Classifying genotype F of hepatitis B virus into F1 and F2 subtypes

AIM： To explore the propriety of providing hepatitis B virus （HBV） genotypes F and H with two distinct genotypes. METHODS： Eleven HBV isolates of genotype F （HBV/F） were recovered from patients living in San Francisco, Japan, Panama, and Venezuela, and their full-length sequences were determined. Phylogenetic analysis was carded out among them along with HBV isolates previously reported. RESULTS： Seven of them clustered with reported HBV/F Isolates in the phylogenetic tree constructed on the entire genomic sequence. The remaining four flocked on another branch along with three HBV isolates formerly reported as genotype H. These seven HBV isolates, including the four in this study and the three reported, had a sequence divergence of 7.3-9.5% from the other HBV/F isolates, and differed by 〉13.7% from HBV isolates of the other six genotypes （A-E and G）. Based on a marked genomic divergence, falling just short of 〉8% separating the seven genotypes, these seven HBV/F isolates were classified into F2 subtype and the former seven into F1 subtype provisionally. In a pairwise comparison of the S-gene sequences among the 7 HBV/F2 isolates and against 47 HBV/F1 isolates as well as 136 representing the other six genotypes （A-E and G）, two clusters separated by distinct genetic distances emerged.CONCLUSION： Based on these analyses, dassifying HBV/ F isolates into two subtypes （F1 and F2） would be more appropriate than providing them with two distinct genotypes （F and H）.

The complete mitochondrial genome of Anopheles minimus （Diptera： Culicidae） and the phylogenetics of known Anopheles mitogenomes

Anopheles minimus is an important vector of human malaria in southern China and Southeast Asia. The phylogenetics of mosquitoes has not been well resolved, and the mitochondrial genome （mtgenome） has proven to be an important marker in the study of evolutionary biology. In this study, the complete mtgenome of An. minimus was sequenced for the first time. It is 15 395 bp long and encodes 37 genes, including 13 protein-coding genes （PCGs）, 22 transfer RNAs （tRNAs）, two ribosomal RNAs （rRNAs） and a non-coding region. The gene organization is consistent with those of known Anopheles mtgenomes. The mtgenome performs a clear bias in nucleotide composition with a positive AT-skew and a negative GC-skew. All 13 PCGs prefer to use the codon UUA （Leu）, ATN as initiation codon but cytochrome-oxidase subunit 1 （COI） and ND5, with TCG and GTG, and TAA as termination codon, but COI, COII, COIII and ND4, all with the incomplete T. tRNAs have the typical clover-leaf structure, but tRNAser^a~N） is consistent with known Anopheles mtgenomes. The control region includes a conserved T-stretch and a （TA）n stretch, and has the highest A＋T content at 93.1%. The phylogenetics of An. minimus with 18 other Anopheles species was constructed by maximum likelihood and Bayesian inference, based on concatenated PCG sequences. The subgenera, Cellia and Anopheles, and Nyssorhynchus and Kerteszia have mutually close relationships, respectively. The Punctulatus group and Leueosphyrus group of Neomyzomyia Series, and the Albitarsis group of Albitarsis Series were suggested to be monophyletic. The monophyletic status of the subgenera, Cellia, Anopheles, Nyssorhynchus and Kerteszia need to be further elucidated.