Molecular characterization of human T-cell lymphotropic virus type 2 (HTLV-II) from people living in urban areas of Sao Paulo city: evidence of multiple subtypes circulation.
BACKGROUND
In Brazil, human T-cell lymphotropic virus type I and type II (HTLV-I and HTLV-II) are co-circulating and possess approximately 65% homology, which results in high cross-reactivity in serological tests. Based on the detection of EIA and Western blot (WB) tests, HTLV serodiagnosis yields indeterminate results in high-risk population, with the true determination of HTLV-II prevalence requiring a combined serological and molecular analysis. Molecular analysis of HTLV-II isolates has shown the existence of four distinct subtypes: IIa, IIb, IIc, and IId. The aim of this study was to evaluate the routine EIA and WB used in Sao Paulo city, as well as molecular methods for confirmation of infection and HTLV-II subtype distribution.


RESULTS
Two hundred ninety-three individuals, who were enrolled in the HTLV out-clinic in Sao Paulo city, Brazil, between July 1997 and May 2003, were tested by EIAs, and positive sera 232 (79%) reactive by one of the tests. When these sera were tested by WB revealed 134 were HTLV-I, 28 HTLV-II, 4 HTLV-I/II, and 48 were indeterminate. Polymerase chain reaction (PCR) on the indeterminate group showed that 20 (42%) were HTLV-II and 28 were negative. From a total of 48 HTLV-II subjects with DNA available, restriction fragment length polymorphism (RFLP) of the env region revealed 47 HTLV-IIa and 1 HTLV-IIb. The phylogenetic analysis was performed on 23 samples, which identified 19 as subtype a, Brazilian subcluster, and 4 as subtype b. This is the first time HTLV-II subtype b has been described in Brazil. However, further studies, such as a complete nucleotide DNA sequencing, need to be done to confirm these findings.
Novoa
Patricia
P
Institute of Infectious Diseases Emilio Ribas, Sao Paulo, Brazil.
Penalva de Oliveira
Augusto César
AC
Posada Vergara
Maria Paulina
MP
da Silva Duarte
Alberto José
AJ
Casseb
Jorge
J
D000328:Adult; D015153:Blotting, Western; D001938:Brazil / Q000453:epidemiology; D004279:DNA, Viral / Q000032:analysis; D005260:Female; D016356:Gene Products, tax / Q000235:genetics; D014644:Genetic Variation; D015482:HTLV-II Antibodies / Q000097:blood; D015491:HTLV-II Infections / Q000453:epidemiology* / Q000821:virology; D015367:Human T-lymphotropic virus 2 / Q000145:classification* / Q000235:genetics* / Q000276:immunology; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D015995:Prevalence; D015819:Substance Abuse, Intravenous / Q000150:complications
D004279:DNA, Viral; D016356:Gene Products, tax; D015482:HTLV-II Antibodies