World Journal of AIDS, 2013, 3, 192-196
http://dx.doi.org/10.4236/wja.2013.33025 Published Online September 2013 (http://www.scirp.org/journal/wja)
Laboratory Profile of HIV-2 and Dual HIV-1/HIV-2
Associated Acquired Immunodeficiency Syndrome
Georgina Njideka Odaibo#, David Olufemi Olaleye
Department of Virology, College of Medicine, University of Ibadan, University College Hospital, Ibadan, Nigeria.
Received June 21st, 2013; revised July 21st, 2013; accepted July 30th, 2013
Copyright © 2013 Georgina Njideka Odaibo, David Olufemi Olaleye. This is an open access article distributed under the Creative
Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original
work is properly cited.
Background: HIV-2 is comparatively less pathogenic with slow progression of infection to clinical disease and conse-
quently there is less of information on the occurrence of HIV-2 associated disease than HIV-1. We hereby describe
some laboratory profiles of individuals presenting with HIV-2 and dual HIV-1/2 related AIDS at the University College
hospital in Ibadan over a period of seven years. Methodology: Blood samples from patients presenting with the AIDS
defining illness at the University College Hospital, Ibadan, Nigeria were tested for antibodies to HIV-1/2 using rapid
test devices or ELISA. Initially reactive samples were further tested by immunoblotting for differentiation into HIV-1 or
HIV-2 or HIV-1/2 dual infection. Blood samples from individuals with confirmed infections were further analyzed for
CD4 cell lymphocyte number, plasma HIV-1 RNA concentration, hematological and blood chemistry parameters. The
data analysis was done using descriptive statistics and Levene-S test for equality of variance. Results: Thirty five pa-
tients, 18 and 17 with HIV-2 and dual HIV-1/2 infections respectively were identified during the period covered by this
study (2005-2012). The median age of the patients was 48 years old (Range: 42 - 70 years old) and mean CD4 cell
count of HIV-2 patien ts at enrollment was 324 (Range: 16 - 696) and 350 (Range 54 - 863) per microlitre of blood for
patients with dual HIV-1/2 infection. HIV-1 RNA was not detected in the plasma of the 18 patients with serological
HIV-2 infection but 2 (11.8%) of the 17 patients with dual HIV-1/2 serological profile had detectable HIV-1 RNA
(1,287,275 copies/ml and 1,816,491 copies/ml). Conclusion: The results emphasize the need to consider HIV-2 infec-
tion in the investigation of patients presenting with the AIDS related illness but with negative HIV-1serolo gy. The study
also shows the importance of inclusion of multispot HIV-1 and 2 rapid tests for differentiating HIV-1 from HIV-2 in-
fections in regions where both types of HIV circulate or epidemiologically indicated.
Keywords: HIV-2; HIV1/2 Dual Infection; CD4; Hematology; Chemistry; Nigeria
One of the major complications and perhaps the most in-
teresting feature of the biology of the Human Immunode-
ficiency Virus (HIV) is the tremendous genetic diversity
of the virus. The high degree of diversity of HIV has im-
portant implications for host susceptibility, transmission,
pathogenesis, the diagnosis, susceptibility to antiretroviral
drugs and the design of vaccine against the virus among
others [1-3]. Presently, two types of the virus are known
to infect and cause disease in human, HIV-1 and HIV-2.
The HIV epidemic is characterized by the presence of
both types in West Africa, including Nigeria where HIV-
1 and HIV-2 infections have been reported at varying
proportions in different population groups over time [4-
6]. While HIV-1 has a high er propensity for variab ility with
subsequent evolution of several subtypes and circulating
recombinant forms [2,3], HIV-2 has been relatively sta-
ble with lower rate of transmission, less pathogenic, in-
fection progression of infection to clinical disease and li-
mited occurrence of HIV-2 associated disease [2,3,7-9].
*Competing interest: We declare that we have no conflicting interest in
the conduct of the study.
Authors’ contribution: GNO and DOO conceived the idea of the study,
GNO, DOO were involved in collection and analysis of data, GNO su-
ervised the laboratory investigations. GNO wrote the draft manuscript
while both authors reviewed the final manuscript and approved the final
version. DOO is the guarantor of the paper.
Copyright © 2013 SciRes. WJA
Laboratory Profile of HIV-2 and Dual HIV-1/HIV-2 Associated Acquired Immunodeficiency Syndrome in Nigeria 193
In Nigeria, the rate of occurrence of the two types of HIV
was about the same at the beginning of the epidemic [2,
4-6], but the relative rate of HIV-2 infection declined
over the years to less than 0.5% among infected persons
in different parts of the country . Consequently, at-
tention has not been placed on the differential diagnosis
of HIV-1 and HIV-2 and little or no preparation for the
management of HIV-2 related disease in West Africa
where circulation of the virus is predominant .
Scaling up of HIV prevention, treatment and care pro-
grammes started in 2002 in Nigeria with tremendous
success to date. The University College hospital in Iba-
dan is one of the reference centres in southwestern Nige-
ria where laboratory facilities are available for the dif-
ferential diagnosis of HIV-1 and HIV-2 infections, treat-
ment and monitoring, in addition to cytometry, HIV-1
RNA (viral load assay) and drug resistance testing. In this
publication, we describe the occurrence and some labo-
ratory profiles of individuals presenting with HIV-2 and
dual HIV-1/2 related Acquired Immunodeficiency Syn-
dromes (AIDS) at the University College hospital in Iba-
dan over a period of seven years.
2. Materials and Methods
2.1. Study Population and Samples
The study population consisted of three categories of in-
dividuals; persons presenting for VCT, pregnant women
participating in the PMCTC and patients referred for HIV
diagnoses from clinics and wards from within and outside
the University College hospital, Ibadan. Individuals in-
cluded were aged 18 years or older and were provided
with appropriate counseling for HIV testing. Those who
consented were tested for HIV-1 and HIV-2 infections,
informed of their serological status and referred for ap-
propriate care and management based on the protocol in
the Federal Ministry of Health of Nigeria approved HCT
and HIV treatment guidelines. The present study includ-
ed results of HIV tests that were carried out from January
2005 to December 2011.
2.2. Laboratory Methods
Combination HIV-1/HIV-2 screening tests using the al-
gorithm recommended by the Federal Ministry of Health
of Nigeria were used for this study. Initial combination
test for HIV-1/HIV-2 was performed and for any reactive
specimen, more specific testing to confirm the presence
of antibodies either to HIV-1 or HIV-2 was performed.
Rapid HIV screening procedures were performed at the
referring laboratories according to a serial testing algori-
thm with two distinct rapid HIV assays, the Determine
HIV-1/2 assay (Determine assay; Abbott Laboratories,
Abbott Park, Ill.) and STAT PAK HIV-1/HIV-2 assay. A
specimen was considered reactive if it tested positive for
HIV antibodies in a combination HIV-1/HIV-2 EIA or
rapid test device. Both tests are rapid test devices that are
based on the specific detection of anti-HIV-1 and anti-
HIV-2 antibodies by antigens that bind to the different
antibody binding sites. The resu lts are also interpreted vi-
sually as reactive or non-reactive.
Reactive specimens were further tested first, by West-
ern blot technique that detects and differentiate antibod-
ies to HIV-1 or HIV-2. In some cases, specimens that
were reactive by the combination HIV-1/HIV-2 test were
first tested by Western blot for HIV-1 only and those ne-
gative or indeterminate for HIV-1 antibodies were tested
again using HIV-2 Western blot assay (LAV Blot 2). In
both strategies, interpretation of the assays was based on
the recommendation of the manufacturers of the com-
mercial kits used.
All serological assays for differentiation between HIV-
1 and HIV-2 were carried out in the Department of Vi-
rology, University College hospital, Ibadan, Nigeria.
2.3. Laboratory Parameters and Analysis
Relevant demographic, clinical and blood specimens for
laboratory parameters on the patients were collected at
the time of enrolment and follow up visits. HIV related
disease staging at the time of enrolment was determined
using the CDC classification criteria. Laboratory profile
assessed included absolute CD4 cell count and HIV-1
plasma RNA, full blood count as well as blood urea,
creatinine, ALT and glucose levels. Data were analyzed
using descriptive statistics and Levene-S test for eq uality
A total of 35 patient presentin g with AIDS related illness
including 18HIV-2 and 17 dual HIV1/2 infection were
enrolled over a period of 7 years (2005-2012) covered by
this study. They included 14M, 4F for HIV-2 and 4M,
13F for HIV-2 and dual HIV-2 respectively. The median
age of the patients at enrolment was 48 years (Range: 42
- 70 years). The mean CD4 cell count of HIV-2 patients
at enrolment was 324 (Range: 16 - 696) and 350 (range
54 - 863) per microlitre of blood for patients with dual
HIV-1/2 infection (Table 1). The mean CD4 cell count
of HIV-2 infected male patients was higher than that of
the female but the reverse is the situation between mean
CD4 cell count of the male and female patients infected
with dual HIV-1/2 infection (Table 2). The other para-
meters were within the range of normal values. There
was no significant difference between the HIV-2 and HIV-
1/2 dually infected patients. Similarly, there was no sig-
nificant difference in the value of the parameters between
male and female patients in the two groups except in the
white blood cell counts th at was significantly higher (P =
0.02) among female than male patients dually infected
Copyright © 2013 SciRes. WJA
Laboratory Profile of HIV-2 and Dual HIV-1/HIV-2 Associated Acquired Immunodeficiency Syndrome in Nigeria
Copyright © 2013 SciRes. WJA
with HIV- 1 / 2 (Table 2).
The levelof blood urea among patients infected with
HIV-1/2 was significantly higher in those infected with
HIV-2 alone. In addition, the level of creatinine was hi-
gher than the normal value for the popu lation in the stud y
area. HIV-1 RNA was not detected in the plasma of the
18 patients with serological HIV-2 infection. On the
other hand, two (11.8%) of the 17 patients with dual
HIV-1/2 serological profile had detectable HIV-1 RNA
(1,287,275 copies/ml and 1,816,491 copies/ml) at pres-
entation. The value of each of the other blood parameters
analyzed in the samples of the patients is also shown in
Tables 1 and 2.
The relative low rate of HIV-2 and HIV-1/2 infection
compared to HIV-1 among patients that presented for
treatment in our facility in southwestern Nigeria over a
period of seven years covered by this study is in agree-
ment with previous reports on the declining rate of HIV-
2 and dual HIV-1/2 in the country since 1985 . How-
ever, it is significant to note that these individuals are
presented with AIDS defining clinical conditions which
emphasize the need to consider HIV-2 infection in pa-
tients with the clinical definition of AIDS but negative
HIV-1. These cases of HIV-2 related AIDS in our series
Table 1. Value of some laboratory parameters of persons presenting with HIV-2 and HIV-1/2 associated AIDS in Nigeria.
HIV-2 (N = 18) HIV 1/2 (N = 17)
S/N Parameter Normal range (Nigeria) Mean (±SD) Mean (±SD) P-value
1 CD4 365 - 1571 cells/ul 323.9 (213.6) 350.1 (251.5) 0.74
2 Urea 15 - 45 Mg/dL 19.0 (7.5) 36.3 (35.3) 0.05
3 WBC 4500 - 10,000 µL 4227.8 (1545.3) 3788.6 (1320.3) 0.34
4 ALT 12 - 40 IU/L 26.4 (22.6) 20.5 (11.7) 0.54
5 Creatinine 0.1 - 0.4 Mg/dL 0.9 (0.3) 1.1 (1.7) 0.99
6 Glucose 60 - 1 20 Mg/dL 89.6 (12.4) 88.1 (11.7) 0.40
7 Hemoglobin 10 - 14 g/dL 10.4 (2.5) 10.4 (2.3) 0.72
Table 2. Comparison by gender of some laboratory parameters of persons presenting with HIV-2 and HIV-1/2 associated
AIDS in Nigeria.
HIV-2 (N = 18) Male = 14, Female = 4 HIV 1/2 (N = 17) Male = 4, Female = 13
S/N Parameter Normal range (Nigeria) Mean (±SD) P-value Mean (±SD) P-value
1 CD4 male 351 - 1455 cells/ul 364.4 (219.0) 145.5 (47.6)
Female 385 - 1654 cells/ul 182.3 (128.3) 0.14 413.0 (256.0) 0.06
2 U rea male 19.4 (8.0) 43.0 (51.8)
Female 15 - 45 Mg/dL 17.8 (6.0) 0.72 34.2 (31.2) 0.68
3 WBC male 4000.0 (1547.2) 2476.5 (1653.0)
Female 4500 - 10,000 µL 5025.0 (1438.5) 0.25 4192.3 (943.8) 0.02
4 ALT male 29.1 (25.1) 21.5 (6.6)
Female 12 - 40 IU/L 16.8 ( 4.9) 0.35 20.2 (13.1) 0.85
5 Creatinine male 0.9 (0.3) 0.7 (0.2)
Female 0.1 - 0.4 Mg/dL 0.8 (0.3) 0.59 1.2 (1.9) 0.59
6 Glucose male 88.5 (13.2) 87.5 (9.6)
Female 60 - 120 Mg/dL 93.5 (9.4) 0.49 88.3 (12.6) 0.91
7 Hemoglobin male 10.5 (1.9) 9.6 (1.4)
Female 10 - 14 g/dL 10.3 (4.6) 0.90 10.7 (2.4) 0.40
Laboratory Profile of HIV-2 and Dual HIV-1/HIV-2 Associated Acquired Immunodeficiency Syndrome in Nigeria 195
call for urgent inclusion of multispot HIV-1 and 2 rapid
test for differentiating HIV-1 from HIV-2 infections in
settings where both types of HIV circulate or epidemio-
logically indicated. This approach will help to resolve
cases of HIV-2 associated AIDS in many African coun-
tries where the alternative strategy of the HIV diagnosis
of parallel or serial rapid test device is used due to the
high cost of immuno-blotting assays .
It is also worthy to note that the age ranges of the pa-
tients with HIV-2 and dual HIV-1/2 infections are diffe-
rent from that of HIV-1 infected persons in Nigeria [4-6,
10] and many other African countries [12-14]. While the
highest rate of HIV-1 infected persons remains the 19 -
24 years old in Nigeria, the age range of 40 - 72 years old
of persons infected with HIV-2 and dual HIV-1/2 in the
cohort reported in this paper lends credence to low trans-
missibility of HIV-2 . The data suggest that the indi-
viduals with HIV-2 related AIDS clinical condition s who
presented in our facility may have been infected several
years before progression to AIDS [4-6,15]. Previous re-
ports from the same region of the country showed that
rates of HIV-1 and HIV-2 infections were about the same
during the late 1980s and early 1990s [4-6] before a pro-
gressive decline in the relative rate of HIV-2 to HIV-1
infections to the current situation of less than 1% of HIV-
2 infection rate in the coun try .
The low mean CD4 cell count of the patients shows
that though infection may take a longer period, HIV-2
causes AIDS in infected persons thus the need for appro-
priate therapy cannot b e overe mphasized. The mean CD4
cell count of 324 (Range: 16 - 769) and 350 (Range: 54 -
863) of HIV-2 and HIV-1/2 infected patients respectively
in the cohort reported in this paper is lower than the re-
ported mean of CD4 cell count of healthy Nigerians .
Four (22.2%) out of the 18 patients with HIV-2 and 5
(29.4%) of the 17 patients with HIV-1 and 2 presented
with CD4 cell count less than 200/ul of blood. Based on
the current national guidelines for treatment of HIV/
AIDS in Nigeria  20 (57.1%) out of the 35 patients
described in this report presented with CD4 cell counts
below 350/ul of blood. This finding also indicates an ur-
gent need for inclusion of the protocol for a correct diag-
nosis and treatment of HIV-2 infected persons in the
treatment guidelines in West African countries and other
places where management of HIV-2 infection may be
epidemiologically indicated. It is also important that ref-
erence HIV laboratories are strengthened to carry out the
qualitative HIV-2 RNA assay for appropriate monitoring
of patients on antiretroviral therapy for HIV-2. Detection
of a high titre of plasma HIV-1 RNA in two of the 17 pa-
tients with dual HIV-2 and HIV-1 and 2 serological pro-
files is significant. There have been reports of the occur-
rence of dual HIV-1 and HIV-2 infections in the same in-
dividual [11,18] with suggestions of possibilities that
recombination events of HIV-1 and HIV-2 will o ccur 
and also the new variants of HIV [2,18]. The two patients
with detectable and high plasma HIV-1 RNA in this co-
hort also had very low CD4 cell co unts (97 and 54/ul re-
spectively). This situation suggests previous HIV-2 in-
fection that was superimposed with HIV-1 infection in
the acute phase just before presentation for AIDS relat-
ed care. As far as we can establish, this is the first de-
scription of HIV-2 associated AIDS from Nigeria.
What Is Already Known on This Subject
Previous reports have shown endemic presence and circulation of
HIV-2 in West Africa, including Nigeria. Studies have also shown a
low rate of transmission of HIV-2 and slow progression to clinical
disease relative to HIV-1.
What This Study Adds to Literature
The results of this study describe laboratory parameters in patients
presenting with HIV-2 and dual HIV-1/HIV-2 infection in settings
where both HIV-1 and HIV-2 co-circulate. Results of the study will
raise the index of suspicion among health care providers to consider
HIV-2 as a differential diagnosis in patients presenting with the
AIDS defining illness but with negative HIV-1 serology. The study
has also provided the much needed reference laboratory data for
proper management of HIV-2 associated AIDS in HIV-2 endemic
areas and other epidemiologically significant locations or situations.
The ART program at the University College Hospital is
supported by USG PEPFAR program through a Coop-
erative Agreement (No: 1U2GPS001058) from the Cen-
ters for Disease Control and Prevention. The content of
this article is solely the responsibility of the authors and
does not necessarily represent the official views of the
Centers for Disease Control and Prevention. We are grate-
ful to all the staffs of the ART clinic and Virology labo-
ratory for the patient enrollment and laboratory analysis.
We also appreciate our patients who participated in the
6. Ethical Considerations
Approval for the study was obtained from the University
of Ibadan/University College hospital ethical review board.
Informed consent was obtained from all participants in
 P. J. Kanki, “Biologic Features of HIV-2: An Update,”
AIDS Clinical Review, 1991, pp. 17-38.
 D. O. Olaleye, T. O. Harry and G. N. Odaibo, “The Viro-
logy and Dynamics of the Epidemic,” In: O. Adeyi, P. J.
Kanki, O. Odutolu and J. A. Idoko, Eds., AIDS in Nigeria:
A Nation on the Threshold, Harvard Center for Population
and Development, Cambridge, 2006, pp. 37-66.
Copyright © 2013 SciRes. WJA
Laboratory Profile of HIV-2 and Dual HIV-1/HIV-2 Associated Acquired Immunodeficiency Syndrome in Nigeria
 S. T. Meloni, A. Ojesina and D. O. Olaleye, “The Mole-
cular Epidemiology of HIV,” In: O. Adeyi, P. J. Kanki, O.
Odutolu and J. A. Idoko, Eds., AIDS in Nigeria: A Nation
on the Threshold, Harvard Center for Population and De-
velopment, Cambridge, 2006, pp. 67-92.
 D. Olaleye, L. Bernstein, C. Ekwezor et al., “Prevalence
of Human Immunodeficiency Virus Type 1 and 2 Infec-
tions in Nigeria,” The Journal of Infectious Diseases, Vol.
167, No. 3, 1993, pp. 710-714.
 J. Chikwen, I. Mohammed and O. T. Oyebode, “Preva-
lence of Human Immunodeficiency Virus (HIV) Infection
in Borno State of Nigeria,” East African Medical Journal,
Vol. 65, No. 5, 1988, pp. 342-346.
 T. Harry, O. Ekanna, J. Chikwen et al., “Seroepidemiolo-
gy of Human Immunodeficiency Virus Infection in Borno
State of Nigeria by Sentinel Sueveillance,” Journal of Ac -
quired Immune Deficiency Syndrome, Vol. 6, No. 1, 1993,
 S Jaffar, A. D. Grant, J. Whitworth, P. G. Smith and H.
Whittle, “The Natural History of HIV-1 and HIV-2 Infec-
tions in Adults in Africa: A Literature Review,” Bulletin
of World Health Organization, Vol. 82, No. 6, 2004, pp.
 A. G. Poulsen, P. Aaby, O. Larsen et al., “9-Year HIV-2 -
Associated Mortality in an Urban Community in Bissau,”
West African Lancet, Vol. 349, No. 9056, 1997, pp. 911-
 H. Whittle, J. Morris and J. Todd, T. Corrah, S. Sabally, J.
Bangali, P. T. Ngom, M. Rolfe and A. Wilkins, “HIV-2 In-
fected Patients Survive Longer than HIV-1-Infected Pa-
tients,” AIDS, Vol. 8, No. 11, 1994, pp. 1617-1620.
 Fedral Ministry of Health, “Nigeria; National HIV Sero-
Prevalence Sentinel Survey among Pregnant Women At-
tending Antenatal Clinics in Nigeria,” Technical Report,
2010, pp. 1-96.
 K. Peterson, S. Jallow, S. L. Rowland-Jones and T. I. de
Siliva, “Antiretroviral Therapy for HIV-2 Infection: Re-
commendations for Management in Low-Resource Set-
tings,” AIDS Research and Treatment, 2011, p. 13.
 A. S. Alabi, S. Jaffar, Ariyoshi et al., “Plasma Viral Load,
CD4 Cell Percentage, HLA and Survival of HIV-1, HIV-
2 and Dually Infected Gambian Patients,” AIDS, Vol. 17,
No. 10, 2003, pp. 1513-1520.
 S. Jallow, A. Alabi, R. Sarge-Njie et al., “Virological Re-
sponse to Highly Active Antiretroviral Therapy in Patients
Infected with Human Immunodeficiency Virus Type 2
(HIV-2) and Patients Dually Infected with HIV-1 and
HIV-2 in the Gambia and Emergence of Drug-Resistant
Variants,” Journal of Clinical Microbiology, Vol. 47, No.
7, 2009, pp. 2200-2208. doi:10.1128/JCM.01654-08
 P. J. Bock and D. M. Markovitz, “Infection with HIV-2,”
AIDS, Vol. 15, 2001, pp. S35-S45.
 N. K. Barry, S. Ariy oshi, S. Jaffar et al., “Low Peripheral
Blood Viral HIV-2 RNA in Individuals with High CD4
Percentage Differentiates HIV-2 from HIV-1 Infection,”
Journal of Human Virology, Vol. 1, 1998, pp. 457-468.
 D. K. Oladepo, E. O. Idigbe, R. O. Audu et al., “Establish-
ment of Reference CD4 and CD8 Lymphocyte Subsets in
Healthy Nigerian Adults,” Clinical and Vaccine Immuno-
logy, Vol. 16, No. 9, 2009, pp. 1374-1377.
 Federal Ministry of Health, “Abuja, Nigeria, National
Guidelines for HIV and AIDS Treatment and Care in
Adolescents and Adults,” pp. 1-67.
 T. de Siliva, C. van Tienen, S. Rowland-Jones and M. Cot-
ton, “Dual infection with HIV-1 and HIV-2: Double Trou-
ble or Destructive Interference?” HIV Therapy, Vol. 4,
No. 3, 2010, pp. 305-323. doi:10.2217/hiv.10.26
Copyright © 2013 SciRes. WJA