensitivity threshold was below 1%, reduced accuracy dynamics were clearly visible even when the coverage was massive (more than 9.000 reads). It was found that the floating sensitivity threshold allowed the sequencing accuracy to be maintained at an acceptable level in cases of low coverage (less than 1.500-2.000) of reads. These results indicate the quality that can be expected with a specific number of reads and sensitivity threshold. Deep sequencing is a very powerful tool that can significantly improve the value of study results, but despite its superior performance, it should be used with caution regarding its sensitivity to minor populations below 1%.

[Molecular epidemiological analysis of HIV-1 variants circulating in Russia in 1987-2015]. / Molekuliarno-épidemiologicheskii analiz variantov VICh-1, tsirkulirovavshikh v Rossii v 1987-2015 gg.

AIM: To simultaneously analyze HIV-1 samples from all Russian regions to characterize the epidemiology of HIV infection in the country as a whole. SUBJECTS AND METHODS: The most extensive study was conducted to examine nucleotide sequences of the pol gene of HIV-1 samples isolated from HIV-positive persons in different regions of Russia, with the diagnosis date being fixed during 1987-2015. The nucleotide sequences of the HIV-1 genome were analyzed using computer programs and on-line applications to identify a virus subtype and new recombinant forms. RESULTS: The nucleotide sequences of the pol gene were analyzed in 1697 HIV-1 samples and the findings were that the genetic variant subtype A1 (IDU-A) was dominant throughout the entire territory of Russia (in more than 80% of all infection cases). Other virus variants circulating in Russia were analyzed; the phenomenon of the higher distribution of the recombinant form CRF63/02A in Siberia, which had been previously described in the literature, was also confirmed. Four new recombinant forms generated by the virus subtype A1 (IDU-A) and B and two AG recombinant forms were found. There was a larger genetic distance between the viruses of IDU-A variant circulating among the injecting drug users and those infected through heterosexual contact, as well as a change in the viruses of subtype G that caused the outbreak in the south of the country over time in 1988-1989. CONCLUSION: The findings demonstrate continuous HIV-1 genetic variability and recombination over time in Russia, as well as increased genetic diversity with higher HIV infection rates in the population.

[The first experience of application of standardized genotype technique of identification of HIV-tropism].

The antagonists of co-receptor CCR5 are an ultimately new class of preparations to treat HIV-infection. The mechanism of action of the preparations of this class is in the selective binding with co-receptor CCR5. This process results in the prevention of penetration of HIV into cell. Before prescribing the CCR5 antagonists the detection of viral tropism has to be done. Recently, in Russia the genotype technique of tropism detection was registered which can be used in clinical practice. The present article describes first experience of application of the given technique to clinical samples. The high correlation was established while comparing with the results of reference laboratory.