Measuring the HIV viral load in the plasma can be useful for the determination of disease progression and treatment strategy (
23). The analogy between the results obtained from different assays is momentous, which can help to make the best decision for choosing the assay of analysis. CD4+ T-cells, the main targets of HIV infection, have a central role in orchestrating cellular immune reactions. These cells activate anti-HIV specific CD8+ T cells involved in viremia control (
24,
25). Measurement of the CD4+ T cell count is a standard method for the evaluation of HIV-infected patients because of the close correlation with the clinical manifestations of HIV infection. In our study, 75% of the subjects had co-infection with HBV and HCV; this high amount of co-infection seems to be associated with the sharing of syringes in drug abusers, as most of our patients were IVDUs. Hepatitis B virus and HCV infections are extremely common among HIV-infected patients because of their common transmission routes (
26,
27). The HCV infection causes an increase in the HIV/AIDS epidemic due to the facilitation of HIV progression (
28). However, the treatment of HIV with antiretroviral therapy (ART) in the HIV/HCV co-infected patients leads to a delay in the cirrhosis progression (
29).
The co-infection of HIV with HTLV-1 was lower (15%). However, these subjects were also drug abusers and had HBV and HCV infection too. It seems that the transmission rate of HTLV-1 is less than the HBV and HCV, as we have previously reported in the drug abusing prisoners in our endemic region (
2). Although HITLV-1 has the same prevalence as HBV and HCV in this region (
2) and despite the same route of transmission, the rate of HBV/HCV infection is higher (5 times) than HTLV-1 in HIV-infected patients. It is well-known that HTLV-1 is mainly transmitted from mother to neonate via breastfeeding. However, in any route of infection in vivo, HTLV-1 mainly transmitted through cell-cell contacts via a very specialized cell compartment called "virological synapse". Therefore, in contrast to HCV, HBV, and HIV, since there is no HTLV1 free version in body fluids, they are not infective. Human T-cell leukemia virus type-I and HIV as human retroviruses infect CD4+ T cells. There has been a direct relationship between HIV viral load and the clinical progression. Thus, high HIV viral load in HTLV-1 co-infection has been implicated in clinical progression and severity of AIDS (
4). Rahimi et al. in the northeast of Iran have shown that HIV viral load in HTLV-I/HIV co-infected subjects was higher than HIV-infected patients, and HTLV-I proviral load in HTLV-I/HIV co-infected subjects was lower than in HTLV-I infected patients. Therefore, the associations between HIV-HTLV-1 co-infection and clinical progression of HIV/HTLV-1 related diseases emphasize that in the endemic infected regions, more attention should be paid to these patients.
The present study showed a direct correlation between the results of the two common tests, including qRT-PCR and Cobas-Amplicor monitor test. Therefore, it was concluded that these techniques confirm each other. The phenotypic heterogeneity in clinical manifestations of the HIV-related symptoms and the duration of latency in a given population are surprisingly high. Hence, HIV-positive subjects travel the whole spectrum from carrying the healthy latent infection to opportunistic infections, and finally severe disease. The study revealed a considerable negative correlation between CD4+ count and the copy number obtained from the Cobas-Amplicor HIV monitor test. This outcome was expected as the CD4+ T cells are the main target of HIV. Therefore, their levels decrease in HIV-infected patients. However, this decrease was not detected by the application of qRT-PCR.
Although no correlation was found between the CD8+ count and the copy number, remarkable correlations were found between the CD4+/ CD8+ ratio and the two techniques. Therefore, this parameter can be considered more significantly to trace HIV infection. Since three-quarters of the HIV-infected patients were also infected by HBV and HCV due to sharing drug needles, this group of patients should be given more attention. The practical proceedings could include providing the syringe for drug users, increasing the education level, and facilitating access to health services. Moreover, the patients infected by one or two of the above-mentioned viruses should care more carefully because they probably have a high risk of infection from other viruses. The results of this study demonstrated that the HIV infection follow-up could be carried out by either the TaqMan RT-PCR or the Cobas-Amplicor HIV monitor test. However, the Cobas-Amplicor HIV monitor test is more reliable. Moreover, the CD4+/CD8+ ratio obtained by flow cytometry can confirm the results of the aforementioned two tests. Furthermore, there was a decreasing trend in the CD4+ level among subjects in stages 2 and 3. However, this specific trend was not observed among patients in Stages 1 and 4.
In the present study, the phylogenetic analysis showed that HIV-1 belonged to the AD genotype recombinant form of the M group, that is consistent with other studies from Iran. The first study by Naderi et al. on HIV-1 IVDUs positive subjects in 2005 demonstrated the presence of subtype A in Khorasan province (8). They suggested African origins, Uganda and Kenya, for the HIV circulating in this large region. However, the phylogenetic relationship findings in the present study showed radical changes to the CRF35-AD, which is the predominant subtypes in other parts of Iran (
22).
There are several important reasons for investigating genetic subtypes of HIV-1 circulating in an area. First, different subtypes express variant envelope proteins, and this is likely to affect vaccine development. For developing an effective vaccine, it is important to know geographically and/or subtype-specific strains (
30). Second, the genetic variation among subtypes can lead to problems in some detection methods (
31). Third, several studies have tried to correlate genetic variability to biological properties, such as transmission, disease prognosis, and response to treatment (
32-
34). For example, it has been suggested that HIV-1 subtype E, now recognized as CRF01-AE, may be more transmissible than subtype B in Thailand (
33,
35,
36). Fourth, knowledge about circulating subtypes is essential for understanding the epidemiology and spread of the HIV-1 pandemic (
37,
38).
5.1. Conclusions
One of the objectives of this study was to investigate the relationship between different subtypes circulating in Iran with the biological characteristics of the virus. Because only one subtype has been identified in this study, which is consistent with the results of previous studies in Iran, this aim is unattainable and requires a study with a larger number of samples.