Emerging infectious threats to the blood supply: seroepidemiological studies in iran - a review

Assessment of Torque Teno Virus (TTV) Frequency in Healthy Blood Donors in the Central Region of Iran, Yazd

Background: Torque teno virus (TTV) is a globally prevalent virus in humans, yet comprehensive knowledge about its prevalence, predominant transmission routes, and pathogenesis remains limited. This study aimed to assess the frequency of TTV infection among healthy blood donors in Yazd, Iran. Materials and Methods: A total of 236 healthy blood donors, devoid of HIV/HBV/HCV infection markers, participated in the study from 2015 to 2016. Nested Polymerase Chain Reaction (PCR) utilizing a set of oligo primers for the 5΄- UTR region was employed to detect TTV DNA in serum samples. Results: The TTV genome was identified in 161 out of 236 (61.2%) healthy blood donors. The mean age for men and women was 43 and 57 years, respectively. Of the participants, 156 were male, and 107 were female. Donor age exhibited a significant association with virus presence (P=0.007); however, gender did not show a statistically significant association with the frequency of TTV infection in healthy blood donors (P=0.3). Conclusion: The study revealed a notably high frequency of the Torque teno virus in Yazd province, aligning with similar findings globally. Further investigations are warranted to elucidate the clinical implications of the virus in the healthy population.

Trans-replicase helper activity of porcine circoviruses promotes the synergistic replication of torque teno virus

While the primary pathogenic potential of torque teno viruses (TTVs) is yet to be defined, TTVs are often co-detected with other pathogens and are suspected of exacerbating clinical disease in coinfections. Swine TTVs (TTSuVs) enhance clinical signs of porcine circovirus type 2 (PCV2) in a gnotobiotic pig model. However, the mechanisms involved are unknown. In this study, we observed that co-culture of TTSuV1 and PCV1, and specifically supplementing TTSuV1 cultures with the PCV replicase protein in trans consistently resulted in higher levels of replication of TTSuV1 when compared to TTSuV1 cultured alone. Therefore, the hypothesis that the PCV replicase (rep) protein has trans-replicase helper activity for TTSuV1 was examined. Based on EMSA and reporter gene assays, it was determined that the PCV1 rep directly interacted with the TTSuV1 UTR. The TTSuV1 rep trans-complemented a PCV rep null mutant virus, indicating that the TTSuV1 and PCV1 replicase proteins supported the replication of both viruses. In mice, the administration of plasmids encoding the PCV1 rep and a TTSuV1 infectious clone resulted in the production of higher TTSuV1 genome copies in dually exposed mice when compared to singly exposed mice. Higher sero-conversion and lymphoid hyperplasia were also observed in the dually exposed experimental mice. Thus, this study provides evidence for trans-replicase activity of PCVs and TTVs as a novel mechanism of explaining enhanced viral replication in coinfections involving both viruses.

The seroepidemiology and risk factors of West Nile virus infection in blood donors of Fars province, southwest of Iran

Aim: To evaluate the frequency of West Nile virus (WNV) in blood donors of the blood transfusion center of Fars province, Iran. Materials & methods: A total of 337 participants referred for blood donation to Fars blood centers were included. The presence of anti-WNV antibodies was analyzed using the WNV IgG ELISA kit. Results: Out of all participants, 76 (22.6%) were positive for anti-WNV IgG antibodies. Our results also showed that the frequency of WNV was associated with the age, educational level, job and city of residency of participants (p < 0.05). Conclusion: The results indicated the high frequency of WNV seropositivity among blood donors in southwest Iran. Accordingly, there is an urgent need to establish an integrated surveillance system for monitoring WNV infection in Iran.

Seroprevalence of human T-lymphotropic virus infection among blood donors in China: a first nationwide survey

Background

So far, the prevalence of human T-lymphotropic virus (HTLV) type 1 and 2 in some highly populated countries such as China is still unknown. In this study, a multi-center nationwide serological survey was designed and performed, to reveal the seroprevalence of HTLV infection among Chinese blood donors.

Results

Among 8,411,469 blood donors from 155 blood establishments, 435 were finally confirmed as HTLV carriers. The prevalence of HTLV infection in China varied in different provinces: Fujian had the highest prevalence of 36.240/100,000 (95% CI 31.990–41.050) and eleven provinces did not find HTLV-seropositive donors in the three years. no HTLV-2 infection was found. The overall prevalence of HTLV-1 in China decreased from 2016 to 2018. Female was identified as an independent risk factor of HTLV infection in China. Besides, seroconversion was observed in two of seven seroindeterminate donors 85 and 250 days after their last donation, respectively.

Conclusions

The seroprevalence of HTLV infection in most areas of China among blood donors is quite low, but it varies significantly in different geographic areas. Screening anti-HTLV-1/2 antibody and follow-up of serointederminate donors are essential to ensure blood safety especially in areas where we have found HTLV infected donors.

Torque teno viruses in health and disease

Torque teno viruses (TTVs) are small, ubiquitous, viruses with a highly diverse, single-stranded, negative sense DNA genome and wide host range. They are detected at high rates in both healthy and diseased individuals and are considered a significant part of the mammalian virome. Similar to human TTVs, swine TTVs (TTSuVs) are epidemiologically linked to several coinfections including porcine circovirus types 2 and 3 and the porcine reproductive and respiratory disease syndrome virus. Experimental infection of gnotobiotic pigs with TTSuVs resulted in lesions in multiple organs and exacerbation of coinfections, making TTSuVs the only members of the Anelloviridae family with experimental evidence for pathogenicity. However, due to the lack of reliable cell culture and animal models, mechanistic studies on viral immunity and pathogenesis are limited. The objective of this review is to summarize the current status of knowledge regarding the biology, detection, pathogenesis and public health significance of TTSuVs, while identifying gaps in knowledge which limit the field.

Seroprevalence and geographical distribution of human T-lymphotropic virus type 1 among volunteer blood donors in endemic areas of Iran

Background

Human T-cell lymphotrophic virus type 1 (HTLV-1) has a worldwide distribution and it is endemic in some regions of Iran. One of the most important routes of HTLV-1 transmission is via transfusion of contaminated blood components. The risk of transmission through asymptomatic blood donors, particularly in endemic areas should be considered and appropriately managed. The main objective of this study was to determine the seroprevalence and description the geographic distribution of HTLV-1 among voluntary blood donors in Iran.

Methods

This retrospective study carried out using the data obtained from the main database of the seven blood transfusion centers of Iranian Blood Transfusion Organization between 2009 and 2013. The presence of anti-HTLV-1/2 antibodies were primarily assessed using Enzyme-linked Immunosorbent Assay. The Ab Kit assay, contain antigens for the screening of antibodies to HTLV type 1 and 2. So, it is expressed as HTLV 1/2 assay. Samples that were positive by the western blot confirmatory test were considered as definite positive HTLV-1 or HTLV-2 cases. The main socio-demographic variables were; age, gender, donation history and marital status. Descriptive and analytical statistics were used to summarize the gathered data. The chi-Square Statistical test was used to test the association between groups, P-value of less than 0.05 was considered significant.

Results

A total of 1864489 blood donations were evaluated. There were 1840 confirmed HTLV-1 positive donations (0.098%). None were positive for anti-HTLV-2. The overall HTLV-1 prevalence was 98.7 per 100,000 donations during the 5 year period. Seroprevalence was higher among females, married and older blood donors. The overall seropositivity among first time, regular and lapsed donors was, 0.29% (290/100000), 0.001% (1/100000) and 0.02% (20/100000) respectively. A significant difference was observed between regular and the first time (p <0.0001) and also between lapsed and regular blood donors (p <0.0001). Most of the HTLV-1 seropositive blood donors (175 per 100,000) were from northeastern regions. We observed a gradual decline in overall HTLV-1 prevalence during the course of the study, the prevalence rate decreased from 0.13% (130/100000) in 2009 to 0.07% (70/100000) in 2013.

Conclusions

The Seroprevalence of HTLV-1 among Iranian blood donors in the regions of our study still is considerable, but there is an obvious declining prevalence over the course of present study. Blood transfusion centers should continually evaluate the residual risk of infection in the country, especially in endemic areas.

Prevalence of Toxoplasma gondii among Iranian Blood Donors: A Narrative Review Article

BACKGROUND

Toxoplasmosis is a common parasitic disease. There is likelihood of exposure to Toxoplasma gondii in blood donors during the periods of life. Currently, laboratory screening of blood donors for T. gondii is not routinely available. The objectives of this review were to study the effects of T. gondii on blood safety and to approach for risk reduction in blood recipients.

METHODS

A literature search was performed using Cochrane library, PubMed, Scopus, Google scholar IranMedex, SID and Magiran without time limitation. All studies, which had reported the prevalence of T. gondii in Iranian blood donors in both English and Farsi languages, were evaluated and reviewed. The contents of the transfusion medicine text books related to this issue were reviewed. Searching keywords were "Blood Donors" or "Blood Transfusion" and "Toxoplasma" or "Toxoplasmosis" and Iran.

RESULTS

In order to study the prevalence of T. gondii in Iranian blood donors, six studies have been reviewed. IgG and IgM antibodies varied between 12.3% to 52.8% and 0% to 5.47%. Some of these studies have suggested to doing the screening for all blood donors. However, based on parasitological and epidemiological evidences, there is little chance for parasite transmission by blood transfusion.

CONCLUSION

By considering the moderate prevalence, difficulty in the differentiation between recent and past infections, and cost-effectiveness, it is not possible and rational to perform screening of donated blood. To reduce the risk of parasite transmission, leukofilteration method is recommended.

Prevalence of Torque teno virus in healthy donors of Paraná State, southern Brazil

Objective

To determine the prevalence of the Torque teno virus in healthy donors in the northern and northwestern regions of the state of Paraná, southern Brazil.

Methods

The Torque teno virus was detected by a nested polymerase chain reaction using a set of oligoprimers for the N22 region.

Results

The prevalence of the virus was 69% in 551 healthy blood donors in southern Brazil. There was no statistically significant difference between the presence of the virus and the variables gender, ethnicity and marital status. There was significant difference in the prevalence of the virus regarding the age of the donors (p-value = 0.024) with a higher incidence (74.7%) in 18- to 24-year-old donors.

Conclusion

A high prevalence of Torque teno virus was observed in the population studied. Further studies are needed to elucidate the routes of contamination and the clinical implications of the virus in the healthy population.

Seroepidemiology of human T-cell lymphotropic virus among Iranian adult thalassemic patients

BACKGROUND

A large number of transfusion-dependent thalassemic patients is at a substantial risk for transfusion-transmitted infections. Human T-cell lymphotropic virus (HTLV) is a blood-borne pathogen and can be transmitted via cellular products. We aimed to evaluate the seroprevalence of HTLV in transfusion-dependent thalassemic patients referred to Tehran Adult Thalassemia Clinic.

METHODS

From 2008 to 2010, 257 transfusion-dependent thalassemic patients who referred to Tehran Adult Thalassemia Clinic were enrolled. The seroprevalence of HTLV, hepatitis B virus (HBV), hepatitis C virus (HCV), and HIV were assessed using enzyme-linked immunosorbant assay (ELISA). Also, the samples with positive result for anti-HTLVAb (by ELISA) were reassessed using Western blot for HTLV.

RESULTS

Among the 257 transfusion-dependent thalassemic patients who were tested for anti-HTLVAb, 29 (11.3%, 95% CI = 7.8-15.6%) were found to be anti-HTLVAb positive by ELISA and Western blot. No case was detected to be HBsAg positive, whereas 16% had HBV seroconversion criteria, and more than 95% had anti-HBsAb in their sera. Also, 103 (40.1%) patients were HCV seropositive, 13 (5.1%) patients of which were co-infected with HCV/HTLV. Among the HTLV-infected patients, 44.8% were co-infected with HCV, whereas 39.5% of HTLV-seronegative individuals were HCV mono-infected (P > 0.05).

CONCLUSION

This study showed that transfusion-dependent thalassemic patients were in higher risk for transmission of different blood-borne pathogens such as HTLV. The screening of HTLV in Iranian blood donors is recommended.