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Increasing HIV drug resistance is an important public health concern. The current study aimed to assess HIV drug resistance among people who live with HIV (PLWH) experiencing virological failure. Blood samples and epidemiological characteristics were collected in four Siberian regions from PLWH experiencing ART failure. Partial pol gene sequences were obtained for the study individuals. Drug resistance mutations (DRMs) were predicted using the Stanford HIVdb Program. The association of HIV DRM with epidemiological characteristics was estimated using logistic regression analysis. Further analysis was performed for children (0-14 y old) and adults (≥15 y old) separately. In total, 815 (89.4%) patients were included in the final dataset. Overall, 501 (61.5%) patients had DRM detected. NRTI DRM was more common in children, while NRTI+NNRTI DRM was more frequent in adults (P < 0.001). Krasnoyarsk region, male sex and high viral load were positively associated with the presence of DRM in adults, while higher CD4 cell count and PI/INSTI-based ART had a negative association. No association between epidemiological characteristics and DRM was identified in children. The remaining 38.5% of patients with virological failure had no DRM detected; those patients were likely to have insufficient ART adherence. Most (55.5%) patients had HIV CRF63&#95;02A6, followed by sub-subtype A6 (39.2%). This study revealed poor ART adherence as a main factor driving ART failure among PLWH in the Siberian region. DRM was detected in over 60% of PLWH experiencing ART failure. The current results highlight an urgent need for the introduction of special programs focusing on ART adherence improvement., (Copyright © 2023 Elsevier Ltd and International Society of Antimicrobial Chemotherapy. All rights reserved.)

Objectives: Antiretroviral (ARV) drugs have played a vital role in controlling the HIV-1 epidemic; however, some challenges remain. ARV drugs vary in their ability to control HIV infection, displaying differences in treatment-limiting factors and genetic barriers to resistance. The current report assesses the prevalence of HIV-1 drug resistance mutations (DRMs) among patients who failed first-line antiretroviral therapy (ART) and evaluates the genetic barrier of different regimens., Methods: The study cohort (n = 271) included HIV-infected individuals who visited the Novosibirsk, Russia, HIV/AIDS clinic in 2018-2022. All patients received first-line ART prior to virological failure. Sociodemographic and HIV-related data were collected from medical records and self-reported questionnaires. HIV-1 pol gene sequences were generated, and the presence of HIV-1 DRM was assessed. The genetic barrier to resistance was assessed by combining treatment regimen and adherence data., Results: Nonoptimal ART adherence was identified in 48.3% of patients and correlated with male sex, PWID, unemployment, and rural area residence. Most of the patients with high-level adherence were identified among those who were on TDF+3TC+DTG. HIV-1 DRMs were identified in 54.6% of the patients. The analysis of HIV-1 DRM, ART regimen, and adherence data classified TDF+3TC+DTG and TDF+3TC+LPV/r as treatment regimens with a high genetic barrier, whereas EFV-containing ART was classified as a regimen with a low genetic barrier., Conclusions: The current study delivers results on the efficacy of HIV-1 ART and treatment adherence in real-world practice settings. This report suggests that ART regimens with a high genetic barrier to resistance combined with improved treatment adherence may reduce the transmission of HIV-1 resistant variants., (Copyright © 2023 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

HIV-1 epidemic in Russia is one of the fastest growing in the world reaching 1.14 million people living with HIV-1 (PLWH) in 2021. Since mid-1990s, the HIV-1 epidemic in Russia has started to grow substantially due to the multiple HIV-1 outbreaks among persons who inject drugs (PWID) leading to expansion of the HIV-1 sub-subtype A6 (former Soviet Union (FSU) subtype A). In 2006, a local HIV-1 sub-epidemic caused by the distribution of novel genetic lineage CRF63&#95;02A6 was identified in Siberia. In this study, we used a comprehensive dataset of CRF63&#95;02A6 pol gene sequences to investigate the spatiotemporal dynamic of the HIV-1 CRF63&#95;02A6 sub-epidemic. This study includes all the available CRF63&#95;02A6 HIV-1 pol gene sequences from Los Alamos National Laboratory (LANL) HIV Sequence Database. The HIV-1 subtypes of those sequences were conferred using phylogenetic analysis, and two automated HIV-1 subtyping tools Stanford HIVdb Program and COMET. Ancestral state reconstruction and origin date were estimated using Nextstrain. Evolutionary rate and phylodynamic analysis were estimated using BEAST v 1.10.4. CRF63&#95;02A6 was assigned for 872 pol gene sequences using phylogenetic analysis approach. Predominant number (n = 832; 95.4%) of those sequences were from Russia; the remaining 40 (4.6%) sequences were from countries of Central Asia. Out of 872 CRF63&#95;02A6 sequences, the corresponding genetic variant was assigned for 75.7 and 79.8% of sequences by Stanford and COMET subtyping tools, respectively. Dated phylogenetic analysis of the CRF63&#95;02A6 sequences showed that the virus most likely originated in Novosibirsk, Russia, in 2005. Over the last two decades CRF63&#95;02A6 has been widely distributed across Russia and has been sporadically detected in countries of Central Asia. Introduction of new genetic variant into mature sub-subtype A6 and CRF02&#95;AG FSU epidemics could promote the increase of viral genetic diversity and emergence of new recombinant forms. Further HIV-1 studies are needed due to a continuing rapid virus distribution. Also, the implementation of HIV-1 prevention programs is required to reduce HIV-1 transmission. This study also highlights the discrepancies in HIV-1 subtyping approaches. The reference lists of HIV-1 sequences implemented in widely used HIV-1 automated subtyping tools need to be updated to provide reliable results., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Sivay, Maksimenko, Osipova, Nefedova, Gashnikova, Zyryanova, Ekushov, Totmenin, Nalimova, Ivlev, Kapustin, Pozdnyakova, Skudarnov, Ostapova, Yaschenko, Nazarova, Chernov, Ismailova, Maksutov and Gashnikova.)

Kyrgyzstan has one of the highest rates of HIV-1 spread in Central Asia. In this study, we used molecular-epidemiological approaches to examine the HIV-1 epidemic in Kyrgyzstan. Samples were obtained from HIV-positive individuals who visited HIV/AIDS clinics. Partial pol gene sequences were used to identify HIV-1 subtypes and drug resistance mutations (DRMs) and to perform phylogenetic analysis. Genetic diversity and history reconstruction of the major HIV-1 subtypes were explored using BEAST. This study includes an analysis of 555 HIV-positive individuals. The study population was equally represented by men and women aged 1-72 years. Heterosexual transmission was the most frequent, followed by nosocomial infection. Men were more likely to acquire HIV-1 during injection drug use and while getting clinical services, while women were more likely to be infected through sexual contacts ( p < 0.01). Heterosexual transmission was the more prevalent among individuals 25-49 years old; individuals over 49 years old were more likely to be persons who inject drugs (PWID). The major HIV-1 variants were CRF02&#95;AG, CRF63&#95;02A, and sub-subtype A6. Major DRMs were detected in 26.9% of the study individuals; 62.2% of those had DRMs to at least two antiretroviral (ARV) drug classes. Phylogenetic analysis revealed a well-defined structure of CRF02&#95;AG, indicating locally evolving sub-epidemics. The lack of well-defined phylogenetic structure was observed for sub-subtype A6. The estimated origin date of CRF02&#95;AG was January 1997; CRF63&#95;02A, April 2004; and A6, June 1995. A rapid evolutionary dynamic of CRF02&#95;AG and A6 among Kyrgyz population since the mid-1990s was observed. We observed the high levels of HIV-1 genetic diversity and drug resistance in the study population. Complex patterns of HIV-1 phylogenetics in Kyrgyzstan were found. This study highlights the importance of molecular-epidemiological analysis for HIV-1 surveillance and treatment implementation to reduce new HIV-1 infections., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Sivay, Totmenin, Zyryanova, Osipova, Nalimova, Gashnikova, Ivlev, Meshkov, Chokmorova, Narmatova, Motorov, Akmatova, Asybalieva, Bekbolotov, Kadyrbekov, Maksutov and Gashnikova.)

More than a quarter of HIV-infected individuals registered in Russia live in Siberia. Unlike Central Russia where HIV-1 subtype A6 is predominant, in most Siberian regions since 2012, a new HIV-1 CRF63&#95;02A1 genetic variant has spread, with the share of this variant attaining 75-85% among newly identified HIV cases. Krasnoyarsk Krai is considered to be a high-risk territory according to morbidity rate and HIV infection incidence among the population. The current paper aims to study the molecular epidemiologic characteristics of HIV-1 spreading in Krasnoyarsk Krai. Phylogenetic and recombination analyses of pol (PR-RT, IN) and env regions of the virus were used for genotyping 159 HIV-1 isolated in Krasnoyarsk Krai. 57.2% of the isolates belonged to subtype A (A6) specific to Russia, 12.6% to CRF63&#95;02A1, and 0.6% to CRF02&#95;AG СА , and in 29.6% HIV-1 URFs were detected, including URF63/А (23.9%), URFА/В (4.4%), and URF02/А (1.3%). In 6 of 7, HIV-1 URFА/В identical recombination model was detected; the origin of 38 URF63/А was proven to be the result of individual recombination events. Since 2015, a share of the population with newly diagnosed HIV who were infected with HIV-1 URF reached an exceptionally high rate of 38.6%. As distinct from adjacent Siberian regions, the HIV-1 CRF63&#95;02A1 prevalence rate in Krasnoyarsk Krai is within 16%; however, the increased contribution of new HIV-1 into the regional epidemic development was observed due to the recombination of viruses of subtypes А, В, and CRF63&#95;02A1. The difference between the described molecular epidemiologic picture in Krasnoyarsk Krai and in adjacent areas is likely caused by differences in predominant routes of HIV transmission and by more recent HIV-1 CRF63&#95;02A1 transmission in the PWID group, which had a high prevalence of HIV-1 subtype A by the time of the new virus transmission, resulting in increased possibility of coinfection with various HIV-1 genetic variants., Competing Interests: The authors declare that there are no conflicts of interest regarding the publication of this paper., (Copyright © 2020 Lada V. Maksimenko et al.)

Currently, HIV-1 CRF63&#95;02A6 is the prevalent genetic variant of the HIV-infected subjects in the major part of the Siberian Federal District (Russia). The HIV-1 CRF63&#95;02A6 R5-tropic pT11.17 and X4-tropic pMtBs.18 infectious molecular clones (IMCs) were constructed using the virus isolates recovered in 2015 and 2017 of male HIV-infected Russian residents (from Tomsk and Novosibirsk, respectively). Near full-length proviral HIV-1 sequences (9,644 and 9,748 bp) were subcloned in pBluescript II KS(-). The CRF63&#95;02A6 IMC virions were obtained by transfecting HEK293T cells with the constructed plasmids and demonstrated a stable growth in peripheral blood mononuclear cell culture (p24 concentration increased >1,000-fold and the virus protein accumulation in culture liquid exceeded 100,000 pg/mL). The tropism of CRF63&#95;02A6 IMCs was determined genotypically (using Geno2pheno) and phenotypically by cultivating the IMC virions in MT-2, U87-CD4-CCR5, and U87-CD4-CXCR4 cell cultures. The obtained HIV-1 CRF63&#95;02A6 IMCs may be useful in basic and applied research.

The high genetic variability of the human immunodeficiency virus (HIV-1) leads to a constant emergence of new genetic variants, including the recombinant virus CRF63&#95;02A1, which is widespread in the Siberian Federal District of Russia. We studied HIV-1 CRF63&#95;02A1 integrase (IN&#95;CRF) catalyzing the incorporation of viral DNA into the genome of an infected cell. The consensus sequence was designed, recombinant integrase was obtained, and its DNA-binding and catalytic activities were characterized. The stability of the IN&#95;CRF complex with the DNA substrate did not differ from the complex stability for subtype A and B integrases; however, the rate of complex formation was significantly higher. The rates and efficiencies of 3'-processing and strand transfer reactions catalyzed by IN&#95;CRF were found to be higher, too. Apparently, all these distinctive features of IN&#95;CRF may result from specific amino acid substitutions in its N-terminal domain, which plays an important role in enzyme multimerization and binding to the DNA substrate. It was also found that the drug resistance mutations Q148K/G140S and G118R/E138K significantly reduce the catalytic activity of IN&#95;CRF and its sensitivity to the strand transfer inhibitor raltegravir. Reduction in sensitivity to raltegravir was found to be much stronger in the case of double-mutation Q148K/G140S.

Kemerovo Oblast (KO) has had the highest rate of HIV spread in Russia since 2011. The aim of this work was to study the genetic variation of HIV-1 in Kemerovo Oblast. Blood was sampled from a total of 91 HIV-positive antiretroviral-therapy-naïve individuals in 2013 (38) and 2015 (53). HIV-1 subtypes, pol gene drug resistance mutations, and viral tropism were analyzed. In 2013-2015, the prevalence of HIV-1 subtype A decreased in KO from 60.5 to 7.5 %. The samples collected in 2015 from the patients with newly diagnosed HIV demonstrate the current dominance of HIV-1 CRF63&#95;02A1 (71.7 %) and HIV-1 URF63&#95;A1 (20.8 %), their parental viruses being CRF63&#95;02A1 and subtype A. The initially predominant genetic variant, HIV-1 subtype A, was replaced in KO. An unusually high incidence of HIV-1 unique recombinant forms is probably the result of HIV-1 CRF63&#95;02A1 introduction in the group of injection drug users with the initial HIV-1 subtype A infection and the practice of risky behavior that promotes reinfection. HIV-1 CRF63&#95;02A1, which recently emerged in Siberia, and its recombinant forms have an ever-increasing impact on the current HIV epidemic in Russia, making urgent the need for in-depth study of this HIV-1 genetic variant.

Introduction . Specific molecular epidemic features of HIV infection in Tyumen Oblast (TO), Russia, were studied. Methods . The genome sequences encoding HIV-1 protease-reverse transcriptase, integrase, and major envelope protein were examined for 72 HIV-1 specimens isolated from the TO resident infected in 2000-2015. Results . The recorded prevalence of HIV-1 subtype A (A1) is 93.1%; HIV-1 subtype B continues to circulate in MSM risk group (1.4%). Solitary instances of HIV-1 recombinant forms, CRF63&#95;02A1 (1.4%) and CRF03&#95;AB (1.4%), were detected as well as two cases of HIV-1 URF63&#95;A1 (2.8%). Phylogenetic analysis showed no HIV-1 clustering according to the duration of infection and risk groups but revealed different epidemic networks confirming that HIV infection spread within local epidemic foci. A high incidence of CXCR4-tropic HIV-1 variants and a higher rate of secondary mutations influencing the virus fitness (K20R, L10V, and I) are observed among the virus specimens isolated from newly infected individuals. Conclusions . The current HIV-1 epidemic in TO develops within the local epidemic networks. Similar to the previous period, HIV-1 subtype A is predominant in TO with sporadic cases of importation of HIV-1 recombinant forms circulating in adjacent areas., Competing Interests: The authors declare that there is no conflict of interests regarding the publication of this paper.

The prevalence of HIV infection in different Russian regions is nonuniform. In the Tomsk region (TR), 2020 HIV new infection cases were recorded in 2013, the morbidity having increased 5.9-fold as compared to 2012. In total, 64 blood plasma samples from primary HIV cases have been examined. HIV-specific fragments of the pol gene have been obtained for 61 samples (of protease for 58 and of integrase for 23) and of the env gene V3 region for 40 samples. Phylogenetic analysis of the determined HIV-1 sequences has detected CRF63&#95;02A1 in 55 (90.2%) cases, whereas HIV subtype A1, characteristic of Russia, has been observed in only three (4.9%) patients. Three (4.9%) cases contain CRF63&#95;02A1/A recombinant variants. This article demonstrates that a drastic activation of the epidemic in the Tomsk region is accompanied by a rapid spreading of the recently described HIV-1 CRF63&#95;02A1, which we detected in the Novosibirsk region outbreak of 2008.

Monkeypox virus (MPV) belongs to the orthopoxvirus genus of the family Poxviridae, is endemic in parts of Africa, and causes a human disease that resembles smallpox. The 196,858-bp MPV genome was analyzed with regard to structural features and open reading frames. Each end of the genome contains an identical but oppositely oriented 6379-bp terminal inverted repetition, which similar to that of other orthopoxviruses, includes a putative telomere resolution sequence and short tandem repeats. Computer-assisted analysis was used to identify 190 open reading frames containing >/=60 amino acid residues. Of these, four were present within the inverted terminal repetition. MPV contained the known essential orthopoxvirus genes but only a subset of the putative immunomodulatory and host range genes. Sequence comparisons confirmed the assignment of MPV as a distinct species of orthopoxvirus that is not a direct ancestor or a direct descendent of variola virus, the causative agent of smallpox.

Monkeypox virus (MPV) causes a human disease which resembles smallpox but with a lower person-to-person transmission rate. To determine the genetic relationship between the orthopoxviruses causing these two diseases, we sequenced the 197-kb genome of MPV isolated from a patient during a large human monkeypox outbreak in Zaire in 1996. The nucleotide sequence within the central region of the MPV genome, which encodes essential enzymes and structural proteins, was 96.3% identical with that of variola (smallpox) virus (VAR). In contrast, there were considerable differences between MPV and VAR in the regions encoding virulence and host-range factors near the ends of the genome. Our data indicate that MPV is not the direct ancestor of VAR and is unlikely to naturally acquire all properties of VAR.

Vaccinia virus complement control protein (VCP) has been shown to possess the ability to inhibit both classical and alternative complement pathway activation. The newly found ability of this protein to bind to heparin has been shown in previous studies to result in uptake by mast cells, possibly promoting tissue persistence. It has also been shown to reduce chemotactic migration of leukocytes by blocking chemokine binding. In addition, this study shows that VCP-through its ability to bind to glycosaminoglycans (heparin-like molecules) on the surface of human endothelial cells-is able to block antibody binding to surface major histocompatibility complex class I molecules. Since heparin binding is critical for many functions of this protein, we have attempted to characterize the molecular basis for this interaction. Segments of this protein, generated by genetic engineering of the DNA encoding VCP into the Pichia pastoris expression system, were used to localize the regions with heparin binding activity. These regions were then analyzed to more specifically define their properties for binding. It was found that the number of putative binding sites (K/R-X-K/R), the overall positive charge, and the percentage of positively charged amino acids within the protein were responsible for this interaction.

Alastrim variola minor virus, which causes mild smallpox, was first recognized in Florida and South America in the late 19th century. Genome linear double-stranded DNA sequences (186,986 bp) of the alastrim virus Garcia-1966, a laboratory reference strain from an outbreak associated with 0.8% case fatalities in Brazil in 1966, were determined except for a 530-bp fragment of hairpin-loop sequences at each terminus. The DNA sequences (EMBL Accession No. Y16780) showed 206 potential open reading frames for proteins containing >/=60 amino acids. The amino acid sequences of the putative proteins were compared with those reported for vaccinia virus strain Copenhagen and the Asian variola major strains India-1967 and Bangladesh-1975. About one-third of the alastrim viral proteins were 100% identical to correlates in the variola major strains and the remainder were >/=95% identical. Compared with variola major virus DNA, alastrim virus DNA has additional segments of 898 and 627 bp, respectively, within the left and right terminal regions. The former segment aligns well with sequences in other orthopoxviruses, particularly cowpox and vaccinia viruses, and the latter is apparently alastrim-specific., (Copyright 2000 Academic Press.)

Microorganisms encode numerous immunomodulators that resemble, in structure and function, molecules captured over the millennia from their hosts [G. J. Kotwal J. Leukoc. Biol. 62, 415-429]. The vaccinia virus complement control protein (VCP) was the first soluble microbial protein to have a postulated role in the immunomodulation and evasion of host defense [G. J. Kotwal and B. Moss Nature 355, 176-179]. Purified bioactive VCP has been shown to bind to C3 and C4, block the complement cascade at multiple sites [G. J. Kotwal et al. Science 250, 827-830; R. Mckenzie, G. J. Kotwal et al. J. Infect. Dis. 166, 1245-1250] and exhibit a greater potency than the human complement 4b binding protein, C4b-BP [G. J. Kotwal, Am. Biotech. Lab. 9, 76]. The importance of this protein to poxviruses was further demonstrated in rabbits and guinea pigs through the use of recombinant virus lacking an intact DNA coding for VCP [Isaacs, G. J. Kotwal, and B. Moss Proc. Natl. Acad. Sci. 89, 628-672]. Studies in mice have shown that the homolog of VCP in cowpox virus (CPV), referred to as the inflammation modulatory protein (IMP) can, in a mouse model, significantly diminish the specific footpad swelling response [C. G. Miller, S. N. Shchelkunov, and G. J. Kotwal Virol. 229, 126-133]. To determine the precise cellular changes at the site of infection, BALB/c mice were subcutaneously injected (in the backs) with CPV or a recombinant virus lacking IMP, CPV-IMP. Differences in histology were observed by staining the adjoining skin tissue sections with hematoxylin & eosin or by removal of the connective tissue and staining with May-Grunwald-Geimsa. All mice that were injected with the CPV-IMP experienced severe tissue destruction and formation of nodular lesions compared with the mice injected with CPV. Microscopic examination indicated significantly greater cellular infiltration and destruction of skeletal muscle cells in the sections of connective tissue and adjoining skin tissue, respectively, of the mice injected with the CPV-IMP [G. J. Kotwal et al. Mol. Cell. Biochem. in press]. Thus IMP preserves the tissue at the site of infection (viral habitat). In this review, we present evidence for molecular mimicry and evolutionary relationship to other homologs of IMP and discuss their relationships with other IMPs such as the poxviral chemokine and cytokine receptor-like proteins.

Sequencing and computer analysis of the left (52,283 bp) and right (49,649 bp) variable DNA regions of the cowpox virus strain GRI-90 (CPV-GRI) has revealed 51 and 37 potential open reading frames (ORFs), respectively. Comparison of the structure-function organization of these DNA regions of CPV-GRI with those previously published for corresponding regions of genomes of vaccinia virus, strains Copenhagen (VAC-COP) and Western Reserve (VAC-WR); and variola major virus, strains India-1967 (VAR-IND), Bangladesh-1975 (VAR-BSH); and alastrim variola minor virus, strain Garcia-1966 (VAR-GAR), was performed. Within the left terminal region under study, an extended DNA sequence (14,171 bp), unique to CPV, has been found. Within the right region of the CPV-GRI genome two segments, which are unique to CPV DNA (1579 and 3585 bp) have been found. Numerous differences have been revealed in the genetic structure of CPV-GRI DNA regions, homologous to fragments of the genomes of the above-mentioned orthopoxvirus strains. A cluster of ORFs with structural similarity ot immunomodulatory and host range function of other poxviruses have also been detected. A comparison of the sequences of ORF B, crmA, crmB, crmC, IMP, and CHO hr genes of CPV Brighton strain (CPV-BRI) with the corresponding genes in strain GRI-90 have revealed an identity at the amino acid level ranging from 82 to 96% between the two strains. The findings are significant in light of the recent demonstration of CPV as an important poxvirus model system to probe the precise in vivo role(s) of the unique virally encoded immunomodulatory proteins. Also, the presence of a complete and intact repertoire of immunomodulatory proteins, ring canal proteins family, and host range genes indicates that CPV may have been the most ancient of all studied orthopoxviruses.

Genome DNA terminal region sequences were determined for a Brazilian alastrim variola minor virus strain Garcia-1966 that was associated with an 0.8% case-fatality rate and African smallpox strains Congo-1970 and Somalia-1977 associated with variola major (9.6%) and minor (0.4%) mortality rates, respectively. A base sequence identity of > or = 98.8% was determined after aligning 30 kb of the left- or right-end region sequences with cognate sequences previously determined for Asian variola major strains India-1967 (31% death rate) and Bangladesh-1975 (18.5% death rate). The deduced amino acid sequences of putative proteins of > or = 65 amino acids also showed relatively high identity, although the Asian and African viruses were clearly more related to each other than to alastrim virus. Alastrim virus contained only 10 of 70 proteins that were 100% identical to homologs in Asian strains, and 7 alastrim-specific proteins were noted.

Sequencing and computer analysis of the nucleotide sequence of variola major virus strain India-1967 (VAR-IND) DNA segment (23 786 bp) covering the left variable region of the viral genome has been carried out. Twenty-nine potential open reading frames were identified. Structure-function organization of the VAR-IND DNA segment was compared with previously reported sequences from analogous genome regions of vaccinia virus strains Copenhagen (VAC-COP) and Western Reserve (VAC-WR). Multiple structural differences between the VAR-IND and genome regions were analysed and both VAC-COP and VAC-WR have been found. Possible molecular factors of virulence, virus host range genes as well as differences revealed in the structure of these genes of VAR and VAC will be discussed.

The genome nucleotide sequences of two strains of variola major virus and one strain of vaccinia virus were compared. One hundred and sixty-eight short (less than 100 bp in length) and eight long (more than 900 bp in length) deletions, four deletion/insertion regions, and four regions of multiple mutational differences between variola and vaccinia virus DNAs were revealed. Short deletions generally occur at directly repeated sequences of 3-21 bp. Long deletions showed no evidence of repeated sequences at their points of junction. We suggest the presence of a consensus sequence characteristic of these junctions and propose that there is a virus-encoded enzyme that produces this nonhomologous recombination/deletion in the cytoplasm of the infected cell.

Sequencing and computer analysis of a variola major virus strain India-1967 (VAR-IND) genome segment (53,018 bp) from the right terminal region has been carried out. Fifty-nine potential open reading frames (ORFs) of over 60 amino acid residues were identified. Structure-function organization of the VAR-IND DNA segment was compared with the previously reported sequences from the analogous genomic regions of vaccinia virus strains Copenhagen (VAC-COP) and Western Reserve (VAC-WR) and variola virus strain Harvey (VAR-HAR). Multiple differences between VAR-IND and the strains of VAC but the high identity of VAR-IND with VAR-HAR in the genetic maps are revealed. Possible functions of the predicted viral proteins and the effect of their differences on the features of orthopoxviruses are discussed.

Computer analysis of a variola major virus (VAR) genomic fragment bounded by the open reading frames (ORFs) D1R and A33L, which is 47,961 bp long, revealed 46 potential ORFs. The VAR proteins were compared to the analogous proteins of vaccinia virus strain Copenhagen. The subunits of DNA-dependent RNA polymerase, as well as the transcription factors, mRNA-capping enzymes, and proteins necessary for the virion morphogenesis proved to be highly conservative within orthopoxviruses. The most pronounced differences between the VAR genome fragment under study and the corresponding vaccinia virus fragment were revealed in the vicinity of the gene encoding the A-type inclusion bodies protein. Possible functions of the analysed viral proteins are discussed.

Sequencing and computer analysis of the nucleotide sequence of the variola virus strain India-1967 (VAR) genome segment (43069 bp) from the region of HindIII C, E, R, Q, K, H DNA fragments has been carried out. Forty-three potential open reading frames (ORFs) have been identified, and the polypeptides encoded by them have been compared with the analogous proteins of vaccinia virus strain Copenhagen (COP). ORF E7R of VAR is much shorter than the COP analog. The other polypeptides coded by the potential ORFs of VAR are highly conserved in comparison with COP. Possible functions of the predicted viral polypeptides are discussed.

The complete genetic map of the variola major virus strain India-1967 is built basing on the sequence data. The suggested map is compared with the maps of the sequenced genomic regions of Copenhagen and Western Reserve strains of vaccinia virus and Harvey strain of variola major virus. The principle differences revealed in the genomic organization of these viruses are discussed.

DNA of the variola major virus strain India-1967 in the region of HindIII M, L, I fragments has been sequenced. Analysis of this sequence of 18029 bp revealed 19 potential open reading frames (ORFs). Four proposed proteins (L2R, H9R, L5L, L6R) contain metal-binding domains. Comparison of the variola virus (VAR) and vaccinia virus strain Copenhagen (COP) sequences show that the main differences are between proteins L1R and I5R. L1R contains 6 additional amino acid residues on the C-terminus. The protein I5R of VAR contains three Ca2+ binding domains but this COP has deletions in 2 of the 3 established domains. Possible functions of the predicted viral polypeptides are discussed.