North American Big Brown Bats (Eptesicus fuscus) Harbor an Exogenous Deltaretrovirus.

Bats are the reservoir for a large number of zoonotic viruses, including members of Coronaviridae (severe acute respiratory syndrome coronavirus [SARS-CoV] and SARS-CoV-2), Paramyxoviridae (Hendra and Nipah viruses), Rhabdoviridae (rabies virus), and Filoviridae (Ebola virus) as exemplars. Many retroviruses, such as human immunodeficiency virus, are similarly zoonotic; however, only infectious exogenous gammaretroviruses have recently been identified in bats. Here, viral metagenomic sequencing of samples from bats submitted for rabies virus testing, largely due to human exposure, identified a novel, highly divergent exogenous Deltaretrovirus from a big brown bat (Eptesicus fuscus) in South Dakota. The virus sequence, corresponding to Eptesicus fuscus deltaretrovirus (EfDRV), comprised a nearly complete coding region comprised of canonical 5'-gag-pro-pol-env-3' genes with 37% to 51% identity to human T-lymphotropic virus (HTLV), an infectious retrovirus that causes T-cell lymphoma. A putative tax gene with 27% identity to HTLV was located downstream of the pol gene along with a gene harbored in an alternative reading frame which possessed a conserved domain for an Epstein-Barr virus nuclear antigen involved in gene transactivation, suggesting a regulatory function similar to that of the deltaretrovirus rex gene. A TaqMan reverse transcriptase PCR (RT-PCR) targeting the pol gene identified 4/60 (6.7%) bats as positive for EfDRV, which, combined with a search of the E. fuscus genome that failed to identify sequences with homology to EfDRV, suggests that EfDRV is an infectious exogenous virus. As all known members of Deltaretrovirus can cause malignancies and E. fuscus is widely distributed in the Americas, often with a colonial roosting behavior in human dwellings, further studies are needed to investigate potential zoonosis.IMPORTANCE Bats host a large numbers of viruses, many of which are zoonotic. In the United States, the big brown bat (Eptesicus fuscus) is widely distributed and lives in small colonies that roost in cavities, often in human dwellings, leading to frequent human interaction. Viral metagenomic sequencing of samples from an E. fuscus bat submitted for rabies testing identified the first exogenous bat Deltaretrovirus The E. fuscus deltaretrovirus (EfDRV) genome consists of the typical deltaretrovial 5'-gag-pro-pol-env-3' genes along with genes encoding two putative transcriptional transactivator proteins distantly related to the Tax protein of human T-cell lymphotrophic virus and nuclear antigen 3B of Epstein-Barr virus. Searches of the E. fuscus genome sequence failed to identify endogenous EfDRV. RT-PCR targeting the EfDRV pol gene identified 4/60 (6.7%) bats with positive results. Together, these results suggest that EfDRV is exogenous. As all members of Deltaretrovirus are associated with T- and B-cell malignancies or neurologic disease, further studies on possible zoonosis are warranted.

Human oncoviruses: Mucocutaneous manifestations, pathogenesis, therapeutics, and prevention: Hepatitis viruses, human T-cell leukemia viruses, herpesviruses, and Epstein-Barr virus.

In 1964, the first human oncovirus, Epstein-Barr virus, was identified in Burkitt lymphoma cells. Since then, 6 other human oncoviruses have been identified: human papillomavirus, Merkel cell polyomavirus, hepatitis B and C viruses, human T-cell lymphotropic virus-1, and human herpesvirus-8. These viruses are causally linked to 12% of all cancers, many of which have mucocutaneous manifestations. In addition, oncoviruses are associated with multiple benign mucocutaneous diseases. Research regarding the pathogenic mechanisms of oncoviruses and virus-specific treatment and prevention is rapidly evolving. Preventative vaccines for human papillomavirus and hepatitis B virus are already available. This review discusses the mucocutaneous manifestations, pathogenesis, diagnosis, treatment, and prevention of oncovirus-related diseases. The first article in this continuing medical education series focuses on diseases associated with human papillomavirus and Merkel cell polyomavirus, while the second article in the series focuses on diseases associated with hepatitis B and C viruses, human T-cell lymphotropic virus-1, human herpesvirus-8, and Epstein-Barr virus.

A quantitative polymerase chain reaction test to enumerate leukocytes in allograft tissue and the implications for donor eligibility testing.

A country-to-country analysis of infectious disease screening requirements for donated tissues or cells reveals they are not often harmonized. Transmission of one such infectious disease, human T-lymphotropic virus (HTLV), is related to the transfer of HTLV-infected, viable leukocytes of sufficient number. The ability to characterize allograft tissue as being absent of leukocytes, or containing relatively few leukocytes, by using a specific test has not been previously investigated. A quantitative polymerase chain reaction (qPCR) test was developed to interrogate protein tyrosine phosphatase, receptor type C (PTPRC) gene expression in tissue samples and was able to determine the number of leukocytes present in a tissue. The impact of a qualified leukocyte tissue testing method should be significant and lead to changes in donor eligibility regulations in certain countries. Human leukapheresis samples were used as a control to establish the amount of PTPRC in leukocytes. That value was used as a comparator to determine the number of leukocyte equivalents in tissues of interest. The qPCR test measured tissue leukocyte equivalents and the results were consistent with the relative abundance of leukocytes predicted for each tissue. Using qPCR to calculate leukocyte equivalents based upon PTPRC gene expression can be successfully employed to estimate the number of leukocytes in a tissue or allograft. This method could be used as a screen to rule out tissues that do not meet the criteria of being leukocyte rich and, therefore, do not need direct HTLV testing.

Human T-lymphotropic virus lookback in NHS Blood and Transplant (England) reveals the efficacy of leukoreduction.

BACKGROUND: Leukoreduction of blood components was introduced in the United Kingdom during 1998. Human T-lymphotropic virus (HTLV) screening of blood donations was introduced in 2002. NHS Blood and Transplant conducted an HTLV lookback on blood components issued before 2002. A proportion of included components were nonleukoreduced, although the majority were subject to white blood cell reduction measures. STUDY DESIGN AND METHODS: A standard lookback was conducted on untested cellular blood components from donors later confirmed to be HTLV positive, for the 4 to 5 years before 2002, and on the last tested negative donation from donors who had seroconverted. RESULTS: A total of 437 red blood cell and platelet components were included and an outcome was reported for 84% of these. Just over half of identified recipients were dead at the time of lookback; blood samples for testing were obtained from 77% of identified living recipients. HTLV infection was confirmed in seven recipients, but one was discounted as not transfusion transmitted. CONCLUSION: Although numbers are small, our results provide evidence of the efficacy of leukoreduction in reducing the likelihood of HTLV transmission through transfusion of cellular blood components. The HTLV-positive rate in recipients of leukoreduced components was 3.7%, a reduction of 93% compared with nonleukoreduced components. Importantly, the one infected recipient of a leukoreduced component had existing risk factors for HTLV infection. HTLV lookback was much less efficient in identifying infected recipients than was hepatitis virus C lookback.

Recruiting individuals into the HTLV cohort study in the United Kingdom: clinical findings and challenges in the first six years, 2003 to 2009.

Human T-lymphotropic virus (HTLV) infection is rare in the United Kingdom (UK) and few studies are available worldwide. Following introduction of blood donation testing in 2002, a cohort of individuals could be identified and prospectively recruited to describe progression and onset of disease. Here we describe baseline characteristics of participants, and evaluate recruitment into the UK HTLV National Register over the first six years, from July 2003 to June 2009. A multicentre cohort study recruited participants from the UK blood services (recipients and donors) and specialist HTLV clinics. Almost half of the 148 participants recruited were blood donors, nine were blood transfusion recipients, 40 contacts and 29 clinic attendees (nine asymptomatic and 20 symptomatic). Most participants were HTLV-1 positive (n=115); 11 had HTLV-2 and 22 were HTLV-negative. Baseline self-completion questionnaires were received for 83%. The most commonly reported condition was a past operation/serious illness (69%). Twenty-six participants reported four or more possible signs/symptoms of HTLV-1-associated myelopathy/tropical spastic paraparesis. Recruitment into a study of a rare, long-term infection is challenging. This cohort will enable descriptions of HTLV-associated disease progression amongst people recruited from varying sources; it is the first prospective study of its kind in Europe.

Short communication: no evidence of HTLV-3 and HTLV-4 infection in New York State subjects at risk for retroviral infection.

The primate T-cell lymphoma viruses (PTLV) are divided into six distinct species. The biology and epidemiology of PTLV-1 and PTLV-2 are very well understood. However, that of PTLV-3, 4, 5, and 6 are not. Recently, in Cameroon, three and one humans were shown to be infected with HTLV-3 and HTLV-4, respectively. We undertook a study to ascertain whether any of these two retroviruses were present in the peripheral blood mononuclear cell DNA of New York State subjects deemed at risk for PTLV infection. Samples were analyzed by PTLV-3 and PTLV-4 specific PCR assays from the following human and simian subject types: African-American medical clinic patients; HTLV EIA+, WB indeterminate blood donors; intravenous drug users; patients with leukemia, lymphoma, myelopathy, polymyositis, or AIDS; and African chimpanzees. None of the 1200 subjects was positive for HTLV-3 or 4. The data indicate that, at the time of sample collection, no evidence exists for the dissemination of HTLV-3 or 4 to New York State. Continued epidemiological studies are warranted to explore the worldwide prevalence rates and dissemination patterns of HTLV-3 and 4 infections, and their possible disease associations.

Discovery and significance of new human T-lymphotropic viruses: HTLV-3 and HTLV-4.

Human T-lymphotropic virus type 1 (HTLV-1) and type 2 (HTLV-2) were discovered approximately 30 years ago and they are associated with various lymphoproliferative and neurological diseases. The estimated number of infected people is 10-20 million worldwide. In 2005, two new HTLV-1/HTLV-2-related viruses were detected, HTLV-3 and HTLV-4, from the same geographical area of Africa. In the last 4 years, their complete genomic sequences were determined and some of their characteristic features were studied in detail. These newly discovered retroviruses alongside their human (HTLV-1 and -2) and animal relatives (simian T-lymphotropic virus type 1-3) are reviewed. The potential risks associated with these viruses and the potential antiretroviral therapies are also discussed.

New strain of human T lymphotropic virus (HTLV) type 3 in a Pygmy from Cameroon with peculiar HTLV serologic results.

A search for human T lymphotropic virus (HTLV) types 1 and 2 and related viruses was performed by serological and molecular means on samples obtained from 421 adult villagers from the southern Cameroon forest areas. One individual (a 56-year-old Baka Pygmy hunter) was found to be HTLV-3 infected; however, there was a low proviral load in blood cells. Complete sequence analysis of this virus (HTLV-3Lobak18) indicated a close relationship to human HTLV-3Pyl43 and simian STLV-3CTO604 strains. Plasma samples from Lobak18, the HTLV-3 infected individual, exhibited a peculiar "HTLV-2-like" pattern on Western blot analysis and were serologically untypeable by line immunoassay. These results were different from those for the 2 previously reported HTLV-3 strains, raising questions about serological confirmation of infection with such retroviruses.

No genetic evidence for involvement of Deltaretroviruses in adult patients with precursor and mature T-cell neoplasms.

BACKGROUND: The Deltaretrovirus genus comprises viruses that infect humans (HTLV), various simian species (STLV) and cattle (BLV). HTLV-I is the main causative agent in adult T-cell leukemia in endemic areas and some of the simian T-cell lymphotropic viruses have been implicated in the induction of malignant lymphomas in their hosts. BLV causes enzootic bovine leukosis in infected cattle or sheep. During the past few years several new Deltaretrovirus isolates have been described in various primate species. Two new HTLV-like viruses in humans have recently been identified and provisionally termed HTLV-III and HTLV-IV. In order to identify a broad spectrum of Deltaretroviruses by a single PCR approach we have established a novel consensus PCR based on nucleotide sequence data obtained from 42 complete virus isolates (HTLV-I/-II, STLV-I/-II/-III, BLV). The primer sequences were based on highly interspecies-conserved virus genome regions. We used this PCR to detect Deltaretroviruses in samples from adult patients with a variety of rare T-cell neoplasms in Germany. RESULTS: The sensitivity of the consensus PCR was at least between 10-2 and 10-3 with 100% specificity as demonstrated by serial dilutions of cell lines infected with either HTLV-I, HTLV-II or BLV. Fifty acute T-cell lymphoblastic leukemia (T-ALL) samples and 33 samples from patients with various rare mature T-cell neoplasms (T-PLL, Sézary syndrome and other T-NHL) were subsequently investigated. There were no cases with HTLV-I, HTLV-II or any other Deltaretroviruses. CONCLUSION: The results rule out a significant involvement of HTLV-I or HTLV-II in these disease entities and show that other related Deltaretroviruses are not likely to be involved. The newly established Deltaretrovirus PCR may be a useful tool for identifying new Deltaretroviruses.

Discovery of a new human T-cell lymphotropic virus (HTLV-3) in Central Africa.

Human T-cell Leukemia virus type 1 (HTLV-1) and type 2 (HTLV-2) are pathogenic retroviruses that infect humans and cause severe hematological and neurological diseases. Both viruses have simian counterparts (STLV-1 and STLV-2). STLV-3 belongs to a third group of lymphotropic viruses which infect numerous African monkeys species. Among 240 Cameroonian plasma tested for the presence of HTLV-1 and/or HTLV-2 antibodies, 48 scored positive by immunofluorescence. Among those, 27 had indeterminate western-blot pattern. PCR amplification of pol and tax regions, using HTLV-1, -2 and STLV-3 highly conserved primers, demonstrated the presence of a new human retrovirus in one DNA sample. tax (180 bp) and pol (318 bp) phylogenetic analyses demonstrated the strong relationships between the novel human strain (Pyl43) and STLV-3 isolates from Cameroon. The virus, that we tentatively named HTLV-3, originated from a 62 years old Bakola Pygmy living in a remote settlement in the rain forest of Southern Cameroon. The plasma was reactive on MT2 cells but was negative on C19 cells. The HTLV 2.4 western-blot exhibited a strong reactivity to p19 and a faint one to MTA-1. On the INNO-LIA strip, it reacted faintly with the generic p19 (I/II), but strongly to the generic gp46 (I/II) and to the specific HTLV-2 gp46. The molecular relationships between Pyl43 and STLV-3 are thus not paralleled by the serological results, as most of the STLV-3 infected monkeys have an "HTLV-2 like" WB pattern. In the context of the multiple interspecies transmissions which occurred in the past, and led to the present-day distribution of the PTLV-1, it is thus very tempting to speculate that this newly discovered human retrovirus HTLV-3 might be widespread, at least in the African continent.

A journey with T cells, primate/human retroviruses and other persisting human T-cell tropic viruses.

A study of the growth of primate/human T cells led to mechanisms for temporary laboratory culture of these cells (discovery of interleukin-2) and also their continuous culture (by immortalization after infection with human T-cell lymphotropic virus type 1 or 2 (HTLV-1 or 2)). Cultures of lymphocytes also led us to isolate five persisting T-tropic viruses: 1. the Hall's Island strain of gibbon ape leukemia virus, 2. HTLV-1, 3. HTLV-2, 4. human immunodeficiency virus and 5. human herpes virus-6 (HHV-6). This report is a brief synopsis of the discoveries of the first human retroviruses, the HTLV.

Current prevalence and incidence of infectious disease markers and estimated window-period risk in the American Red Cross blood donor population.

BACKGROUND: There has been continuing progress in measures to reduce the risk of transfusion-transmitted infection, including introduction of serologic tests of increased sensitivity and the recent implementation of investigational NAT in small pools of samples. STUDY DESIGN AND METHODS: Data relating to all blood donations to the American Red Cross have been consolidated into a single database. The prevalence of confirmed-positive test results for HBsAg, HCV, HIV, and HTLV were evaluated for each year for first-time donors from 1995 through 2001. Incidence rates for these infections were evaluated among repeat donors having at least two donations in a 2-year period. The frequencies of HIV-1 RNA- and HCV RNA-positive, seronegative donations were assessed for first-time and repeat donations. The relationship risk = (window period) x (incidence) was used to assess residual risk among repeat donations and to evaluate the incidence of HCV and HIV infection among first-time donors. RESULTS: During the study period, prevalence rates for all markers declined significantly over time: in 2001, the rates per 100,000 were 75.6 for HBsAg, 299 for HCV, 9.7 for HIV, and 9.6 for HTLV; the corresponding incidence rates (/100,000 person-years) were 1.267, 1.889, 1.554, and 0.239, respectively. Estimates of residual risk in donations from repeat donors (after NAT) for HCV and HIV were 1 per 1,935,000 and 1 per 2,135,000, respectively. However, incidence rates for these agents are approximately two times greater among first-time donors. For both HCV and HIV, NAT yield was concordant with that predicted by current window-period models. CONCLUSION: These data cover about half of all the whole blood collected in the United States. They suggest increasing improvement in transfusion safety and clearly define the benefit of pooled NAT.

Coinfection by Strongyloides stercoralis in blood donors infected with human T-cell leukemia/lymphoma virus type 1 in Sao Paulo city, Brazil

The frequency of coinfection with Strongyloides stercoralis and human T-cell leukemia/lymphoma virus type 1 (HTML-1) was determined in 91 blood donors examined at the blood bank of a large hospital in Sao Paulo city, Brazil. As control group 61 individuals, not infected by HTLV-1, were submitted to the same techniques for the diagnosis of S. stercoralis infection. In HTLV-1 infected patients the frequency of S. stercoralis infection was 12.1 percent; on the other hand, the control group showed a frequency significantly lower of S. stercoralis infection (1.6 percent), suggesting that HTLV-1 patients shoud be considered as a high risk group for strongyloidiasis in Sao Paulo city.

Human T-lymphotropic retrovirus type-1 in Thailand.

Seroprevalence of antibodies to human T-lymphotropic virus type-1 (HTLV-1) was surveyed among the Thai population by the particle agglutination test and Western blotting test. None of a total of 727 individuals from seven ethnic groups were positive for the specific antibody to HTLV-1. Among hospital based 3,427 subjects in Southern Thailand, one patient with a brain tumor showed positivity in the Western blotting test, however, HTLV-1 proviral genome was not identified by PCR. The present data suggest that HTLV-1 is not endemic in the Thai population and that HTLV-1 is not a major public health problem in Thailand because HTLV-1 rarely causes its associated diseases.

Transfusion virology: progress and challenges.

Discoveries of new human viruses and new technologies for their detection have made, and will continue to make, major contributions to the safety of blood transfusion. This article discusses the practical issues involved in the implementation of additional serological screening tests for viruses such as human T-lymphotropic virus, and reviews current information on the prevalence and pathogenicity of more recently discovered viruses, such as hepatitis G virus (HGV) or GB virus-C (GBV-C) and human herpes virus 8, a potential aetiological agent of Kaposi's sarcoma. Progress in the technology behind nucleic acid amplification techniques, such as the polymerase chain reaction (PCR), makes direct detection of viruses such as human immunodeficiency virus and hepatitis C virus possible. The use of such methods for screening will allow the earlier detection of acutely-infected individuals and the elimination of transmission from 'window' period donations before seroconversion for antibody. Establishing a framework for PCR-based screening would also enable the testing for others such as hepatitis A virus, parvovirus B19 and GBV-C/HGV for which serological detection methods cannot be or have not been developed.

HTLV testing in blood transfusion.

To improve the safety of the blood supply, HTLV screening of blood donations became mandatory in different countries. In Japan and in Europe, the majority of HTLV-infected donors are HTLV-1 whereas in the USA more than half of them are HTLV-II-positive. The prevalence of HTLV-infected donors is low in European Countries as is the rate of seroconversion. Consequently, to test donors only once would have a high efficiency. This procedure is already in use in certain countries. Furthermore, if the use of leucodepleted cell concentrates is generalized, the policies of HTLV screening will still be further modified.

Vertical transmission of HTLV-I/II: a review

A transmissao vertical do virus linfotropico para celulas T humanas tipo I (HTLV) ocorre principalmente atraves da amamentacao. Como um pequeno percentual de filhos de portadoras alimentados artificialmente e soropositivo, devem existir outras vias de transmissao vertical. A taxa de prevalencia de transmissao vertical no Japao varia de 15 por cento a 25 por cento. No Brasil, ainda nao existe nenhuma avaliacao desta forma de transmissao, no entanto, sabe-se que em Salvador-Bahia 0,7 por cento a 0,9 por cento das gestantes de classe socio-economica baixa sao portadoras