High burden of transmitted HIV-1 drug resistance in Italian patients carrying F1 subtype.
BACKGROUND
Transmitted drug resistance (TDR) is mainly restricted to individuals carrying B subtype, with low prevalence among non-B subtypes when grouped together. Subtype F1 is the most frequent non-B variant found in subjects living in Italy, allowing a specific assessment of TDR associated with this clade.


METHODS
We analysed pol sequences of HIV-1-positive individuals carrying the F1 variant included in the Antiretroviral Resistance Cohort Analysis database in the 1998-2009 period. Mutations were analysed with the Surveillance Drug Resistance Mutation and the International AIDS Society lists for naive and treated patients, respectively.


RESULTS
Among 343 HIV-1-infected patients carrying an F1 subtype, resistance was evaluated in a subset of 221 patients whose treatment status was known (169 drug naive and 52 drug experienced). The prevalence of TDR was 15.4% (11.8% for nucleoside/nucleotide reverse transcriptase inhibitors, 6.5% for non-nucleoside reverse transcriptase inhibitors and 7.1% for protease inhibitors). Among the 169 naive patients, 75.1%, 10.1% and 7.1% were Italians, South Americans and Romanians, respectively. Heterosexuals were prevalent among Italians and Romanians, while men who have sex with men were predominant among South Americans. The overall frequency of TDR declined from 21.4% to 7.1% in the 1998-2009 period. Although no statistical difference was detected, the frequency of TDR was higher in South Americans (23.5%) compared with Italian and Romanian naive patients (15% and 8.3%, respectively).


CONCLUSIONS
Our study shows a remarkable frequency of TDR in the F1 subtype-infected population. The high prevalence of TDR detected in South American subjects is linked to the homosexual route of infection. However, TDR was considerably high also in Italian subjects harbouring the F1 subtype, deserving careful monitoring.
Department of Clinical Science L. Sacco, Section of Infectious Diseases and Immunopathology, University of Milan, Milan, Italy. marco.franzetti@unimi.it
Marco
M
Franzetti
Alessia
A
Lai
Francesco Roberto
FR
Simonetti
Giorgio
G
Bozzi
Andrea
A
De Luca
Valeria
V
Micheli
Paola
P
Meraviglia
Paola
P
Corsi
Patrizia
P
Bagnarelli
Paolo
P
Almi
Alessia
A
Zoncada
Claudia
C
Balotta
D000328:Adult; D019380:Anti-HIV Agents / Q000494:pharmacology*; D024882:Drug Resistance, Viral; D005260:Female; D005838:Genotype; D015658:HIV Infections / Q000453:epidemiology* / Q000635:transmission / Q000821:virology*; D015497:HIV-1 / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification*; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D020125:Mutation, Missense; D015995:Prevalence; D054302:pol Gene Products, Human Immunodeficiency Virus / Q000235:genetics
D019380:Anti-HIV Agents; D054302:pol Gene Products, Human Immunodeficiency Virus