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The coxsackievirus-adenovirus receptor protein can function as a cellular attachment protein for adenovirus serotypes from subgroups A, C, D, E, and F.

Attachment of an adenovirus (Ad) to a cell is mediated by the capsid fiber protein. To date, only the cellular fiber receptor for subgroup C serotypes 2 and 5, the so-called coxsackievirus-adenovirus receptor (CAR) protein, has been identified and cloned. Previous data suggested that the fiber of the subgroup D serotype Ad9 also recognizes CAR, since Ad9 and Ad2 fiber knobs cross-blocked each other's cellular binding. Recombinant fiber knobs and 3H-labeled Ad virions from serotypes representing all six subgroups (A to F) were used to determine whether the knobs cross-blocked the binding of virions from different subgroups. With the exception of subgroup B, all subgroup representatives cross-competed, suggesting that they use CAR as a cellular fiber receptor as well. This result was confirmed by showing that CAR, produced in a soluble recombinant form (sCAR), bound to nitrocellulose-immobilized virions from the different subgroups except subgroup B. Similar results were found for blotted fiber knob proteins. The subgroup F virus Ad41 has both short and long fibers, but only the long fiber bound sCAR. The sCAR protein blocked the attachment of all virus serotypes that bound CAR. Moreover, CHO cells expressing human CAR, in contrast to untransformed CHO cells, all specifically bound the sCAR-binding serotypes. We conclude therefore that Ad serotypes from subgroups A, C, D, E, and F all use CAR as a cellular fiber receptor.

Adenoviridae↗

Circulation of group A rotavirus subgroups and serotypes in Pune, India, 1990-1997.

Group A rotavirus-positive stool specimens, collected from 432 hospitalized patients of all age groups with diarrhoea during 1990-1997 from Pune, India, were characterized for subgroups (SGs) and G serotypes (1, 2, 3, 4, 6, 8, and 10). ELISA for subgrouping was carried out by employing subgroup I and II-specific monoclonal antibodies (MAbs). For serotyping, MAbs against G1 (Ku), G2 (S2), G3 (Yo), and G4 (ST-3) were used. In addition, MAbs against G3 (RV-3), G8 (B37), G6 (bovine U.K.), and G10 (B223) were also employed. Of the 432 specimens, 174 (40.27%) belonged to subgroup I, 187 (43.29%) to subgroup II, 15 (3.47%) to subgroup I and II, and 56 (12.96%) did not react to MAbs specific to subgroup I and subgroup II MAbs. Of the 432 specimens, 111 (25.69%) reacted to one of the MAbs used. Thirty-five of the 111 specimens were serotyped as G1, 34 as G2, and 42 as G3, G4, G6, G8, and G10. Sixty-seven (21%) specimens gave dual reaction mainly to MAbs against G6, G10; G2, and G4, and in several other combinations. Forty-seven specimens (10.88%) showed multireactivities. A large number of specimens (47.92%) did not show any reactivity with MAbs employed in this study, and remained non-serotypeable. Subgroup I was found to be more common in Pune, and most specimens negative for subgroup I and II were non-serotypeable. The results implicate the need for characterization of unusual and non-typeable strains before undertaking any rotaviral vaccine studies in India.

Adolescent↗

Medial rectus subgroups of the oculomotor nucleus ant their abducens internuclear input in the monkey.

Physiological experiments show that the abducens internuclear pathway is involved in the activation of only the medial rectus (MR) eye muscle. Previous anatomical experiments have shown that this pathway terminates in multiple foci within the oculomotor nucleus (OMN) of the monkey, and not only over the classical motoneuron subgroup. In this study the location of MR motoneurons in the monkey OMN is reinvestigated, and compared with the detailed pattern of terminations of the abducens internuclear pathway. The motoneurons were labelled by injections of retrograde tracer substances, HRP and [125I] wheat germ agglutinin (WGA), into extraocular muscles. Labelled MR motoneurons were found in three main divisions, called subgroup A, B, and C. Subgroup A corresponds mainly to the classical ventral MR subgroup. Subgroup B lies dorsal and caudal in OMN, occupying an area classically reserved for inferior rectus (IR). However, the representation of IR is shown to be further rostral in the dorsal OMN. Subgroup C is on the dorsomedial border of OMN. Its cells are significantly smaller than those of Group A and B. In addition C could be labelled independently of the other subgroups by small injections into the outer (orbital) layer of MR muscle. This indicates a functional difference between the subgroups. It is suggested that subgroup C may be important for the tonic component of MR activity, possibly convergence. The location of abducens internuclear terminals, labelled by the injection of tritiated amino acids into the abducens nucleus, corresponds exactly to the position of MR motoneurons. These experiments provide a new picture of the internal OMN organization, and support the physiological findings that the abducens internuclear pathway activates only MR motoneurons.

Abducens Nerve↗

Clinical trials of behavioural interventions with heterogeneous teaching subgroup effects.

Behaviour modification is often delivered to teaching subgroups. For example, experimental and control smoking cessation programmes may be given to 15 classes (subgroups) with 10 (otherwise independent) individuals. We present general statistical tests and power estimates to compare continuous outcomes from two interventions in settings where the magnitude of teaching subgroup heterogeneity, number of subgroups and subgroup size can differ between intervention arms. An application is made to data from a trial to reduce disease-transmitting sexual behaviour. The statistical impact of teaching subgroup heterogeneity effect increases as the (a) number of participants in a subgroup increases, and (b) ratio of 'averaged experimental and control subgroup effect variance' to study subject variance increases. If plausible levels of subgroup teaching effect heterogeneity are ignored, the true sizes of tests with nominal 0.05 two-sided type I errors range from 0.055 to 0.47, while when planning studies, estimated sample sizes are only 11.1-95.2 per cent of the true requirements.

Behavior Therapy↗

High proportion of subgroup A' (genotype A) among Brazilian isolates of Hepatitis B virus.

Hepatitis B virus (HBV) genotype A has been divided recently into two subgroups, designated A-A' (genotype A excluding A') and A'. Isolates belonging to subgroup A' have been identified in Africa. A new genotyping method, based on PCR amplification of the pre-S/S genome region and subsequent restriction fragment length polymorphism (RFLP) analysis, was developed, that established a correlation between RFLP subtypes and subgroups within genotype A. To investigate the occurrence of subgroup A' in South America, 119 Brazilian HBV isolates were analyzed. Ninety-three (78%) of them belonged to genotype A, with three predominating RFLP subtypes: 44 (37%) isolates were classified as AI, 30 (25%) were AII, and 18 (15%) were AIII. Pre-S/S nucleotide sequences of 15 genotype A isolates were determined. Phylogenetic analysis performed with these 15 and an additional 41 sequences revealed that isolates AI and AII clustered in subgroup A', whereas isolates AIII were classified into subgroup A-A'. The correlation RFLP subtypes-subgroups was confirmed by the presence of amino acid residues specific for subgroup A' in the surface antigens and polymerase of isolates AI and AII. The high proportion (63%) of isolates from subgroup A' suggested an African origin for a large number of Brazilian HBVs.

Amino Acids↗

Evoked potential variation in schizophrenic subgroups.

Unmedicated chronic schizophrenic inpatients and nonpsychotic controls were tested in a paradigm designed to elicit habituated event-related potentials (ERPs) to auditory stimuli. Analysis of Variance of the ERP components recorded at bilateral frontal (F1 and F2) and temporal (T3 and T4) scalp leads revealed significant decreases in N1 component amplitudes in both frontal leads in the schizophrenic subjects. P2 and N2 amplitudes also tended to be smaller at frontal leads in the schizophrenic subjects, but these differences were not found to be statistically significant overall. The schizophrenic subjects were assigned to diagnostic subgroups following administration of the Diagnostic Interview Schedule, the Maine Paranoid Scale, and the Scale for the Assessment of Negative Symptoms. Subjects meeting DSM-III criteria for paranoid schizophrenia were assigned to one subgroup (PS subgroup), and those meeting DSM-III criteria for residual or undifferentiated schizophrenia were assigned to another subgroup (RS subgroup). The Analysis of Variance of the N1 amplitude measures was repeated with subgroup diagnosis as a factor, revealing significant decreases in N1 amplitude in the PS, but not the RS, patients. Patients in the PS subgroup were found to differ significantly from those in the RS subgroup on this ERP measure, as well as from controls. These results suggest that subgroup differences exist within the schizophrenic population that are reflected in differential changes in ERP morphology.

Adult↗

Dysfunctional belief-based obsessive-compulsive disorder subgroups.

An attempt was made to identify obsessive-compulsive disorder (OCD) subgroups based on differences in OCD related beliefs. OCD patients (N=367) were assessed with the Obsessional-Beliefs Questionnaire prior to treatment. Individuals' scores on measures of inflated personal responsibility and the tendency to overestimate threat, perfectionism and intolerance of uncertainty, and over-importance and over-control of thoughts were subjected to cluster analysis. Support for both a simple and complex subgroup model was found (2-subgroup and 5-subgroup taxonomies). A low-beliefs subgroup was identified in both taxonomies. The low-beliefs subgroups reported scores on belief measures equivalent to scores reported for non-OCD comparison groups in earlier studies. Additional analyses were conducted to determine relations between belief-based and symptom subgroups. Significant relationships were found (e.g., Symmetry symptom subgroup membership was associated with membership in the Perfectionism/Certainty beliefs subgroup), although the shared variance was modest. Implications for understanding OCD heterogeneity and for cognitive theory are discussed.

Adult↗

The phylogeny of the subgroups within the melanogaster species group: likelihood tests on COI and COII sequences and a Bayesian estimate of phylogeny.

The relationships among the majority of the subgroups in the Drosophila melanogaster species group remain unresolved. We present a 2223basepair dataset for mitochondrial cytochrome oxidase I and cytochrome oxidase II for 43 species (including new data from 11 species), sampled to include the major subgroups. After a brief review of competing hypotheses for the ananassae, montium, suzukii, and takahashii subgroups, we combine the two genes based on a new use of the SH test and present KH and SH likelihood comparisons (Kishino and Hasegawa, 1989. J. Mol. Evol. 29, 170-179; Shimodaira and Hasegawa, 1999) to test the monophyly and placement of these subgroups within the larger species group. Although we find insignificant differences between the two suggested placements for the ananassae subgroup, the ananassae is sister to the rest of the subgroups in the melanogaster species group in every investigation. For the takahashii subgroup, although we cannot reject monophyly, the species are so closely related to the suzukii subgroup for these data that the two subgroups often form one clade. Finally, we present a Bayesian estimate of the phylogeny for both genes combined, utilizing a recently published method that allows for different models of evolution for different sites.

Animals↗

Perceived spouse responsiveness to chronic pain: three empirical subgroups.

The spouse plays a fundamental role in day-to-day functioning and long-term well-being of the patient with chronic pain. Although spouses may respond differently to pain demonstrations, no study has examined patterns of perceived spouse responsiveness to chronic pain behavior. Yet perceived patterns of response to chronic pain may explain variability in pain behavior in the literature because studied samples may be drawn from any one subgroup. The purposes of this study were to run an exploratory cluster analysis to identify naturally occurring spouse response subgroups by using section 2 of the Multidimensional Pain Inventory and to examine pain-relevant variables between subgroups. It was hypothesized that subgroups would be identified and that they would differ on pain-relevant variables. Participants were 774 married pain patients from 2 University of Florida-affiliated pain clinics, 69% of whom experienced chronic low back pain. A hierarchical cluster analysis identified 3 subgroups that were labeled positively attentive, negatively attentive, and inattentive. A discriminant analysis yielded 2 significant discriminant functions that correctly classified 71.1% of subgroup membership. The support variable best differentiated between the positively and negatively attentive subgroups, whereas interference best distinguished between the negatively attentive and inattentive subgroups. Results suggest the profiles have conceptual and clinical validity, with the negatively and positively attentive subgroups exhibiting the poorest adjustment to pain. A controlled study is needed to determine the direction of causality.

Journal Article↗

Respiratory syncytial virus epidemics: variable dominance of subgroups A and B strains among children, 1981-1986.

We examined the distribution of subgroups A and B strains from respiratory syncytial virus during five epidemic years from 1981 to 1986 in Huntington, West Virginia. Of 235 infants and children with respiratory syncytial virus infection, 211 had virus reisolated from frozen throat swab specimens for subgroup characterization by reactivity with a panel of monoclonal antibodies to the G, F, NP, M, and P proteins by using an enzyme immunoassay. We identified 160 (75.8%) strains as subgroup A and 51 (24.2%) as subgroup B. Strains of both subgroups were isolated in all years. Small, but approximately equal, numbers of subgroup B strains were isolated each epidemic year. By contrast, subgroup A strains occurred at least three times as often in all years except 1984-1985. The very low number of subgroup A strains isolated during the 1984-1985 epidemic gave dominance to subgroup B strains.

Antibodies, Monoclonal↗

Effect of murine thymic epithelial cell line (MTEC1) on the functional expression of CD4(+)CD8(-) thymocyte subgroups.

To determine the effect of thymic stromal cells on the functional maturation of CD4 single-positive (SP) thymocytes, the functional status of isolated CD4 SP thymocyte subgroups was investigated by means of cell proliferation and cytokine production in response to concanavalin A (Con A) prior and after co-culturing with a murine thymic epithelial cell line (MTEC1). Mouse medullary CD4 SP thymocytes were phenotypically divided into seven discrete subgroups predicted to reflect the maturation pathway from newly emerging CD4 SP thymocytes to terminally differentiated cells. For functional analysis, six major subgroups (6C10(+)CD69(+), 6C10(-)CD69(+), 6C10(-)CD69(-)3G11(+)Qa-2(-), 6C10(-)CD69(-)3G11(+)Qa-2(+), 6C10(-)CD69(-)3G11(-)Qa-2(-) and 6C10(-)CD69(-)3G11(-)Qa-2(+)) cells were isolated and their functional status in response to Con A stimulation assessed. A functional hierarchy is revealed among these subgroups, consistent with their phenotypic maturation status, which may imply that these cells undergo a functional maturation process within thymic medulla. The function of cytokine production by CD4 SP thymocytes is acquired in a stepwise manner from a low to high level and characterized by T(h)0-type cytokines in the main stream of differentiation pathway. However, a minor subgroup that appeared at the late stage as 3G11(-)6C10(-) cells was biased to produce T(h)2-type cytokines. Nevertheless, the functional capacity of the final two Qa-2(+) subgroups of CD4 SP thymocytes was still significantly lower than that of spleen CD4(+) T cells. After co-cultivation with MTEC1 cells, four subgroups of TCRalphabeta(+)CD4(+)CD8(-) thymocytes exhibited significantly higher levels of proliferation capability and modulation in cytokine production capability. However, co-culturing with MTEC1 cells did not change the pattern of T(h)0- or T(h)2-like cytokine production by respectively medullary CD4 SP thymocyte subgroups nor could MTEC1 induce CD4 SP thymocytes to secrete T(h)1-type cytokines. The results suggest that MTEC1 can regulate the functional status of these thymocyte subgroups.

Animals↗

The medical genetics workforce: an analysis of clinical geneticist subgroups.

PURPOSE: Clinical geneticists with a Doctor of Medicine degree face challenges to meet the growing population demand for genetic services. This study was designed to assist the profession with workforce planning by identifying clinically relevant subgroups of geneticists and describing their professional characteristics and clinical practices. Geneticists' patient care productivity is compared across subgroups and other medical specialists. METHODS: Part of a comprehensive national study of genetic services and the health workforce, this study uses data from a 2003 survey of geneticists certified by the American Board of Medical Genetics. This study includes 610 clinical geneticists who spend at least 5% of their time in direct patient-care services. An iterative approach was used to identify five subgroups based on the types of new patients seen. We conducted a descriptive analysis of subgroups by demographic, training, professional, and practice characteristics. RESULTS: The subgroups include general (36%), pediatric (28%), reproductive (15%), metabolic (14%), and adult (7%) geneticists. Clinically relevant variations across subgroups were noted in training, professional, and practice parameters. Subgroups vary across patient care hours (median, 15-33 hours/week) and total weekly work hours (52-60 hours). New patient visits (mean, 222-900/year) are higher than follow-up patient visits (mean, 155-405) for all subgroups except metabolic geneticists. CONCLUSION: Although many geneticists practice as generalist geneticists, this study provides an evidence base for distinguishing clinically relevant subgroups of geneticists. Geneticists provide similar numbers of new patient visits and far fewer follow-up visits than other medical specialists. These findings are relevant to geneticist workforce planning.

Data Collection↗

Clinical and epidemiological features of acute infantile gastroenteritis associated with human rotavirus subgroups 1 and 2.

During a prospective 1-year study rotavirus isolates from 169 children with gastroenteritis were investigated by polyacrylamide gel electrophoresis. A total of 118 (70%) of the strains analyzed contained sufficient viral nucleic acid to give visible electrophoretic patterns; 36% were identified as strains belonging to subgroup 1 (short patterns), and 64% were identified as strains belonging to subgroup 2 (long patterns). The two subgroups cocirculated at equal frequencies during the first 7 months of the year, after which subgroup 1 rotavirus completely disappeared. Subgroup 2 rotavirus occurred throughout the year. No significant differences between the subgroups in relation to age or sex distribution were observed. Fever and temperatures exceeding 39 degrees C were significantly more frequent in children who shed rotavirus subgroup 1. Diarrhea and vomiting occurred at similar rates in both groups of patients, but were more pronounced in children who shed rotavirus subgroup 2. One of three dominant electropherotypic variants of subgroup 2 rotavirus was found to be associated with more intense symptoms, higher rates of hospitalization, and a significantly higher frequency of respiratory symptoms; the clinical picture may indicate that this rotavirus electropherotype has higher virulence.

Adolescent↗

Respiratory syncytial virus subgroup B dominance during one winter season between 1987 and 1992 in Vancouver, Canada.

A subgroup analysis of 613 specimens submitted to the British Columbia's Children's Hospital from 1987 to 1992 revealed that subgroups A and B of respiratory syncytial virus (RSV) were both circulating in our community, with some predominance for subgroup A during the period from October 1987 to September 1988 (the 1987-88 season) (64%), 1990-91 (60%), and 1991-92 (62%). During 1989-90 subgroup A represented the majority of isolates (80%). Subgroup B predominated during only one season, 1988-89 (94%). No microheterogeneity within subgroups was apparent as judged by the monoclonal antibody reactivity pattern. More male than female children were affected overall, but no sex-related difference between subgroup infections could be detected (P = 0.28). The majority of patients were less than 1 year of age, and no significant association between age and subgroup was detected after stratifying for year (P = 0.64). This is, to our knowledge, the first comprehensive longitudinal RSV subgroup prevalence study from the Pacific Northwest and from Canada.

Adolescent↗

Genetic analysis of the Rous sarcoma virus subgroup D env gene: mammal tropism correlates with temperature sensitivity of gp85.

Subgroup D avian sarcoma and leukosis viruses can penetrate a variety of mammalian cells in addition to cells from their natural host, chickens. Sequences derived from the gp85-coding domain within the env gene of a mammal-tropic subgroup D virus (Schmidt-Ruppin D strain of Rous sarcoma virus [SR-D RSV]) and a non-mammal-tropic subgroup B virus (Rous-associated virus type 2) were recombined to map genetic determinants that allow penetration of mammalian cells. The following conclusions were based on host range analysis of the recombinant viruses. (i) The determinants of gp85 that result in the mammal tropism phenotype of SR-D RSV are encoded within the 160 codons that lie 3' of codon 121 from the corresponding amino terminus of the gp85 protein. (ii) Small linear domains of the SR-D RSV gp85-coding domain placed in the subgroup B background did not yield viruses with titers equal to that of the subgroup D virus in a human cell line. (iii) Recombinant viruses that contained subgroup D sequences within the hr1 variable domain of gp85 showed modest-to-significant increases in infectivity on human cells relative to chicken cells. A recombinant virus that contained three fortuitous amino acid substitutions in the gp85-coding domain was found to penetrate the human cell line and give a titer similar to that of the subgroup D virus. In addition, we found that the subgroup D virus, the mutant virus, and recombinant viruses with an increased mammal tropism phenotype were unstable at 42 degrees C. These results suggest that the mammal tropism of the SR-D strain is not related to altered receptor specificity but rather to an unstable and fusogenic viral glycoprotein. A temperature sensitivity phenotype for infectivity of mammalian cells was also observed for another mammal-tropic avian retrovirus, the Bratislava 77 strain of RSV, a subgroup C virus, but was not seen for any other avian retrovirus tested, strengthening the correlation between mammal tropism and temperature sensitivity.

Animals↗

A comparative study of criteria for subgrouping alcoholics: the primary/secondary diagnostic scheme versus variations of the type 1/type 2 criteria.

OBJECTIVE: This study compared three methods for identifying type 1 and type 2 alcoholism to determine how well the methods agree. It also evaluated the comparability of each of these schemes to the primary/secondary approach to subgrouping alcoholics. METHOD: Fifty male alcoholic inpatients were given diagnoses of primary alcoholism without antisocial personality disorder or primary antisocial personality disorder with secondary alcoholism on the basis of data from structured interviews. Operationalized criteria for type 1 and type 2 alcoholism from three groups of researchers (Gilligan et al., von Knorring et al., and Sullivan et al.) were also used to designate subgroups of the same subjects. RESULTS: Subgroups of subjects classified as having type 1 or type 2 alcoholism according to the criteria of von Knorring et al. and of Sullivan et al. showed good levels of agreement, but the criteria of Gilligan et al. yielded poor agreement with those of the other two schemes. Subgroups with type 1 or type 2 alcoholism according to the criteria of Sullivan et al. showed significant overlap with subgroups diagnosed according to the primary/secondary alcoholism scheme: there was 73% concordance between the type 1 subgroup and the subgroup with primary alcoholism and 73% concordance between the type 2 subgroup and the subgroup with primary antisocial personality disorder and secondary alcoholism. CONCLUSIONS: There is variability in assigning diagnoses of type 1 and type 2 alcoholism with the use of current methods. Also, type 1/type 2 classifications based primarily on age-at-onset factors significantly overlap with the primary/secondary classifications of alcoholics.

Adolescent↗

Multivariable risk prediction can greatly enhance the statistical power of clinical trial subgroup analysis.

BACKGROUND: When subgroup analyses of a positive clinical trial are unrevealing, such findings are commonly used to argue that the treatment's benefits apply to the entire study population; however, such analyses are often limited by poor statistical power. Multivariable risk-stratified analysis has been proposed as an important advance in investigating heterogeneity in treatment benefits, yet no one has conducted a systematic statistical examination of circumstances influencing the relative merits of this approach vs. conventional subgroup analysis. METHODS: Using simulated clinical trials in which the probability of outcomes in individual patients was stochastically determined by the presence of risk factors and the effects of treatment, we examined the relative merits of a conventional vs. a "risk-stratified" subgroup analysis under a variety of circumstances in which there is a small amount of uniformly distributed treatment-related harm. The statistical power to detect treatment-effect heterogeneity was calculated for risk-stratified and conventional subgroup analysis while varying: 1) the number, prevalence and odds ratios of individual risk factors for risk in the absence of treatment, 2) the predictiveness of the multivariable risk model (including the accuracy of its weights), 3) the degree of treatment-related harm, and 5) the average untreated risk of the study population. RESULTS: Conventional subgroup analysis (in which single patient attributes are evaluated "one-at-a-time") had at best moderate statistical power (30% to 45%) to detect variation in a treatment's net relative risk reduction resulting from treatment-related harm, even under optimal circumstances (overall statistical power of the study was good and treatment-effect heterogeneity was evaluated across a major risk factor [OR = 3]). In some instances a multi-variable risk-stratified approach also had low to moderate statistical power (especially when the multivariable risk prediction tool had low discrimination). However, a multivariable risk-stratified approach can have excellent statistical power to detect heterogeneity in net treatment benefit under a wide variety of circumstances, instances under which conventional subgroup analysis has poor statistical power. CONCLUSION: These results suggest that under many likely scenarios, a multivariable risk-stratified approach will have substantially greater statistical power than conventional subgroup analysis for detecting heterogeneity in treatment benefits and safety related to previously unidentified treatment-related harm. Subgroup analyses must always be well-justified and interpreted with care, and conventional subgroup analyses can be useful under some circumstances; however, clinical trial reporting should include a multivariable risk-stratified analysis when an adequate externally-developed risk prediction tool is available.

Clinical Trials as Topic↗

Clinical characteristics of respiratory syncytial virus (RSV) subgroup infections in Japan.

The subgroup characteristics of 130 strains of respiratory syncytial virus (RSV) isolated in Sapporo during 9 epidemic years 1980-1989 were determined. Monoclonal antibodies raised against the RSV Long strains were used. Subgroup A included 77 (59.2%) isolates and subgroup B 52 (40.0%) strains, while 1 strain was considered to be a variant of a subgroup A strain. The distribution by age of infants and children was different for the 2 subgroups: less than 1 year of age infants with subgroup A infection dominated, greater than 1 year of age subgroup A infections were less common than subgroup B infections. These was no difference in type of illness between the subgroups. Bronchiolitis was the dominant diagnosis in all patients.

Age Factors↗