Op in C-count to minimally 13.7 . Among the ovine/caprine lentiviruses, the
Op in C-count to minimally 13.7 . Among the ovine/caprine lentiviruses, the nucleotide composition differs significantly between subgroups. Caprine arthritisencephalitis virus (CAEV) subtype E isolates have Anucleotide levels as low as 33.9 , while viruses labelled maedi-visna virus have increased A-levels reaching 37.2 . CAEV non-E subtypes together with viruses classified as ovine lentiviruses display frequencies of Anucleotides up to 38.0 .Table 3 Nucleotide composition of the different HIV-1 subtypes (group M)Comparison Subtype B/subtype Ab Subtype B/subtype C Subtype A/subtype C Subtype B/subtype D Subtype A/subtype D Subtype C/subtype D Subtype A/subtype G Subtype A/CRF02_AG Subtype G/CRF02_AGa bP-valuea for A-content difference 0.0008 0.0002 0.03 <0.0001 <0.0001 <0.0001 <0.0001 0.84 <0.P-value for C-content difference 0.003 <0.0001 0.03 0.70 0.20 0.02 0.88 0.25 0.P-value for G-content difference 0.01 <0.0001 0.007 <0.0001 <0.0001 <0.0001 <0.0001 1.00 <0.P-value for U-content difference 0.03 0.0004 0.12 0.29 0.22 0.009 0.04 0.30 0.Differences in nucleotide composition between HIV-1 subtypes were analysed using Student's t-test. Based on 41 subtype B, 62 subtype A, 55 subtype C, 38 subtype D, 18 PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/26740125 subtype G and 32 recombinant CRF02_AG gag-pol-env sequences.van der Kuyl and Berkhout Retrovirology 2012, 9:92 http://www.retrovirology.com/content/9/1/Page 4 ofAmong lentivirus groups for which more than a single isolate could be analysed, the percentage of each nucleotide is stable, and the overall nucleotide composition serves as a distinguishing trait. For instance, HIV-2 is the only lentivirus that has similar levels of C and U nucleotides (20.4 and 20.7 , respectively), and this characteristic is found in all full-length HIV-2 genomes available, except for one that was described as a highly divergent strain of HIV-2, probably originating from another zoonotic transmission [16].>Nucleotide composition of HIV-1 over timeThe nucleotide composition of HIV-1 has remained remarkably constant over the three decades that virus variants from the current epidemic have been monitored (Table 4). Early isolates (1983?997) of HIV-1 group M (analysed for subtypes A and B), N, and O viruses do not significantly Valsartan/sacubitril chemical information differ from more recent isolates (1998?009) with regard to nucleotide composition (Table 4). Comparing isolates obtained before 1990 to isolates obtained after the year 2000, or other variations of the time window, didnot change the results (not shown). This suggests that the precise nucleotide composition of the HIV-1 genome, and most likely of other lentivirus genomes is a stable and PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/28893839 unique trait that is highly preserved throughout evolution. Unfortunately, of the early HIV-1 group M viruses from 1959 and 1960, only very short fragments (< 200 nucleotides) have been amplified, from which the genomic nucleotide composition cannot be reliably estimated [17,18]. For HIV-1 group O, a total of 1770 nucleotides of four pol gene fragments are available for an isolate recovered from autopsy material collected in 1976 of a father and daughter infected in the 1960s [19]. The base composition of these combined fragments is 39.7 A, 15.6 C, 22.4 G and 21.8 U, which, except for G, falls within the range of the base composition of homologous pol gene fragments from group O isolates from 1986?995 (ANT70 from 1986 acc. no. L20587; MVP5180 from 1991 acc. no. L20571; pCMO2.3 from 1995 acc. no. AY618998): 39.2-40.3 A, 14.7-15.7 C, 22.7-23.6 G and 21.9-.
