The study was done to detect simultaneously the antigen and the antibodies in HIV patients attending the STD-OP of a tertiary care centre. A total of 114 patients were screened for HIV status. The regular protocol by NACO has detected only one case out 114 patients, whereas simultaneous detection of Ag and Ab by ELISA method has detected 2 more patients. This study highlights the necessity for using the newer generation kits in detecting new cases at the earliest and to reduce the window period.

1. Reduce the Window Period

2. Brief Report
Reduce the window period
Subbian Arunkumar a,
*, N. Thilakavathi b
, Adisesh Mangala b
, Rajagopal Vasanthi b
a
Department of STD, Chengalpattu Medical College, Chengalpattu, Tamilnadu, India
a
Institute of Venereology, Madras Medical College, Chennai, Tamil Nadu, India
a r t i c l e i n f o
Article history:
Received 7 March 2012
Accepted 8 May 2013
Available online 7 June 2013
Keywords:
HRG e High Risk Groups
HIV e human immunodeficiency
virus
Fourth generation HIV kit
a b s t r a c t
The study was done to detect simultaneously the antigen and the antibodies in HIV pa-
tients attending the STD-OP of a tertiary care centre. A total of 114 patients were screened
for HIV status. The regular protocol by NACO has detected only one case out 114 patients,
whereas simultaneous detection of Ag and Ab by ELISA method has detected 2 more pa-
tients. This study highlights the necessity for using the newer generation kits in detecting
new cases at the earliest and to reduce the window period.
Copyright ª 2013, Indraprastha Medical Corporation Ltd. All rights reserved.
1. Introduction
Worldwide HIV infection is estimated in more than 33 million
people and there are an estimated 2 million deaths per year
and there are about 2.7 million new HIV infections per year.
Approximately one-fourth of all HIV infections in adults
remain undiagnosed and that close to 60% of AIDS diagnosed
individuals discovered their seropositives at the diagnosis of
AIDS. Late diagnosis of HIV infection is associated with
increased mortality and morbidity and increased cost to
healthcare services.1
The diagnosis of primary infection
usually is achieved with standard antibody serologic tests.
The inclusion of P24 antigen assay can help to detect
HIV infection before the development of antibodies.
Advanced 4th generation assays can detect simultaneously
the P24 antigen and antibodies of HIV in serum. Usually we
do the tests to detect antibodies e the window period is 6e12
weeks. Here we are trying to reduce the window period
by performing the 4th Generation ELISA for HIV in the High
Risk Group (HRG) individuals attending the Institute of
Venereology (IOV).
2. Objectives
1) To decrease the window period in HRG patients attending
the IOV by using Advanced 4th Generation ELISA for HIV.
3. Materials and methods
HRG individuals attending the IOV with recent sexual expo-
sure were included into the study after getting the consent and
pre-test counselling. Blood sample was collected. All the
samples are tested for HIV both by the conventional method e
NACO protocol (Strategies III e 2007)2
and by 4th Generation
ELISA Kits (RFCL) using automated ELISA reader and washer.
The period of study was between 1st September to 5th
September 2009.
4. Results
Total number of patients tested 114: all are HRG patients.
Male e 74, Female e 40.
* Corresponding author. Tel.: þ91 9884166648.
E-mail address: arunssshc@gmail.com (S. Arunkumar).
Available online at www.sciencedirect.com
journal homepage: www.elsevier.com/locate/apme
a p o l l o m e d i c i n e 1 0 ( 2 0 1 3 ) 1 5 2 e1 5 4
0976-0016/$ e see front matter Copyright ª 2013, Indraprastha Medical Corporation Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.apme.2013.05.006

3. Results of the routine ELISA test
Results of the 4th Generation ELISA
5. Discussion
Antibody is detected in a majority of individuals within 6e12
weeks after infection with the present tests, but antibody
levels can be detected within 3e4 weeks after infection when
the newer third generation sandwich assays are used.3
This
window period can be further shortened to about 2 weeks
using p24 antigen assays or to 1 week further with imple-
mentation of nucleic acid detection assays.4
The detection of early infection has been shown to be
beneficial for the prompt initiation of appropriate antire-
troviral therapy in a clinically relevant time frame and an
evaluation reported that the time needed to diagnose acute
infection was shortened to approximately 2 weeks.5
Use of
nucleic acid testing and viral culture are highly sensitive
and specific methods to identify infection, respectively,
these procedures are time consuming, laborious and
expensive.6
HIV p24 antigenemia occurs early after infection; however,
when the antibodies become detectable, antigen is usually not
demonstrable, most likely because of antigen e antibody
complexes in the blood, thereby necessitating the test for HIV
antibody as well.7
The benefits of testing for both the antibody and antigen
are justifiable due to the need to identify individuals with
both established and early HIV infections not only within the
blood donor population but also in general population. Early
detection of infection via antigen testing promotes the
prompt referral of infected individuals for the initiation of
treatment, counselling, and prevention interventions to
reduce the risk of transmission.7
In our study we were able to
detect more patients by using the 4th generation ELISA test
for HIV.
Consequently, the window period between infection and
detection of infection may be reduced to 3 weeks if a
comprehensive testing approach is used.7
In addition to
increased sensitivity and specificity with the incorporation of
recombinant proteins and synthetic peptide antigens, these
4th Generation ELISA offers several advantages over other
types of assays in that it is inexpensive, relatively simple,
reproduceable, suitable for testing sizeable number of sam-
ples, and easily adopted to automated platforms.
By implementing antigen screening of blood, HIV in-
fections are prevented and lowering the risk of transmission
through blood transfusion in USA,8,9
organ transplantation,
mother to child transmission. Establishing the diagnosis in
discordant couples and medico legal cases.
A comparison of four of the commercial fourth genera-
tion assays versus four third generation antibody ELISAs
using seroconversion panels reported that all four of the
fourth generation assays detected infection in fewer days
than did all the third generation ELISAs, thus indicating
that these assays show promise in reducing the window
period by detecting early infection.10
The ability of this test
to enhance the diagnosis of those with acute HIV infection
will provide additional benefits in HIV prevention pro-
grammes and ultimately contribute to a reduction in the
spread of HIV.
Rapid 4th Generation tests are superior to 3rd generation
tests in detecting HIV antibody responses.11
6. Conclusion
Use of Advanced 4th Generation ELISA identified 2 patients
more while they are under seroconversion phase. Hence we
are in need of these advanced 4th generations ELISA kits to
detect the early HIV infection thereby preventing the trans-
mission of new infection. Prevention of new infection by 50%
is the goal by 2010, in the NACP 3, which can be achieved by
using this principle.
Conflicts of interest
All authors have none to declare.
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Positive Negative In determinant Total
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Positive Negative In determinant Total
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