Screening of HIV-1 isolates by reverse heteroduplex mobility assay and identification of non-B subtypes in Italy.
OBJECTIVE
The increasing prevalence of HIV-1 transmission through heterosexual contacts and the growing number of immigrants from non-Western countries, where non-B subtypes and recombinant forms are prevalent, suggest the possible emergence in Italy of a new epidemic wave of HIV-1 non-B subtypes as well as recombinant forms.


METHODS
The distribution of HIV-1 subtypes has been evaluated in 63 seropositive individuals residing in Italy, most of whom were infected through a sexual route during the last 5 years. A modified heteroduplex mobility assay (HMA) strategy, reverse HMA (rHMA), has been developed in our laboratory, allowing rapid identification of divergent-from-B-subtype isolates, which have been subsequently characterized by detailed molecular and phylogenetic analyses.


RESULTS
Five samples show, on rHMA, an electrophoretic pattern compatible with a non-B subtype classification. Their phylogenetic analysis, performed on both env and gag regions, confirms the rHMA subtyping prediction, given that 3 samples fall into the "A-family" subtype and 2 into the G subtype. The 5 non-B-subtype HIV-1 isolates have been identified among 23 variants (prevalence, 21.74%) isolated during the 2000 to 2001 period in heterosexuals. In parallel, B-subtype isolates show high levels of intrasubtype nucleotide divergence, compatible with a constant HIV-1 molecular diversification.


CONCLUSIONS
The Italian HIV-1 epidemic is still mostly attributable to the B subtype, which shows an increasing nucleotide heterogeneity. Heterosexual transmission and the interracial blending, however, are slowly introducing novel HIV-1 subtypes, and the data indicate that rHMA represents a powerful tool for HIV-1 biomolecular screening in epidemics characterized by a mono-/dual-subtype predominance.
Buonaguro
Luigi
L
Viral Oncology and AIDS Refer. Center, Ist. Naz. Tumori Fond. G. Pascale, Naples, Italy.
Tagliamonte
Maria
M
Tornesello
Maria Lina
ML
Pilotti
Elisabetta
E
Casoli
Claudio
C
Lazzarin
Adriano
A
Tambussi
Giuseppe
G
Ciccozzi
Massimo
M
Rezza
Giovanni
G
Buonaguro
Franco M
FM
D000328:Adult; D004279:DNA, Viral / Q000032:analysis / Q000097:blood; D005260:Female; D015752:Genes, env; D015658:HIV Infections / Q000635:transmission* / Q000821:virology; D006679:HIV Seropositivity; D015497:HIV-1 / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D020180:Heteroduplex Analysis / Q000379:methods*; D006801:Humans; D007558:Italy; D008297:Male; D009692:Nucleic Acid Heteroduplexes; D010802:Phylogeny; D017422:Sequence Analysis, DNA
D004279:DNA, Viral; D009692:Nucleic Acid Heteroduplexes