Detection and genotyping of equid herpesvirus 1 in Uruguay.

Infection with equid alphaherpesvirus 1 (EHV-1) causes respiratory disease, abortion and neurological disorders in horses. Molecular epidemiology studies have demonstrated that a single nucleotide polymorphism (A2254/G2254) in the genome region of open reading frame 30 which results in an amino acid variation (N752/D752) of the EHV-1 DNA polymerase, is significantly associated with the neuropathogenic potential of naturally occurring strains. In recent years, an increase in the number of cases of equine neurological disease caused by neuropathogenic variants of EHV-1 has been observed in numerous countries. The purpose of this study was to detect the presence of the viral genome of EHV-1 and equid herpesvirus 4 (EHV-4) in the bronchopulmonary lymph nodes of 47 horses from various locations in Uruguay, obtained from a slaughterhouse, and to determine whether the EHV-1 genomes possessed the mutation associated with neuropathogenesis (G2254/D752). The genes encoding glycoprotein H (gH) of EHV-1 and glycoprotein B (gB) of EHV-4 were amplified by a semi-nested polymerase chain reaction. Of the samples analysed, 28% and 6% of lymph nodes contained the genes for gH and gB, respectively. The viral DNA polymerase gene was amplified and sequenced. Twelve of the 13 genomes sequenced presented the nucleotide G2254, while the remaining 1 showed both nucleotides, A2254 and G2254. The results confirm the presence of EHV-1 in Uruguay. Furthermore, there is evidence for the first time of the detection of EHV-4, and high-frequency detection of the neuropathogenic variant (G2254/D752) of EHV-1 in Uruguay. These findings provide new insights into the epidemiological situation of EHV-1 and EHV-4 in that country.

L'infection par l'herpèsvirus équin de type 1 (EHV-1, sous-famille des alpha- Herpesvirinae) provoque chez les chevaux des maladies respiratoires, des avortements et des troubles neurologiques. Des études d'épidémiologie moléculaire ont montré une corrélation significative entre la présence d'un polymorphisme nucléotidique simple (A2254 / G2254) dans la région génomique du cadre de lecture ouvert 30 (ORF30), se traduisant par une variation des acides aminés (N752 / D752) de l'ADN polymérase du virus EHV-1, et la neuropathogénicité potentielle des souches présentes sur le terrain. On constate depuis quelques années dans de nombreux pays une augmentation du nombre de chevaux atteints de troubles neurologiques dus aux variants neuropathogènes de l'EHV-1. Les auteurs présentent les résultats d'une étude visant à détecter la présence du génome viral de l'EHV-1 et de l'herpèsvirus équin de type 4 (EHV-4) dans des échantillons de ganglions lymphatiques broncho-pulmonaires de 47 chevaux provenant de diverses régions d'Uruguay, collectés à l'abattoir, et à déterminer si les génomes de l'EHV-1 présentaient la mutation associée avec cette neuropathogénicité (G2254 / D752). Dans un premier temps, une amplification en chaîne par polymérase semi-nichée a permis d'amplifier les gènes codant pour la glycoprotéine H (gH) de l'EHV-1 et la glycoprotéine B (gB) de l'EHV-4. Les gènes gH et gB étaient présents respectivement dans 28 % et 6 % des échantillons de ganglions lymphatiques analysés. Le gène de l'ADN polymérase virale a été amplifié puis séquencé. Au total, 12 des 13 génomes séquencés contenaient le nucléotide G2254 tandis que le treizième génome présentait à la fois les nucléotides A2254 et G2254. Ces résultats confirment la présence de l'EHV-1 en Uruguay. En outre, il s'agit du premier rapport faisant état de la présence de l'EHV-4 et de la fréquence de détection du variant neuropathogénique (G2254 / D752) de l'EHV-1 en Uruguay. Ces résultats apportent un nouvel éclairage sur la situation épidémiologique de l'EHV-1 et l'EHV-4 dans ce pays.

La infección por alfa-herpesvirus equino 1 (HVE1) causa en el caballo enfermedades respiratorias, abortos y trastornos neurológicos. Los estudios de epidemiología molecular han demostrado la existencia de una correlación significativa entre el potencial neuropatogénico de cepas presentes en la naturaleza y la presencia de un polimorfismo de nucleótido único (A2254/G2254) en la región genómica del marco abierto de lectura 30 (ORF30). Este polimorfismo se traduce en la variación de un aminoácido (N752/D752) en la ADN-polimerasa del HVE1. En los últimos años se ha observado en muchos países un aumento del número de casos de enfermedad neurológica equina causados por variantes neuropatógenas del HVE1. Los autores describen un estudio encaminado a detectar la presencia de genoma vírico del HVE1 y del herpesvirus equino 4 (HVE4) en ganglios linfáticos broncopulmonares de 47 caballos de varias localidades del Uruguay a partir de muestras obtenidas en mataderos, y a dilucidar después si el genoma de esos HVE1 poseía la mutación ligada a la neuropatogénesis (G2254/D752). En primer lugar se empleó una técnica de reacción en cadena de la polimerasa (PCR) semianidada para amplificar los genes que codifican la glucoproteína H (gH) del HVE1 y la glucoproteína B (gB) del HVE4. De las muestras de ganglios linfáticos analizadas, los genes de la gH y de la gB estaban presentes, respectivamente, en un 28% y un 6%. Se amplificó y secuenció el gen de la ADN-polimerasa vírica. Doce de los trece genomas secuenciados presentaban el nucleótido G2254, mientras que el restante contenía ambos nucleótidos, A2254 y G2254. Los resultados confirman la presencia del HVE1 en el Uruguay. Además, por primera vez, quedó demostrada la presencia del HVE4, así como la elevada frecuencia de la variante neuropatógena (G2254/D752) del HVE1, en el Uruguay. Estos resultados arrojan nueva luz sobre la epidemiología de los virus HVE1 y HVE4 en el país.

Genetic characterization of a pigeon paramyxovirus type 1 isolated from Columba livia in Uruguay.

SUMMARY. The isolation and molecular characterization of pigeon paramyxovirus type 1 (PPMV-1) from a sick racing pigeon in Uruguay is reported for the first time. Hemagglutination inhibition (HI) tests were performed to detect antibodies against avian paramyxovirus serotype 1 (APMV-1), and a HI titer of 1/32 was obtained. Tracheal and cloacal swabs were processed by real-time reverse transcription-polymerase chain reaction (rRT-PCR) with the use of the National Veterinary Services Laboratory-U.S. Department of Agriculture validated matrix (M) gene assay and were positive for APMV-1. Viral isolation in embryonated chicken eggs confirmed the molecular detection of the isolate. A fragment corresponding to the 3' region of the fusion (F) protein gene was amplified by RT-PCR, and subsequently sequenced. The deduced amino acid sequence at the F protein cleavage site displayed the motif 112RRQKR/F117. Phylogenetic analysis of this part of the genome allowed the isolated virus to be grouped in the lineage VIb/ 4b, which suggests that it shares the same ecologic niche with other PPMV-1 that were found in the region, and it is not imported as other European or North American viruses.

Distribution of human papillomavirus genotypes in Paraguayan women according to the severity of the cervical lesion.

The incidence of cervical cancer in Paraguay is among the highest in the world. This study aimed to determine the distribution of human papillomavirus (HPV) genotypes in Paraguayan women, according to the severity of the cervical lesion. This cross-sectional study included 207 women without a squamous intraepithelial lesion, 164 with low-grade squamous intraepithelial lesions, 74 with high-grade squamous intraepithelial lesions, and 41 with cervical cancer. Type-specific HPV was determined by the polymerase chain reaction with MY9/11 L1 and GP5+/GP6+ L1 primers, followed by restriction fragment length polymorphism and reverse line blotting hybridization, respectively. In total, 12 high-risk and 24 low-risk HPVs types were detected. HPV 16 was the most prevalent, followed by HPV 18 in cervical cancer (14.6%), HPV 31 in high-grade squamous intraepithelial lesions (14.9%), HPVs 58/42 in low-grade squamous intraepithelial lesions (9.1% each), and HPVs 31/58 (2.4% each) in women without squamous intraepithelial lesions. Among 285 positive samples, 24.2% harbored multiple HPV types, being this more prevalent in women with squamous intraepithelial lesions (30.8% in low-grade squamous intraepithelial lesions, 22.5% in high-grade squamous intraepithelial lesions, and 22.0% in cervical cancer) than in women without lesions (9.3%). The higher prevalence of HPV 16 and other high-risk HPVs in women both with and without cervical lesions may explain the high incidence of cervical cancer in Paraguay. This information may be of importance for local decision makers to improve prevention strategies. In addition, these results may be useful as baseline pre-vaccination data for a future virological surveillance in Paraguay.

Molecular detection and genetic variability of human metapneumovirus in Uruguay.

Human metapneumovirus (hMPV) has been described as circulating among the Uruguayan population at least since 1998 based on serologic evidence. However, no isolation attempts, molecular detection, or genetic studies have been carried out so far in the country. In the present study, molecular detection of circulating hMPV in children hospitalized with acute respiratory tract infection in Montevideo-Uruguay was carried out by reverse transcription-polymerase chain reaction (RT-PCR) amplification of the hMPV nucleoprotein (N) gene from 217 nasopharyngeal aspirates. Genetic variability analysis of the positive samples was performed by amplification and sequencing of both N and attachment glycoprotein (G) genes. Eighteen of the 217 samples tested positive for hMPV, with tachypnea, chest indrawing, and wheezing being the main clinical symptoms recorded. Phylogenetic analysis of N and G genes showed that Uruguayan samples clustered in genotypes described previously as A2, B1, and B2, with bootstrap values >or=98%. Sublineages A2a and A2b could also be distinguished within the samples that belong to A2. This is the first molecular report on the circulation of hMPV in Uruguay. The pattern of circulation of this virus, analyzed for both N and G genes independently, resembles the complex evolutionary pattern of respiratory syncytial virus (RSV).

First-time detection of porcine reproductive and respiratory syndrome virus (PRRSV) infection in Uruguay.

Within the last two decades, several high-impact viruses have emerged in the global swine population, including porcine reproductive and respiratory syndrome virus (PRRSV). In Uruguay, the more recent serological survey for PRRSV and other notifiable diseases such as Aujeszky's disease virus (ADV) and classical swine fever virus (CSFV) dated from year 2000. The main purpose of this study was to update our information on the infection status of PRRSV, ADV and CSFV in Uruguayan pig herds, in order to keep informed about the epidemiological situation of these notifiable infections in the country. For serological testing, a total of 524 swine serum samples collected during the period 2014-2016 were assayed by commercial ELISAs. Our results revealed the (unexpected) presence of PRRSV antibodies in Uruguayan domestic swine herds and confirmed the absence of ADV and CSFV antibodies in all of the assessed samples. Following such initial finding, PRRSV antibodies were further investigated in 23 retrospective samples collected during 2010-2014. Thirteen of these 23 samples resulted seropositive. Subsequently, a molecular detection approach in frozen serum samples was implemented to confirm PRRSV infection, and viral RNA was identified by reverse transcription-nested polymerase chain reaction (RT-nPCR). Fourteen of 86 evaluated 2014-2016 samples resulted positive for viral RNA, while molecular analysis of four retrospective samples also revealed the presence of PRRSV type 2. Viral isolation of selected samples was carried out in porcine alveolar macrophages (PAM) and MARC 145 simian kidney cells, and the virus identity was confirmed by cytopathic effect (CPE) and immunofluorescence assay (IFA) using specific monoclonal antibodies for PRRSV nucleocapsid. Data reported here evidence for the first time the circulation of PRRSV type 2 in Uruguay, and retrospective serology results suggest that the virus has been infecting pigs in this country at least since 2011.

Genotyping of Uruguayan Human adenovirus isolates collected between 1994 and 1998.

Adenoviruses are one of the most frequent causative agents of acute lower respiratory infections in infants and young children. Twenty-three adenovirus isolates from nasopharyngeal aspirates of children hospitalized for acute lower respiratory infections in Uruguay between 1994 and 1998 were studied by restriction enzyme analysis. The genomic analysis showed that 60.9% (n = 14) of isolates belonged to the species Human adenovirus C (HAdV-C) and 31.9% (n = 9) to the species Human adenovirus B (HAdV-B). Whereas some isolates could be classified according to the published profiles into genotype or genomic variant, others displayed migration patterns not allowing classification. Eight isolates (89%) of HAdV-B corresponded to the Ad7h genotype that has been associated with severe and fatal pneumonia and necrotizing bronchiolitis in children in South America. The isolates of HAdV-C showed a great variability in accordance with the data published earlier.

Genetic stability of the attachment glycoprotein of human respiratory syncytial viruses during serial passages in cell cultures.

Thirteen isolates of human respiratory syncytial viruses (HRSV) of groups A and B were isolated in HEp-2 cells from nasopharyngeal aspirates (NPA) from the children with acute respiratory infections. Three isolates of HRSV of group A were propagated in HEp-2 cells in 20 serial passages. Nucleotide sequences of the products obtained by RT-PCR from the glycoprotein (G) hypervariable region of the original virus isolates in NPA and those after one or several passages were compared. All the isolates analyzed showed no changes during passaging in HEp-2 cells.

Acute diarrhea in Paraguayan children population: detection of rotavirus electropherotypes.

Group A rotavirus infections were detected in 93 of 410 fecal samples from children with acute diarrhea, admitted in three main hospitals of Asunción, Paraguay, from August 1998 to August 2000. Most of the rotavirus-infected patients were admitted during the winter season in the three epidemic years. The rotavirus infection rate was highest in infants from 6 to 23 months of age. In the 93 samples examined, 10 different rotavirus electropherotypes were recognized, but two of them largely predominated. Only one sample showed a short electropherotype pattern, thus indicating a minor involvement of the rotavirus subgroup I in rotaviral acute diarrhea in the area and the time during which the survey was carried out.

Electropherotypes of rotaviral RNA from cases of infantile diarrhea in Uruguay.

Electropherotypes of human rotavirus isolates from infants with acute diarrhea belonging to two populations with different clinical features were determined. Thirteen electropherotypes were identified in total 69 isolates; 46 (66.6%) isolates had long RNA migration patterns and 23 (33.3%) isolates had short migration pattern. One of the long-pattern electropherotypes (47.82% of the total electropherotypes) was predominant. It was detected in both populations almost throughout the whole period of the study, while other electropherotypes were found only occasionally. The co-circulation of long and short electropherotypes was not frequent.

[Comparison between immunofluorescence and immunoenzymatic assay for the rapid diagnosis of the respiratory syncytial virus in nasopharyngeal secretions]. / Comparación entre la inmunofluorescencia y el ensayo inmunoenzimático para el diagnóstico rápido del virus respiratorio sincicial en secreciones nasofaríngeas.

An enzyme immunoassay, RSV-EIA Abbot, was evaluated by comparison with indirect immunofluorescence. Nasopharyngeal secretions obtained from 95 infants and young children with acute respiratory infections were examined for the presence of respiratory syncytial virus antigens with both methods. Specimens were stored at -70 degrees C before being tested by EIA. Out of 60 samples positive by indirect immunofluorescence, 46 were also positive by RSV-EIA (sensitivity 78.7%) and 34 out of 35 immunofluorescence negative specimens were negative by RSV-EIA (specificity 97.1%). Therefore, the EIA appears to be an acceptable test for the rapid detection of RSV as an alternative for indirect immunofluorescence.

Una propuesta rápida y económica para detectar el virus de papiloma humano por PCR a partir de muestras cervicales con reactivo desnaturalizante / A rapid and economic option for human papillomavirus detection by PCR in cervical samples with denaturing reagent

Trabajos han demostrado la utilidad de la captura híbrida II (CH II®) en la detección del virus de papiloma humano de alto riesgo oncogénico (HR-HPV) como método de tamizaje primario para detección de cáncer de cuello uterino, así como las bondades de la PCR que permite acceder a métodos de tipificación viral. Por ello el objetivo fue detectar el genoma del HPV por PCR a partir de muestras de CH II® cien veces diluidas. Estudio transversal en 141 muestras cervicales de mujeres con citología normal y anormal que concurrieron al IICS, UNA. Las muestras fueron procesadas por CH II® y almacenadas con reactivo desnaturalizante a -80ºC. Luego, las muestras fueron diluidas 100 veces con agua destilada y posteriormente procesadas por PCR. Se detectó HPV en 51% y 43% de las muestras analizadas por CH II® y PCR, respectivamente. Diecisiete de 23 muestras positivas por CH II® con carga viral relativa baja fueron negativas por PCR. Esto podría deberse a la degradación del material. Además, 6 muestras negativas por CH II® fueron positivas por PCR sugiriendo presencia de infección con tipos virales no incluidos en CH II® . Estos resultados sugieren que es posible realizar la detección de HPV por PCR en muestras procesadas por CH II® previa dilución. Esta propuesta rápida, sencilla y económica, minimiza el riesgo de perder el material genético en la extracción y permite acceder a métodos de tipificación viral que podrían contribuir con datos sobre tipos de HPV circulantes para realizar una vigilancia en la era post-vacunal.

Studies havedemonstrated the usefulness of the hybrid capture II (CHII) in thedetection of oncogenic high risk human papillomavirus (HR-HPV) asaprimaryscreeningmethod for detection of cervical cancer, as well as the benefits of PCR that allows accessto viral typing methods. The objective was todetect HPV by PCR from cervical samplesprocessed by CH II.It was a cross-sectional study including141cervicalsamples ofwomenattendingtheIICS,UNA. Thesampleswereprocessed by CH IIand storedwithdenaturing reagent at-80ºC.Then,theywere diluted 100 times with distilled water andsubsequently processed by PCR. HPV was detected in 51% and 43% of the samples analyzed by CH IIand PCR respectively. Seventeen of 23 positive samples by CH IIwith relatively low viral load were negative by PCR. This could be due to degradation ofthe material. In addition,sixnegative samples by CH IIwere positive by PCR suggestingthe presence of infection with HPV types not included in CH II. These results suggestthat it is possible to detect HPV by PCRfrom samples processed by CH IIprior dilution.This is a quick, easy and economic alternative which minimizes the risk of losing thegenetic material in the extraction process,and allows access to viral typing methods thatcouldprovide data aboutcirculating HPVtypesto carry out surveillance in thepost-vaccine era.

Sequence and phylogenetic analysis of the VP4 gene of human rotaviruses isolated in Paraguay.

Nucleotide and amino acid analyzes of the VP4 gene of human rotaviruses isolated both in Paraguay and worldwide were carried out in order to increase our knowledge about the complex pattern of evolution of this virus in nature. Paraguayan strains bearing the P[8] genotype were grouped in the lineages P[8]-1, P[8]-2, and P[8]-3. Regardless of the year of detection, all of the G4 and G9 strains were related to lineage P[8]-3, whereas the G1 strains were related to the three lineages detected in Paraguay; this fact reinforces the notion of the existence of constraints within specific populations of rotavirus strains except for the G1 strains. In addition, we propose a phylogenetic classification for the P[4] strains in five different lineages (i.e. P[4]-1 to P[4]-5). The findings presented in this paper reinforce the importance of a continuous surveillance of rotavirus strains in order to predict the possible variants that will circulate in a country, and ultimately improve current vaccination programs.

Características clínico-demográficas y tipificación del virus de papiloma humano en mujeres paraguayas con citologías negativas para lesión escamosa intraepitelial / Clinical-demographic characteristics and typification of the human papilloma virus in Paraguayan women with negative citology for squamous intraepithelial lesion

Paraguay posee una alta tasa de incidencia de cáncer de cuello uterino de 35/100.0000 mujeres en el año 2008 y el virus de papiloma humano (HPV) es su agente causal. La planificación de medidas de prevención puede ser beneficiada con conocimientos sobre los tipos virales, por ello, el objetivo de este estudio fue determinar características clínico-demográficas y los tipos de HPV presentes en mujeres con citología negativa para lesión escamosa intraepitelial. Estudio de corte transverso con componente analítico en 207 mujeres con citología negativa para lesión escamosa intraepitelial provenientes de centros de salud de Asunción. La tipificación fue realizada por reacción en cadena de la polimerasa utilizando cebadores MY09/11 y GP5/GP6, seguida de polimorfismo de longitud de fragmentos de restricción e hibridación lineal reversa, respectivamente. La asociación entre HPV y las características clínico-demográficas fue determinada por análisis de Chi cuadrado (EpiInfo versión 3,2). Se detectó alta frecuencia de HPV (21%), siendo el tipo predominante HPV 16 (4,3%) seguido de HPV 58/31 (2,4% cada uno). Se observó asociación entre la presencia de HPV y la edad (p=0,0002), detectándose mayor frecuencia de HPV en mujeres menores a 30 años, la cual, disminuyó al aumentar la edad, presentando un ligero aumento en mujeres de 60 años o más. En conclusión, los datos muestran una alta frecuencia de HPV y HPV 16 en mujeres menores a 30 años con citología negativa y sugieren la necesidad de realizar control posteriormente, a fin de identificar las infecciones persistentes que podrían causar lesión de cuello uterino

Genotypes of respiratory syncytial virus group B identified in Uruguay.

Genotypes of Human respiratory syncytial virus (HRSV) of group B from Uruguay were assigned to strains isolated during 1999 and 2001 outbreaks and others formerly reported isolated in the period 1989-1996. The nucleotide sequences of the C-terminal portion of the G protein were compared to sequences representative of previously defined HRSV genotypes. Most Uruguayan strains clustered into five of the previously identified genotypes. Nine isolates clustered in two genotypes named URU1 and URU2 which were not described up to present. Two of the analyzed sequences isolated in 2001 have a six nucleotide duplication that is discussed in terms of HRSV variability.

Respiratory syncytial virus: changes in prevalence of subgroups A and B among Argentinian children, 1990-1996.

The frequency of respiratory syncytial virus (RSV) and the distribution of subgroups A and B strains during 7 consecutive years (1990-1996) were examined in two cities of Argentina. Nasopharyngeal aspirates from 1,304 children less than 2 years of age hospitalized with acute lower respiratory infection were studied by indirect immunofluorescence. RSV was detected in 352 cases (26.9%), and the peak activity was observed in midwinter. Subgroup characterization was performed with two monoclonal antibodies against the F protein on nasopharyngeal aspirate smears. Of 195 samples, 174 (89.2%) were identified as subgroup A strains and 21 (10.8%) as subgroup B. Both strains cocirculated during 5 of 7 years studied with subgroup A predominating. Subgroup A occurred at least 8 times as often in all years except for 1994-1995. Children infected by subgroup A were younger than those infected by subgroup B (P < 0.05). The association of subgroup A infection with bronchiolitis and subgroup B with pneumonia was statistically significant (P < 0.03).

Identification of viruses in a study of acute respiratory tract infection in children from Uruguay.

For the purpose of identifying viral agents associated with acute respiratory tract infections (ARI) in children less than 5 years old, a longitudinal community study was undertaken in Montevideo, Uruguay, from May 1985 to December 1987. This report includes results obtained by cell culture and immunofluorescence techniques for detection of respiratory syncytial virus (RSV), influenza A and B viruses, parainfluenza 1 and 3 viruses, and adenovirus. Two populations were studied: children visited at home by pediatricians (group 1) and children with an ARI episode who attended an outpatient clinic (group 2). Nasopharyngeal aspirates were obtained at the time of an ARI episode: 858 from group 1 and 488 from group 2. Viruses were identified in 15.3% of group 1 specimens and in 17.6% of group 2 specimens. RSV was the most frequently recovered agent, accounting for 67.9% and 58.1%, respectively, of all viruses detected. The sensitivity and specificity of RSV isolation by cell culture are compared with detection by indirect immunofluorescence.

Evolutionary pattern of the G glycoprotein of human respiratory syncytial viruses from antigenic group B: the use of alternative termination codons and lineage diversification.

Partial sequences of the G protein gene of 33 isolates from antigenic group B of human respiratory syncytial virus were determined. Phylogenetic analysis indicated that the evolutionary pattern of group B viruses is similar to that previously described for isolates of antigenic group A, including worldwide distribution of related viruses and co-circulation of viruses from different lineages during the same epidemic. Dominance of AG+GA over UC+CU transitions was observed when G sequences of group B viruses were compared, as previously found in viruses from antigenic group A. Interestingly, differences in protein length, determined by the usage of alternative termination codons, were more pronounced in group B than in group A viruses. Changes in protein length correlated with the classification of viruses in different lineages. Thus, mutations that determined termination codon usage seem to have played an important role in the diversification of group B viruses.

Antigenic structure of human respiratory syncytial virus fusion glycoprotein.

New series of escape mutants of human respiratory syncytial virus were prepared with monoclonal antibodies specific for the fusion (F) protein. Sequence changes selected in the escape mutants identified two new antigenic sites (V and VI) recognized by neutralizing antibodies and a group-specific site (I) in the F1 chain of the F molecule. The new epitopes, and previously identified antigenic sites, were incorporated into a refined prediction of secondary-structure motifs to generate a detailed antigenic map of the F glycoprotein.

Antigenic characterization of respiratory syncytial virus associated with acute respiratory infections in Uruguayan children from 1985 to 1987.

The occurrence of subgroup A and B strains of respiratory syncytial virus (RSV) was studied during three epidemic years, 1985 to 1987, in Uruguay. A set of monoclonal antibodies was selected according to their reactivity with local RSV isolates and used for the typing of RSV directly in nasopharyngeal cells by indirect immunofluorescence. Of 77 specimens, 69 could be typed as belonging to subgroup A or B, 5 could not be typed with the restricted set of monoclonal antibodies employed, and 3 reacted with both subgroup-specific antibodies. In 1985 and 1986 subgroup A predominated, accounting for 65.7% of all typed specimens, but in 1987 subgroup B surpassed subgroup A, accounting for 82.4% of the samples.

Evolution of the G and P genes of human respiratory syncytial virus (subgroup A) studied by the RNase A mismatch cleavage method.

The G and P genes of human respiratory syncytial viruses (subgroup A), isolated between 1961 and 1989, were analyzed by RNase A one-dimensional fingerprinting, using the Long strain as the reference. Total RNA extracted from cells infected with the different isolates was hybridized to radiolabeled antisense G or P RNA probes of the Long virus. The RNA:RNA heteroduplexes were digested with RNase A and the resistant products analyzed by gel electrophoresis. Comparative analysis of the cleavage patterns revealed extensive genetic heterogeneity in both genes among viruses isolated in different epidemics. In contrast, 13 viruses isolated in Montevideo during a 3-month period showed much more restricted heterogeneity; thus, 11 viruses represented the predominant type of this outbreak and only 2 other viruses generated different RNA cleavage patterns distantly related to the major type. Statistical analysis of the results obtained indicated progressive accumulation of genetic changes with time along cocirculating evolutionary lineages within the same antigenic subgroup of RS virus. The results are discussed in terms of a model for RS virus evolution.