Avaliação de dois testes sorológicos comerciais para diagnóstico das infecções pelo FIV e pelo FeLV / Evaluation of two point-of-care tests to diagnosis of FIV and FeLV infections

FIV e FeLV são retrovírus associados principalmente com neoplasias. Dois testes rápidos são disponibilizados no Brasil para o diagnóstico dessas infecções: um kit de imunocromatografia de fluxo bidirecional (SNAP® Combo IDEXX) e um kit de imunocromatografia de fluxo lateral unidirecional (ALERE/BIONOTE Anigen Rapid). O objetivo deste estudo foi comparar o teste SNAP® com o teste ALERE. Amostras de sangue de 178 gatos foram testadas utilizando-se ambos os kits. A reação em cadeia de polimerase em tempo real (qPCR) foi empregada como método confirmatório para todos os resultados. O teste SNAP® apresentou sensibilidade e especificidade de 100% para FIV; a sensibilidade e a especificidade do teste ALERE foram de 96,15% e 98,68%, respectivamente. A sensibilidade e a especificidade para o FeLV foram de 93,02% e 96,30% para o teste SNAP® e de 90,70% e 97,78% para o teste ALERE. Ainda em relação ao FeLV, três amostras com resultado positivo na qPCR obtiveram resultado falso-negativo em ambos os testes. Não houve diferença estatisticamente significante entre os métodos. Considerando a qPCR como padrão-ouro, o teste SNAP® apresentou maior sensibilidade e especificidade para o FIV, e o teste ALERE apresentou maior especificidade para o FeLV. Os resultados mostraram uma boa correlação entre os testes.(AU)

FIV and FeLV are Retrovirus associated mainly with feline neoplasms. Two point-of-care tests are commercially available in Brazil for diagnosis of these infections: a bidirectional flow immunochromatography kit (IDEXX SNAP ® Combo) and a lateral unidirectional flow immunochromatography kit (ALERE/BIONOTE Anigen Rapid). The aim of this study was to compare SNAP ® and ALERE tests. Blood samples obtained from 178 cats were evaluated using both tests. Quantitative real-time polymerase chain reaction (qPCR) was used as confirmatory test for all samples. The sensitivity and specificity of SNAP ® test was 100% for FIV, and for ALERE test was 96.15% and 98.68%, respectively. The sensitivity and specificity for FeLV was 93.02% and 96.30% for SNAP ® test and 90.70% and 97.78% for ALERE test. Three samples with a qPCR positive result for FeLV obtained a false negative result in both SNAP ® and ALERE tests. There was no statistically significant difference between the two methods. Considering qPCR as gold standard method, the SNAP® test showed higher sensitivity and specificity for FIV, and the ALERE test presented higher specificity for FeLV. The results showed good agreement among the tests.(AU)

Virus emergentes de importancia en medicina transfusional: paradigmas, hitos, aprendizajes / Emergent virus with importance in transfusional medicine: paradigms, milestones, learnings

Las infecciones emergentes juegan un papel importantísimo en medicina transfusional. La experiencia con HIV puso en evidencia la necesidad de actuar rápidamente. La lentitud en la respuesta de los Bancos de Sangre y la falta de un liderazgo en la adopción de medidas preventivas dieron lugar a una transmisión importante por vía transfusional. En cuanto a las hepatitis postransfusionales NANB, aprendimos las lecciones acerca de las pruebas subrogantes. Sin embargo, la respuesta para prevenir la transmisión de HCV fue lenta porque la comunidad científica estaba focalizada en la transmisión de HIV. En el caso del XMRV, la presión ejercida por la comunidad fue muy importante. Se formaron grupos multidisciplinarios de expertos que realizaron gran cantidad de estudios y la respuesta ocurrió rápidamente, aunque al poco tiempo se demostró que este patógeno no era relevante para la Medicina Transfusional. Con respecto al WNV, la familiaridad con los modelos desarrollados por el CDC para estimar los riesgos y las lecciones aprendidas por las experiencias con HIV y HCV facilitaron una respuesta rápida y se implementaron medidas rápidamente para minimizar el riesgo de transmisión por vía transfusional. Se abrió un nuevo paradigma: la importancia de considerar los riesgos de transfusión que pueden derivar de agentes que causan viremias breves, usualmente asintomáticas, pero con el potencial de generar brotes estacionales de alta incidencia. La respuesta a la amenaza con WNV fue rápida, apropiada y exitosa. Las nuevas herramientas de biología molecular han permitido el aislamiento de numerosos gérmenes emergentes y lo seguirán haciendo en el futuro. Estar alertas ante nuevos patógenos de potencial importancia es nuestra responsabilidad.

Emerging infections play an extremely important role in transfusion medicine. Experience with HIV highlighted the necessity to act quickly. The slow Blood Banks response and the lack of leadership in the adoption of preventive measures resulted in a significant transfusional transmission. Regarding the post-transfusion NANB hepatitis, we have learned the lessons about the surrogate tests. However, the response to prevent HCV transmission was slow given that the scientific community was focused on HIV transmission. In the case of XMRV, pressure from the community was extremely important. Multidisciplinary groups of experts who conducted many studies were formed and the answer came quickly, but soon it was proved that this pathogen was not relevant to Transfusion Medicine. With respect to WNV, familiarity with the models developed by the CDC to estimate the risks and lessons learned from experiences with HIV and HCV facilitated a quick response, and measures were quickly implemented to minimize the risk of transmission by transfusion. A new paradigm came up: the importance of con­sidering the risks of transfusion that may result from agents that cause brief, usually asymptomatic viremia, but with the potential to generate high incidence seasonal outbreaks of viralloads. The response to the threat with WNV was rapid, appropriate and successful. The new tools of molecular biology have allowed the isolation of many emerging germs and will continue to do so in the future. Being alert to new pathogens of potential importance is our responsibility.

Mouse mammary tumor virus (MMTV), a retrovirus that exploits the immune system. Genetics of susceptibility to MMTV infection

All animals, including humans, show differential susceptibility to infection with viruses. Study of the genetics of susceptibility or resistance to specific pathogens is most easily studied in inbred mice. We have been using mouse mammary tumor virus (MMTV), a retrovirus that causes mammary tumors in mice, to study virus/host interactions. These studies have focused on understanding the mechanisms that determine genetic susceptibility to MMTV-induced mammary tumors, the regulation of virus gene expression in vivo and how the virus is transmitted between different cell types. We have found that some endogenous MMTVs are only expressed in lymphoid tissue and that a single base pair change in the long terminal repeat of MMTV determines whether the virus is expressed in mammary gland. This expression in lymphoid cells is necessary for the infectious cycle of MMTV, and both T and B cells express and shed MMTV. Infected lymphocytes are required not only for the initial introduction of MMTV to the mammary gland, but also for virus spread at later times. Without this virus spread, mammary tumorigenesis is dramatically reduced. Mammary tumor incidence is also affected by the genetic background of the mouse and at least one gene that affects infection of both lymphocytes and mammary cells has not yet been identified. The results obtained from these studies will greatly increase our understanding of the genetic mechanisms that viruses use to infect their hosts and how genetic resistance to such viruses in the hosts occurs.

Superantígenos y retrovirus del tumor mamario murino / Superantigens and murine mammary tumor retrovirus

Hosts and their pathogens have co-evolved for millions of years, developing multiple and intimate interactions. Vertebrates have evolved a very complex immune system which pathogens have often been able to circumvent, in some cases even managing to appropriate some of its components for their own purpose. Among the pathogens which do use components of the immune system to survive and propagate, those coding for the expression of superantigens (SAgs) are now under intense scrutiny. Investigations concerning one of these pathogens, the mouse mammary tumor virus (MMTV), led to the understanding of how the expression of such components is a critical step in their life cycle. A number of milk-borne exogenous MMTV infect mice shortly after birth and, when expressed, produce superantigens. Herein, we describe the biological effects of new variants of MMTV. Two of these, BALB14 and BALB2 encoding SAgs with V beta 14+ and V beta 2+ specificities, respectively, were present in BALB/c mice of our colony (BALB/cT); a third variant, termed MMTV LA, originated in (BALB/cTxAKR)F1 mice from recombination between BALB 14 and Mtv-7 endogenous provirus. The recombinant LA virus induces the deletion of V beta 6+ and V beta 8.1+ T cells as a consequence of the acquisition of SAg hypervariable coding region of Mtv-7. The SAg encoded by MMTV LA strongly stimulates cognate T cells in vivo leading to a very effective amplification of lymphoid cells in BALB/c mice, correlating with a high incidence of mammary tumors. These results suggest that the presence of non-productive endogenous proviruses--generally considered to confer a selective advantage to the host by protecting it from infection with exogenous MMTVs encoding cross-reactive SAgs--could also be advantageous for the pathogen by increasing its variability, thus broadening the host range and allowing the expansion of highly tumorigenic variants.

Mouse mammary tumor virus (MMTV), a retrovirus that exploits the immune system. Genetics of susceptibility to MMTV infection

All animals, including humans, show differential susceptibility to infection with viruses. Study of the genetics of susceptibility or resistance to specific pathogens is most easily studied in inbred mice. We have been using mouse mammary tumor virus (MMTV), a retrovirus that causes mammary tumors in mice, to study virus/host interactions. These studies have focused on understanding the mechanisms that determine genetic susceptibility to MMTV-induced mammary tumors, the regulation of virus gene expression in vivo and how the virus is transmitted between different cell types. We have found that some endogenous MMTVs are only expressed in lymphoid tissue and that a single base pair change in the long terminal repeat of MMTV determines whether the virus is expressed in mammary gland. This expression in lymphoid cells is necessary for the infectious cycle of MMTV, and both T and B cells express and shed MMTV. Infected lymphocytes are required not only for the initial introduction of MMTV to the mammary gland, but also for virus spread at later times. Without this virus spread, mammary tumorigenesis is dramatically reduced. Mammary tumor incidence is also affected by the genetic background of the mouse and at least one gene that affects infection of both lymphocytes and mammary cells has not yet been identified. The results obtained from these studies will greatly increase our understanding of the genetic mechanisms that viruses use to infect their hosts and how genetic resistance to such viruses in the hosts occurs.

Carcinoma mamario murino transplantable (Ca.-MMT-INHRR-984): modelo biológico para el estudio de la oncogénesis viral / Transplantation muridae mammary (Ca.-MMT-INHRR-984): biological model to viral oncogenesis study

En este trabajo se describe la citología, histología y ultraestructura del tumor mamario transplantable (Ca-MMt-INHRR-984) de la cepa de ratones N: NIH (s) desarrollado a nivel intraperiritoneal y subcutáneo. Las células tumorales muestran cambios ultraestructurales relacionados con su actividad metabólica y se identificaron en el tejido signos de necrosis y degeneración en algunas células. Tanto en el tumor ascítico como en las células del tumor subcutáneo se vieron partículas virales correspodientes a retrovirus tipo B. Se discute la importancia de los hallazgos en relación con el conocimiento sobre la relación entre el MMTV y partículas similares detectadas en la leche y en las células del cáncer mamario humano, por lo que se plantea la utilidad del modelo biológico presentado para el estudio de la oncogénesis