Durability of neutralizing antibodies and T-cell response post SARS-CoV-2 infection / 医学前沿

The ongoing pandemic of Coronavirus disease 19 (COVID-19) is caused by a newly discovered β Coronavirus named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). How long the adaptive immunity triggered by SARS-CoV-2 can last is of critical clinical relevance in assessing the probability of second infection and efficacy of vaccination. Here we examined, using ELISA, the IgG antibodies in serum specimens collected from 17 COVID-19 patients at 6-7 months after diagnosis and the results were compared to those from cases investigated 2 weeks to 2 months post-infection. All samples were positive for IgGs against the S- and N-proteins of SARS-CoV-2. Notably, 14 samples available at 6-7 months post-infection all showed significant neutralizing activities in a pseudovirus assay, with no difference in blocking the cell-entry of the 614D and 614G variants of SARS-CoV-2. Furthermore, in 10 blood samples from cases at 6-7 months post-infection used for memory T-cell tests, we found that interferon γ-producing CD4

TRIM35 mediates protection against influenza infection by activating TRAF3 and degrading viral PB2

Tripartite motif (TRIM) family proteins are important effectors of innate immunity against viral infections. Here we identified TRIM35 as a regulator of TRAF3 activation. Deficiency in or inhibition of TRIM35 suppressed the production of type I interferon (IFN) in response to viral infection. Trim35-deficient mice were more susceptible to influenza A virus (IAV) infection than were wild-type mice. TRIM35 promoted the RIG-I-mediated signaling by catalyzing Lys63-linked polyubiquitination of TRAF3 and the subsequent formation of a signaling complex with VISA and TBK1. IAV PB2 polymerase countered the innate antiviral immune response by impeding the Lys63-linked polyubiquitination and activation of TRAF3. TRIM35 mediated Lys48-linked polyubiquitination and proteasomal degradation of IAV PB2, thereby antagonizing its suppression of TRAF3 activation. Our in vitro and in vivo findings thus reveal novel roles of TRIM35, through catalyzing Lys63- or Lys48-linked polyubiquitination, in RIG-I antiviral immunity and mechanism of defense against IAV infection.

A glycoprotein E gene-deleted bovine herpesvirus 1 as a candidate vaccine strain

A bovine herpesvirus 1 (BoHV-1) defective in glycoprotein E (gE) was constructed from a Brazilian genital BoHV-1 isolate, by replacing the full gE coding region with the green fluorescent protein (GFP) gene for selection. Upon co-transfection of MDBK cells with genomic viral DNA plus the GFP-bearing gE-deletion plasmid, three fluorescent recombinant clones were obtained out of approximately 5000 viral plaques. Deletion of the gE gene and the presence of the GFP marker in the genome of recombinant viruses were confirmed by PCR. Despite forming smaller plaques, the BoHV-1△gE recombinants replicated in MDBK cells with similar kinetics and to similar titers to that of the parental virus (SV56/90), demonstrating that the gE deletion had no deleterious effects on replication efficacy in vitro. Thirteen calves inoculated intramuscularly with BoHV-1△gE developed virus neutralizing antibodies at day 42 post-infection (titers from 2 to 16), demonstrating the ability of the recombinant to replicate and to induce a serological response in vivo. Furthermore, the serological response induced by recombinant BoHV-1△gE could be differentiated from that induced by wild-type BoHV-1 by the use of an anti-gE antibody ELISA kit. Taken together, these results indicated the potential application of recombinant BoHV-1 △gE in vaccine formulations to prevent the losses caused by BoHV-1 infections while allowing for differentiation of vaccinated from naturally infected animals.

Interacción entre el virus de la inmunodeficiencia humana y el virus GB tipo-C durante el estado de co-infección / Interaction between HIV-1 and GB virus type-C during coinfection status

The human immunodeficiency virus (HIV) infection is one of the most important problems in public health. It is estimated that 3 3 million people are infected around the world. HIV and GBV-C share the same transmission route, being frequent the co-infection. Since both viruses replicate in CD4+ lymphocytes, recent studies have described an interaction. Decreasing of HIV viral load and higher CD4 counts have been observed in co-infected patients, leading a better clinical outcome. Nevertheless, some epidemiological studies have shown contradictory results. Additionally, in vitro models report inhibition of HIV by E1, E2, NS3 and NS5A GBV-C proteins, resulting in a decreasing of p24 antigen. This review summarizes the principal findings about co-infection and mechanisms that have been proposed for HIV-1 inhibition.

La infección por el virus de la inmunodeficiencia humana (VIH) continúa siendo uno de los principales problemas en salud pública; se estima que existen actualmente más de 33 millones de personas infectadas en el mundo. El VIH y el virus GB tipo C (GBV-C) comparten la misma vía de transmisión, por lo que es frecuente encontrar individuos co-infectados. Estudios recientes han descrito un efecto inhibitorio asociado a disminución en la carga viral de VIH, altos recuentos de CD4 y mayor tiempo de sobrevida en pacientes co-infectados, resultando en un mejor pronóstico y menor progreso a SIDA; adicionalmente, estudios in vitro indican que las proteínas virales E1, E2, NS3 y NS5A del GBV-C estarían implicadas en la inhibición del VIH-1. En el presente artículo se revisan los principales aspectos de la co-infección, y se describen los mecanismos propuestos para la inhibición de la replicación del VIH-1 mediada por las proteínas virales del GBV-C.

Desenvolvimento e validação de insumos para diagnóstico de infecções pelo vírus da dengue / Production and validation of diagnostic inputs for dengue virus infections

A dengue é uma doença causada por um flavivírus, representado por quatro sorotipos distintos (DENV1-4). Entre as proteínas virais, ENV e NS1 contribuem fortemente com o processo de resposta imune desencadeado pelo vírus. Os principais sistemas de diagnóstico utilizam a detecção de anticorpos através da técnica Enzyme Linked Immuno Sorbent Assay - ELISA, a qual, embora útil, apresenta inúmeras limitações (custo, tempo de processamento, entre outros). Neste trabalho, nós desenvolvemos ensaios multiplex de microarranjos líquidos para ENV e NS1. Sequências de aminoácidos codificantes das proteínas, provenientes de cepas isoladas da América Latina foram selecionadas em bancos de dados públicos, alinhadas para a geração das respectivas sequências consenso e construção dos antígenos recombinantes. As sequências obtidas foram otimizadas para expressão bacteriana, submetidas à síntese comercial e clonadas em vetores de expressão procarióticos. Os antígenos foram expressos e validados através de ensaios de microarranjos líquidos, com obtenção de promissores resultados, especialmente para as proteínas ENV (domínios I/II) sorotipo 1 e 2, com potencial aplicação comercial. Este trabalho desenvolveu ainda metodologia para renaturação de NS1 com excelente rendimento. Os resultados das proteínas produzidas neste trabalho foram de forma geral superiores aos obtidos por antígenos comercialmente disponíveis para a proteína ENV de dengue vírus, utilizando a mesma metodologia. As proteínas NS1 foram ainda utilizadas para imunização de coelhos e produção de anticorpos policlonais, que se mostraram bem sucedidos para aplicações em ensaios de imunofluorescência, western blot, citometria de fluxo e como anticorpo de detecção para ensaios quantitativos para a proteína NS1 por ELISA de captura. Os resultados obtidos neste projeto foram considerados extremamente promissores, com potencial aproveitamento no desenvolvimento de testes diagnósticos comerciais com alta precisão, rápidos e com baixo custo.

A bovine herpesvirus 5 recombinant defective in the thymidine kinase (TK) gene and a double mutant lacking TK and the glycoprotein E gene are fully attenuated for rabbits

Bovine herpesvirus 5 (BoHV-5), the agent of herpetic meningoencephalitis in cattle, is an important pathogen of cattle in South America and several efforts have been made to produce safer and more effective vaccines. In the present study, we investigated in rabbits the virulence of three recombinant viruses constructed from a neurovirulent Brazilian BoHV-5 strain (SV507/99). The recombinants are defective in glycoprotein E (BoHV-5gEÄ), thymidine kinase (BoHV-5TKÄ) and both proteins (BoHV-5gEÄTKÄ). Rabbits inoculated with the parental virus (N = 8) developed neurological disease and died or were euthanized in extremis between days 7 and 13 post-infection (pi). Infectivity was detected in several areas of their brains. Three of 8 rabbits inoculated with the recombinant BoHV-5gEÄ developed neurological signs between days 10 and 15 pi and were also euthanized. A more restricted virus distribution was detected in the brain of these animals. Rabbits inoculated with the recombinants BoHV-5TKÄ (N = 8) or BoHV-5gEÄTKÄ (N = 8) remained healthy throughout the experiment in spite of variable levels of virus replication in the nose. Dexamethasone (Dx) administration to rabbits inoculated with the three recombinants at day 42 pi did not result in viral reactivation, as demonstrated by absence of virus shedding and/or increase in virus neutralizing titers. Nevertheless, viral DNA was detected in the trigeminal ganglia or olfactory bulbs of all animals at day 28 post-Dx, demonstrating they were latently infected. These results show that recombinants BoHV-5TKÄ and BoHV-5gEÄTKÄ are attenuated for rabbits and constitute potential vaccine candidates upon the confirmation of this phenotype in cattle.

Viral complement regulators: the expert mimicking swindlers.

The complement system is a principal bastion of innate immunity designed to combat a myriad of existing as well as newly emerging pathogens. Since viruses are obligatory intracellular parasites, they are continuously exposed to host complement assault and, therefore, have imbibed various strategies to subvert it. One of them is molecular mimicry of the host complement regulators. Large DNA viruses such as pox and herpesviruses encode proteins that are structurally and functionally similar to human regulators of complement activation (RCA), a family of proteins that regulate complement. In this review, we have presented the structural and functional aspects of virally encoded RCA homologs (vRCA), in particular two highly studied vRCAs, vaccinia virus complement control protein (VCP) and Kaposi's sarcoma-associated herpesvirus complement regulator (kaposica). Importance of these evasion molecules in viral pathogenesis and their role beyond complement regulation are also discussed.

Coinfection with epstein barr virus in north Indian patients with HIV/AIDS.

Acquired immunodeficiency syndrome (AIDS) has emerged as a serious health problem in India. Although tuberculosis appears to be the commonest opportunistic infection, studies pertaining to opportunistic viruses are scant In the present study co infection with EBV was evaluated in patients with AIDS using a highly sensitive polymerase chain reaction besides anti Zebra antibody assays for diagnosis of an active EBV infection in 37 patients of full-blown AIDS and 32 healthy seropositives. Thirty healthy laboratory workers were used as controls. Out of 37 patients with AIDS, 12 were positive for anti Zebra antibodies and 23 were positive for EBV by the PCR reaction. Out of the 32 seropositives, 3 were positive for anti Zebra antibodies and 4 were positive by PCR assay. The difference between seropositives and AIDS was significant (p < .05). None of the controls were positive for an active EBV infection. It is concluded that active EBV infection is an important co infection in patients with AIDS and may contribute significantly to morbidity and mortality in these patients.

Antibody recognition of synthetic peptides mimicking immunodominant regions of HIV-1 p24 and p17 proteins / Reconocimiento por anticuerpos de péptidos sintéticos que imitan regiones inmunodominantes de las proteínas p24 y p17 de VIH-1

The gag gene of HIV-1 encodes a single open reading frame of 55 kDa that contains three subdomains: the matrix domain (p17), the capsid domain (p24) and the nucleocapsid domain (p15). The p24 and p17 proteins have a predominant a-helical structure and perform important functions throughout thevirallife-cycle. The determination of gag-specific antibodies is important because declining titers of these antibodies herald clinical deterioration.In this work we present the results obtained on immunoreactiviy of synthetic peptides that mimic immunogenic a-helical regions of p24 and p17. The influence on the immunoreactivity of structural modifications in native sequences, including the addition of non immunogenic side chains: AAAC- and -CAAA on both side of minimal epitopes was evaluated in indirect and competitive enzymeimmunoassays. The conformational characteristcs to the peptides were analysed by circular dichroism and these results were correlated with that obtained in the immunoassays. It was shown that the reactivity of peptides mimicking short a-helical regions of p24 and p17 is improved by adding short non immunogenic chains on both N- and C- terminus. These modifications enhanced the immobilization of the peptides onto the solid support and allowed more accesibility to the minimal epitopes byspecific antibodies, in solution.

El gen gag del VIH-1 codifica una región de 55kDA que contiene tres subdominios: matriz (p17), cápside (p24) y nucleocápside (p15). Las proteínas p24 y p17 tienen una estructura predominante helicoidal y cumplen un rol importante en el ciclo de vida del virus. En este trabajo presentamos los resultados de inmunorreactividad de péptidos sintéticos que imitan regiones helicoidales de p24 y p17. Utilizando enzimoinmunoensayos se evaluó la influencia de modificaciones en las secuencias nativas sobre la capacidad de reconocimiento de anticuerpos específicos en solución y en fase sólida, incluyendo el agregado de cadenas no inmunogénicas en ambos extremos de los epitopes mínimos. La conformación de los péptidos se determinó por dicroísmo circular y los resultados se correlacionaron con los de inmunorreactividad. Se observó que la capacidad de reconocimiento de anticuerpos por péptidos pequeños que imitan estructuras helicoidales de p24 y p17 mejoró con el agregado de cadenas no inmunogénicas en ambos extremos de los epitopes. Estas modificaciones mejoran la inmovilización sobre las superficies sólidas y permiten una mayor accesibilidad de los anticuerpos a los epitopes mínimos en solución.

The hepatitis C virus persistence: how to evade the immune system?

Hepatitis C virus (HCV) is an emerging virus of medical importance. A majority of HCV infections become chronic and lead to chronic hepatitis, liver cirrhosis and hepatocellular carcinoma. HCV usually induces robust immune responses, but it frequently escapes the immune defense to establish persistent infection. The fact that HCV exists as an evolving quasispecies plays an important role in the selection of escape mutants. Furthermore, several viral proteins interfere with cellular functions, in particular, those involved in the immune response of the host. Several HCV proteins also modulate cell signalling through interaction with different effectors involved in cell proliferation and apoptosis, or in the interferon-signalling pathway. In addition, HCV infects immune cells such as B and T cells, and thus affects their normal functions. These various strategies used by HCV to counter the immune response of the host are reviewed here. A better understanding of these mechanisms would help design new therapeutic targets.

Viral mimicry of the complement system.

The complement system is a potent innate immune mechanism consisting of cascades of proteins which are designed to fight against and annul intrusion of all the foreign pathogens. Although viruses are smaller in size and have relatively simple structure, they are not immune to complement attack. Thus, activation of the complement system can lead to neutralization of cell-free viruses, phagocytosis of C3b-coated viral particles, lysis of virus-infected cells, and generation of inflammatory and specific immune responses. However, to combat host responses and succeed as pathogens, viruses not only have developed/adopted mechanisms to control complement, but also have turned these interactions to their own advantage. Important examples include poxviruses, herpesviruses, retroviruses, paramyxoviruses and picornaviruses. In this review, we provide information on the various complement evasion strategies that viruses have developed to thwart the complement attack of the host. A special emphasis is given on the interactions between the viral proteins that are involved in molecular mimicry and the complement system.

Rotavirus bovino grupo A: diagnóstico y caracterización antigénica de cepas circulantes en la República Argentina, 1994-1999 / Group A bovine rotavirus: diagnosis and antigenic characterization of strains circulating in the Argentine Republic, 1994-1999

Group A Bovine Rotavirus (BRV) has been identified as a major cause of neonatal diarrhea in cattle. The study was aimed to determine the prevalence of BRV and to antigenically characterize the G-types of circulating strains in dairy and beef herds in Argentina. A total of 1129 stool samples from diarrheic calves was analyzed from 1994 to 1999. The samples were initially screened for RV by ELISA and PAGE, and then G-typed using monoclonal antibodies (Mab) directed against G1, G2, G3, G6 and G10-specific epitopes. Forty percent (452/1129) of the samples were positive for RV by ELISA, while 24.7 (279/1129) were also positive for PAGE. VP7 was detected in the 70.5 (319/452) of the positive samples using a broadly reactive Mab (C60); 32.6 (104/319) were G6, 15.4 (49/319) were G10, and 6 (19/319) were G1. However, 46.1 (147/319) of the samples remained untypable. Rotavirus diarrhea prevalences were comparable in beef and dairy herds (87.3 and a 74.4, respectively). Finally, G6 was the most prevalent G-type circulating in beef herds while G10 prevailed in dairy herds. A better understanding of RV epidemiology will contribute to the optimization of current vaccines and prevention programs of RV diarrhea in calves.

Lengua Azul. Actualización sobre el agente y la enfermedad / Blue tongue. Update on the agent and the disease

Bluetongue (BT) is a viral disease of domestic and wild ruminants. It is particularly damaging in sheep, where up to half of infected animals may die, showing inflammation and hemorrhages of the mucous membranes of the mouth, nose, and intestines. In cattle and goats, BT rarely causes disease, however it can affect the animal's reproductive ability, so that losses are not easily estimated. Bluetongue virus spreads from animal to animal by biting insects of the genus Culicoides; and this is the reason why the disease is more prevalent in geographic areas where climate conditions are favourable for their development. The disease was first recognized in South Africa in the late 1700's, but it was not until the early 1900's that it was described in detail, and at present, epizootiology and pathogenesis studies are still being carried on.

Sero-epidemiology of hepatitis E virus (HEV) in urban and rural children of North India.

OBJECTIVE: To estimate the prevalence of anti-HEV IgG and IgM antibodies to ORF3 peptide of Hepatitis E virus genome in an age stratified urban and rural population of children. DESIGN: Cross sectional survey. SETTING: Pediatric out-patient clinics in a tertiary hospital and a rural dispensary. METHODS: Study subjects between 6 months and 10 years with minor, non-hepatic illnesses were recruited for the study from March to December 1996. Baseline demographic details, drinking water source, sewage disposal methods, reasons for attending the hospital, histories of parenteral exposure in the past 12 months and acute hepatitis in the subjects and the family in the previous six months were obtained. Serum anti-HEV IgG antibodies were screened in all subjects, and in those who were positive, anti-HEV IgM antibodies were assayed as an indicator of recent infection. Serum aminotransferase (ALT) was estimated in those who were anti-HEV IgM antibody positive. RESULT: Out of 2160 subjects recruited, 2070 samples could be screened for anti-HEV IgG antibodies. In the urban population (n = 1065) anti-HEV IgG antibodies were detected in 306 subjects (28.7%; 95% CI 26.0-31.6) and of these 131 (42.8%; 95%CI 37.2-48.6) were anti-HEV IgM antibody positive. Amongst 1005 rural children, anti-HEV IgG antibodies were present in 239 (23.8%; 95% CI 21.1-26.4) and IgM antibodies in 113 (47.3%; 95% CI 40.9-53.7) children. The antibodies were present since the first year of age till 10 years of age and, increased with advancing age. Serum transaminases were raised in 7.5% (9/120) and 5.5% (5/88) of subjects with anti-HEV IgM antibodies in urban and rural centers respectively. Overall the seroprevalence of IgG antibodies against HEV were significantly more in urban as compared to that in rural subjects (p = 0.011). However, proportion of children with anti-HEV IgG carrying IgM antibodies was similar in the two study groups (p = 0.298). A model for estimating expected prevalence of anti-HEV IgG antibodies was developed. The observed antibody prevalence in both urban and rural subjects at each age interval after 48 months was less as compared to the expected levels and this gap increased with advancing age categories. It appeared that there was a decay of HEV antibodies with time. CONCLUSIONS: Children are susceptible to HEV infection since early infancy. The probability of exposure to HEV during childhood was higher in urban than rural population. Seropositivity to HEV antibodies increased by over 2 times beyond 4 years of age as compared to younger age. Anti-HEV IgG antibodies appear to wean off with increasing age.

Expresión de la proteína del gen supresor de tumores p53 en el carcinoma de próstata / Expression of the supressor gene protein of p53 tumors in prostatic carcinoma

El cáncer de la próstata es una de las neoplasias más frecuentes en hombres mayores de 50 años. La mutación y expresión del gen supresor de tumores p53 ha sido demostrado en la carcinogénesis de múltiples neoplasias y en alrededor del 40 por ciento de los cánceres de la próstata. El objeto de este trabajo es determinar la frecuencia de la expresión del gen p53 en el carcinoma prostático. Se estudia la expresión de la proteína p53 en 35 carcinomas prostáticos mediante la técnica de inmunohistoquímica con anticuerpo monoclonal. Los pacientes se distribuyeron por etapas clínicas: Etapa A = 4 casos; Etapa B = 5 casos; Gleason entre 4 y 7 y el 16 por ciento entre 8 y 10. El promedio de edad fue 70,7 años (límites 53-85 años). No se observó tinción positiva en ninguno de los controles ni en los tumores en etapas A y B. Se observó tinción positiva de la proteína del gen p53 en 11 de los 35 casos (31,4 por ciento), 17 por ciento en los en Etapa C y un 64,2 por ciento tumores en los en Etapa D (p = 0,01). No se observó diferencia respecto del índice de Gleason aun cuando los tumores mejor diferenciados presentaron menor positividad. Nuestros resultados muestran que la proteína del gen supresor de tumores p53 no guarda relación con el índice de Gleason y sólo se observa en tumores avanzados, especialmente en la Etapa D, y su determinación puede contribuir significativamente a una mejor evaluación preoperatoria de los pacientes

Fowlpox virus structural protein immunogens and characterization of single band polypeptide.

A fowlpox virus isolate obtained from an outbreak of disease in a vaccinated poultry flock was propagated in chicken embryo fibroblast cell culture. Analysis of purified virus polypeptide on 7.5-15% gradient polyacrylamide gel revealed 45 structural polypeptides after Coomassie blue staining. The mol.wt. of polypeptides ranged between 225.53 and 10.50 kDa with total mol.wt. of 2650 kDa. Variable numbers of immunogenic virion polypeptides were detected in immunoblot with fowlpox virus infected chicken sera collected at different time intervals. A total of 29 polypeptides reacted with sera collected at 1st week post-infection and the number gradually declined to 27, 26, 20, 17 and 15 when reacted with 2nd, 3rd, 4th, 5th and 6th week post-infection sera, respectively. Reaction with fowlpox virus hyperimmune sera revealed 35 immunogenic polypeptides. A number of major and minor immunogens were detected. Antisera against seven major single band polypeptides including one double band polypeptide showed very low reactivity both in ELISA and serum neutralization test. Involvement of multigenic components in virus neutralization is indicated.

Immunogenic activity of viral polypeptides of an Indian isolate of infectious bursal disease virus.

An Indian isolate of infectious bursal disease virus, i.e. IBDV-P/AD/81, was analysed for immunogenic activity of its structural polypeptides. Virus was purified from infected bursal homogenate by sucrose density gradient centrifugation. It showed five different structural polypeptides of 75.8, 45, 40.7, 33.1 and 27 kDa molecular weights in sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Anti infectious bursal disease virus (IBDV) antibodies were tested using enzyme-linked immunosorbent assay (ELISA) and neutralization test (NT). Polypeptide 40.7 kDa (VP2) was known to have neutralizing epitopes. However, polyclonal anti VP2 failed to neutralize the virus. It was interpreted that VP2 had labile neutralizing epitopes which get altered confirmationally by SDS. Surprisingly, polyclonal anti 33.1 kDa (VP3) had mild neutralizing activity.

Antibodies against non-structural c100/3 and structural core antigen of hepatitis C virus (HCV) in hemodialysis patients

Two groups of patients undergoing hemodialysis (HD) maintenance were evaluated for their antibody response to non-structural c100/3 protein and structural core protein of hepatitis C virus (HCV). Forty-six patients (Group 1) never presented liver abnormalities during HD treatment, while 52 patients (Group 2) had either current or prior liver enzyme elevations. Prevalence rates of 32.6 and 41.3 were found for anti-c100/3 and anti-HCV core antibodies, respectively, in patients with silent infections (Group 1). The rate of anti-c100/3 in patients of Group 2 was 71.15 and reached 86.5 for anti-HCV core antibodies. The recognition of anti-c100/3 and anti-core antibodies was significantly higher in Group 2 than in Group 1. A line immunoassay composed of structural and non-structural peptides was used as a confirmation assay. HBV infection, measured by the presence of anti-HBc antibodies, was observed in 39.8 of the patients. Six were HBsAg chronic carriers and 13 had naturally acquired anti-HBs antibodies. The duration of HD treatment was correlated with anti-HCV positivity. A high prevalence of 96.7 (Group 2) was found in patients who underwent more than 5 years of treatment. Our results suggest that anti-HCV core ELISA is more accurate for detecting HCV infection than anti-c100/3. Although the risk associated with the duration of HD treatment and blood transfusion was high, additional factors such as a significant non-transfusional spread of HCV seems to play a role as well. The identification of infective patients by more sensitive methods for HCV genome detection should help to control the transmission of HCV in the unit under study.

Caracterización de tipos antigenícos de rotavirus circulantes en Mendoza, Argentina, en base a tipificación de la proteína de la capside externa VP7 / Characterization of antigenic types of circulating rotavirus in Mendoza, Argentina with base to typing of external VP7 capsid protein

El rotavirus es uno de los agentes etiológicos más comunes de la diarrea aguda de la infancia. La compresión de los mecanismos inmunológicos involucrados en las enfermedades por rotavirus incluso el conocimiento de las variaciones antigénicas, estacionales y geográficas pueden ser cruciales para el desarrollo de la vacuna. Un anticuerpo monoclonal, basado en ELISA, específico para el dominio antigénico sobre la cápside exterior proteica VP7, ha sido desarrollado y usado ampliamente durante los últimos años. Estudiamos la epidemiología del rotavirus VP7, causante de diarrea en niños que consultaron en los dos hospitales principales de Mendoza, Argentina, durante un período de 20 meses. Fueron identificados 227 casos de diarrea, 45 de los cuales (20 por ciento) fueron rotavirus positivas. Pudimos determinar el serotipo de 43 virus (96 por ciento), 42 tipo VP7 y 1 tipo VP7-3. Este último fue detectado hacia el final del segundo año representando posiblemente un tipo VP7 nuevo, que llegaba. Se identificaron 3 patrones electroforéticos, dos correspondientes a la epidemia de tipo VP7 en Mendoza, parecían caracterizados por un patrón relativamente homogéneo de circulación con fuerte predominancia del virus VP7-tipo 1,por lo menos durante el período estudiado de 20 meses, en contraste con lo que se ha informado en ciudades más grandes y cosmopolitas, tales como Buenos Aires