Effect of growth rates on hormonal and pubertal status in Nellore heifers early weaned.

This study aimed to determine the effect of growth rates on the hormonal status and puberty onset. Forty-eight Nellore heifers were weaned at 3.0 ± 0.1 (means ± standard error of the mean) months old were blocked according to body weight at weaning (84 ± 2 kg) and randomly assigned to treatments. The treatments were arranged in 2 × 2 factorial according to the feeding program. The first program was high (H; 0.79 kg/day) or control (C; 0.45 kg/day) average daily gain (ADG) from 3rd to 7th month of age (growing phase I). The second program was also high (H; 0.70 kg/day) or control (C; 0.50 kg/day) ADG from the 7th month until puberty (growing phase II), resulting in four treatments: HH (n = 13), HC (n = 10), CH (n = 13), and CC (n = 12). To achieve desired gains, heifers in high ADG program were fed ad libitum dry matter intake (DMI), and the control group was offered around 50% of ad libitum DMI of high group. All heifers received a diet with similar composition. Puberty was assessed weekly by ultrasound examination, and the largest follicle diameter was evaluated every month. Blood samples were collected to quantify leptin, insulin growth factor-1 (IGF1) and luteinizing hormone (LH). At 7 months of age, heifers in high ADG were 35 kg heavier than the control. Heifers in the HH had greater DMI compared with CH in phase II. The puberty rate at 19 months old was greater in the HH treatment (84%) than in the CC (23%), but there was no difference between HC (60%) and CH (50%) treatments. Heifers from HH treatment had greater serum leptin concentration than others at 13 months old, and serum leptin was greater in HH compared with CH and CC at 18 months old. High heifers in phase I had greater serum IGF1 concentration than the control. In addition, HH heifers had a greater diameter of the largest follicle than CC. There was no interaction between phases and age in any variable relative to the LH profile. However, the heifers' age was the main factor that increased the frequency of LH pulse. In conclusion, increasing ADG was associated with greater ADG, serum leptin and IGF-1 concentration, and puberty onset; however, LH concentration was affected mainly by age of the animal. The increasing growth rate at younger age made heifers more efficient.

Effects of feeding 25-hydroxyvitamin D3 with an acidogenic diet during the prepartum period in dairy cows: Mineral metabolism, energy balance, and lactation performance of Holstein dairy cows.

Our objective was to determine the effects of feeding 25-hydroxyvitamin D3 [25(OH)D3], or vitamin D3 (cholecalciferol) on plasma, mineral, and metabolite concentrations, mineral balance, mineral excretion, rumination, energy balance, and milk production of dairy cows. We hypothesized that supplementing 3 mg/d of 25(OH)D3 during the prepartum period would be more effective than supplementing vitamin D3 at the National Research Council (2001) levels to minimize calcium imbalance during the transition period and improve milk production of dairy cows. Forty multiparous, pregnant nonlactating-Holstein cows were enrolled in this study. Body weight, body condition score, parity, and milk yield in the previous lactation (mean ± standard deviation) were 661 ± 59.2, 3.46 ± 0.35, 1.79 ± 0.87, and 33.2 ± 6.43 kg/d, respectively. Cows were enrolled into the blocks (n = 20 for each treatment) at 30 d of the expected day of calving to receive an acidogenic diet (373 g/kg of neutral detergent fiber and 136 g/kg of crude protein, dry matter basis; -110 mEq/kg) associated with the treatments: (1) control (CTRL), vitamin D3 at 0.625 mg/d (equivalent to 25,000 IU of vitamin D3/d) or (2) 25(OH)D3 at 3 mg/d (equivalent to 120,000 IU of vitamin D3/d). All cows were fed with the base ration for 49 d after calving. Blood samples were taken on d 7, 0, 1, 2, 21, and 42, relative to calving. No effect of treatment was observed for prepartum dry matter intake or body condition score. A trend for increase of ionized Ca was observed for the cows fed 25(OH)D3, compared with the CTRL, but no effect of treatment was detected for total Ca or total P. Feeding 25(OH)D3 increased colostrum yield. The plasmatic concentration of 25-hydroxyvitamin D3 was increased with 25(OH)D3 supplementation. 25-Hydroxyvitamin D3 supplementation increased plasma glucose concentration at parturition. The postpartum dry matter intake was not influenced by treatments. Feeding 25(OH)D3 increases milk yield, 3.5% fat-corrected milk, and energy-corrected milk and improves milk yield components in early lactation. Overall, these findings suggest that 25(OH)D3 at 3 mg/d can improve the energy metabolism and lactation performance, compared with the current-feeding practice of supplementing vitamin D3 at 0.625 mg/d.

Performance, health, and physiological responses of newly received feedlot cattle supplemented with pre- and probiotic ingredients.

Nutritional strategies that optimize immunity of feedlot cattle are warranted due to increasing regulations with the use of feed-grade antimicrobials. This study evaluated physiological, health, and performance responses of cattle receiving a synbiotic supplement (yeast-derived prebiotic + Bacillus subtilis probiotic), which replaced feed-grade antimicrobials or were fed in conjunction with monensin during the initial 45 days in the feedlot. Angus-influenced steers (n = 256) were acquired from an auction facility on day -2, and transported (800 km) to the feedlot. Shrunk BW was recorded upon arrival (day -1). Steers were allocated to 1 of 18 pens (day 0), and pens were assigned to receive (n = 6/treatment) a free-choice diet containing: (1) monensin and tylosin (RT; 360 mg/steer daily from Rumensin and 90 mg/steer daily from Tylan; Elanco Animal Health, Greenfield, IN, USA), (2) yeast-derived ingredient and B. subtilis probiotic (CC; 18 g/steer daily of Celmanax and 28 g/steer daily of Certillus; Church and Dwight Co., Inc., Princeton, NJ, USA), or (3) monensin in addition to yeast-derived and B. subtilis ingredients (RCC) as in RT and CC. Steers were assessed for bovine respiratory disease (BRD) and DMI daily. Steer BW was recorded on days 45 and 46, and averaged for final BW. Blood samples were collected on days 0, 7, 17, 31, and 45. Feed intake was greater (P ≤ 0.05) in CC vs. RCC and RT during the initial 3 weeks upon feedlot arrival. No treatment differences were noted (P ≥ 0.41) for average daily gain, BW, and feed efficiency. Incidence of BRD did not differ (P = 0.77) between treatments (average 80.1%). A greater proportion (P ≤ 0.03) of RT steers diagnosed with BRD required a second antimicrobial treatment compared with CC and RCC (57.3, 37.3, and 38.6%, respectively). Removal of steers from the trial due to severe morbidity + mortality was greater (P = 0.02) in RT vs. CC (22.4 and 7.0%), and did not differ (P ≥ 0.16) among RCC (12.9%) vs. RT and CC. Plasma glucose concentrations were greater (P ≤ 0.02) in CC vs. RCC and RT on day 7. Plasma concentrations of nonesterified fatty acids were greater (P ≤ 0.02) in RT and RCC vs. CC on day 7, and in RT vs. CC on day 17. Steers receiving the synbiotic supplement had improved response to BRD treatment, suggesting heightened immunocompetence from partially enhanced metabolism and the nutraceutical effects of B. subtilis and yeast compounds.

Flint corn grain processing and citrus pulp level in finishing diets for feedlot cattle.

Four trials were conducted to evaluate the effects of flint corn processing and the replacement of corn with citrus pulp (CiP) in diets for Nellore feedlot cattle. In a 103-d finishing trial, 216 Nellore bulls (350 ± 24 kg initial BW) were used in a randomized complete block design with a 2 × 4 factorial arrangement of treatments. Factors included 2 processing methods, either ground corn (GC) or steam-flaked corn (FC), with CiP replacing each corn type at 4 levels (0, 25, 50, and 75% of DM). All diets contained 12% sugarcane bagasse and 88% concentrate (DM basis). Treatments were also evaluated in metabolism trials, in which 10 ruminally cannulated Nellore steers (389 ± 37 kg) were assigned to 2 independent but simultaneous 5 × 5 Latin squares, each using 1 method of corn processing (GC and FC). Interactions ( < 0.05) between corn processing and CiP inclusion level were observed for final BW, DMI, ADG, G:F, and HCW. With FC-based diets, added CiP linearly decreased final BW ( = 0.04), whereas with GC-based diets, added CiP quadratically increased final BW ( = 0.002). With FC-based diets, the inclusion of CiP linearly increased DMI ( = 0.03) and linearly decreased ADG ( = 0.03) and G:F ( = 0.001). Increasing CiP in GC-based diets quadratically increased DMI ( = 0.001), ADG ( = 0.005), and HCW ( = 0.003). In FC-based diets, CiP inclusion had no effect on HCW ( = 0.21). Dressing percent, LM area, and 12th-rib fat were not affected by diet ( ≥ 0.05). For steers fed GC diets, CiP inclusion in the diet quadratically decreased the molar proportion of isovalerate ( = 0.001) but linearly increased ruminal butyrate ( = 0.006). No differences ( ≥ 0.16) were observed for total VFA concentrations, acetate:propionate ratio, and ruminal NH-N as CiP replaced GC. For steers fed FC diets, the molar proportion of acetate linearly increased ( = 0.002) whereas the proportion of propionate was linearly decreased ( < 0.001), resulting in a linear increase ( = 0.001) in the acetate:propionate ratio. Replacing corn with CiP linearly reduced NEm ( = 0.001) and NEg ( < 0.001) of FC-based diets but did not affect ( = 0.15) NE values of CG-based diets. Steam flaking flint corn improved cattle performance in this trial more than has been reported for dent corn in the published literature.

Changes in epidemiology of rotavirus in the Triângulo Mineiro region of Brazil: lack of two consecutive rotavirus seasons

Rotaviruses are the main cause of infantile acute diarrhea, and a monovalent (G1P[8]) vaccine against the virus was introduced into the Brazilian National Immunization Program for all infants in March 2006. The objectives of this study were to determine the rate and genotype distribution of rotavirus causing infantile diarrhea in the Triângulo Mineiro region of Brazil during 2011-2012 and to assess the impact of local vaccination. Fecal specimens were analyzed for detection and characterization of rotavirus using polyacrylamide gel electrophoresis, reverse transcription followed by polymerase chain reaction (PCR), and PCR-genotyping assays. Overall, rotavirus was diagnosed in 1.7% (6/348) of cases. Rotavirus positivity rates decreased 88% [95% confidence intervals (CI)=15.2, 98.3%; P=0.026] in 2011 and 78% (95%CI=30.6, 93.0%; P=0.007) in 2012 when compared with available data for baseline years (2005/2006) in Uberaba. In Uberlândia, reductions of 95.3% (95%CI=66.0, 99.4%; P=0.002) in 2011, and 94.2% (95%CI=56.4, 99.2%; P=0.004) in 2012 were also observed compared with data for 2008. The circulation of rotavirus G2P[4] strains decreased during the period under study, and strains related to the P[8] genotype reemerged in the region. This study showed a marked and sustained reduction of rotavirus-related cases, with a lack of rotavirus in the 2011 and 2012 seasons, suggesting a positive impact of the vaccination program.

Changes in epidemiology of rotavirus in the Triângulo Mineiro region of Brazil: lack of two consecutive rotavirus seasons.

Rotaviruses are the main cause of infantile acute diarrhea, and a monovalent (G1P[8]) vaccine against the virus was introduced into the Brazilian National Immunization Program for all infants in March 2006. The objectives of this study were to determine the rate and genotype distribution of rotavirus causing infantile diarrhea in the Triângulo Mineiro region of Brazil during 2011-2012 and to assess the impact of local vaccination. Fecal specimens were analyzed for detection and characterization of rotavirus using polyacrylamide gel electrophoresis, reverse transcription followed by polymerase chain reaction (PCR), and PCR-genotyping assays. Overall, rotavirus was diagnosed in 1.7% (6/348) of cases. Rotavirus positivity rates decreased 88% [95% confidence intervals (CI)=15.2, 98.3%; P=0.026] in 2011 and 78% (95%CI=30.6, 93.0%; P=0.007) in 2012 when compared with available data for baseline years (2005/2006) in Uberaba. In Uberlândia, reductions of 95.3% (95%CI=66.0, 99.4%; P=0.002) in 2011, and 94.2% (95%CI=56.4, 99.2%; P=0.004) in 2012 were also observed compared with data for 2008. The circulation of rotavirus G2P[4] strains decreased during the period under study, and strains related to the P[8] genotype reemerged in the region. This study showed a marked and sustained reduction of rotavirus-related cases, with a lack of rotavirus in the 2011 and 2012 seasons, suggesting a positive impact of the vaccination program.

Radon dose assessment in underground mines in Brazil.

Underground miners are internally exposed to radon, thoron and their short-lived decay products during the mineral processing. There is also an external exposure due to the gamma emitters present in the rock and dust of the mine. However, the short-lived radon decay products are recognised as the main radiation health risk. When inhaled, they are deposited in the respiratory system and may cause lung cancer. To address this concern, concentration measurements of radon and its progeny were performed, the equilibrium factor was determined and the effective dose received was estimated in six Brazilian underground mines. The radon concentration was measured by using E-PERM, AlphaGUARD and CR-39 detectors. The radon progeny was determined by using DOSEman. The annual effective dose for the miners was estimated according to United Nations Scientific Committee on the Effects of Atomic Radiation methodologies. The mean value of the equilibrium factor was 0.4. The workers' estimated effective dose ranged from 1 to 21 mSv a(-1) (mean 9 mSv a(-1)).

Energy efficiency of growing ram lambs fed concentrate-based diets with different roughage sources.

Poor-quality roughages are widely used as fiber sources in concentrate-based diets for ruminants. Because roughage quality is associated with the efficiency of energy use in forage-based diets, the objective of this study was to determine whether differing the roughage source in concentrate-based diets could change the energy requirements of growing lambs. Eighty-four 1/2 Dorper × 1/2 Santa Inês ram lambs (18.0 ± 3.3 kg BW) were individually penned and divided into 2 groups according to primary source of dietary roughage: low-quality roughage (LQR; sugarcane bagasse) or medium-quality roughage (MQR; coastcross hay). Diets were formulated to be isonitrogenous (2.6% N) and to meet 20% of physically effective NDF. After a 10-d ad libitum adaptation period, 7 lambs from each group were randomly selected and slaughtered (baseline). Twenty-one lambs in each diet group were fed ad libitum and slaughtered at 25, 35, or 45 kg BW. The remaining 28 lambs (14 from each diet group) were submitted to 1 of 2 levels of feed restriction: 70% or 50% of the ad libitum intake. Retentions of body fat, N, and energy were determined. Additionally, 6 ram lambs (44.3 ± 5.6 kg BW) were kept in metabolic cages and used in a 6 × 6 Latin square experiment designed to establish the ME content of the 2 diets at the 3 levels of DM intake. There was no effect of intake level on diet ME content, but it was greater in the diet with LQR than in the diet with MQR (3.18 vs. 2.94 Mcal/kg, respectively; P < 0.01). Lambs fed the diet with LQR had greater body fat (g/kg of empty BW) and energy concentrations (kcal/kg of empty BW) because of a larger visceral fat deposition (P < 0.05). Using a low-quality roughage as a primary source of forage in a concentrate-based diet for growing lambs did not change NEm and the efficiency of ME use for maintenance, which averaged 71.6 kcal/kg(0.75) of shrunk BW and 0.63, respectively. On the other hand, the greater nonfibrous carbohydrate content of the diet with LQR resulted in a 17% better efficiency of ME use for gain (P < 0.01), which was associated with a greater partial efficiency of energy retention as fat (P < 0.01). This increased nutritional efficiency, however, should be viewed with caution because it is related to visceral fat deposition, a nonedible tissue.

Are cats (Felis catus) from multi-cat households more stressed? Evidence from assessment of fecal glucocorticoid metabolite analysis.

Given the social and territorial features described in feral cats, it is commonly assumed that life in multi-cat households is stressful for domestic cats and suggested that cats kept as single pets are likely to have better welfare. On the other hand, it has been hypothesized that under high densities cats can organize themselves socially thus preventing stress when spatial dispersion is unavailable. This study was aimed at comparing the general arousal underpinning emotional distress in single housed cats and in cats from multi-cat households (2 and 3-4 cats) on the basis of fecal glucocorticoid metabolites (GCM) measured via enzyme immunoassay (EIA). GCM did not significantly vary as a function of living style (single, double or group-housing); highly stressed individuals were equally likely in the three groups. Young cats in multi-cat households had lower GCM, and overall cats that tolerate (as opposed to dislike) petting by the owners tended to have higher GCM levels. Other environmental aspects within cat houses (e.g. relationship with humans, resource availability) may play a more important role in day to day feline arousal levels than the number of cats per se.

Distribution of rotavirus genotypes after vaccine introduction in the Triângulo Mineiro region of Brazil: 4-Year follow-up study.

BACKGROUND: Rotaviruses are the major cause of diarrhea in children for which a monovalent G1P[8] vaccine has been provided free for all Brazilian infants since March 2006. OBJECTIVES: To investigate prevalence and genotypes of rotavirus strains causing diarrhea in children in Triângulo Mineiro, Minas Gerais, during 2007-2010, and to assess local vaccine impact. STUDY DESIGN: Fecal specimens were analyzed for rotavirus detection and characterization by PAGE, RT-PCR and PCR-genotyping assays. RESULTS: Overall, rotavirus was diagnosed in 12.1% (76/630) cases, accounting for 35.8% of the hospitalizations and 6.5% of outpatient attendance due to diarrhea. A trend in rotavirus disease reduction occurred in both cities (71.8% and 83.4% in Uberaba; 95.3% in Uberlândia) up to 2009, but it reversed in 2010 with increased rotavirus cases in Uberlândia. Short pattern G2P[4] strains were detected in all but three (96%) cases of mixed/P[NT] infections with long electropherotypes. CONCLUSIONS: This 4-year follow-up study showed a reduction in rotavirus-related diarrhea and even skipped a rotavirus season, which is consistent with vaccine mediated protection. The 2007-2010 rotavirus epidemic curve reflected the natural cyclic fluctuation of the single G2P[4] genotype, with sharp reduction of cases in 2008 leading to lack of a rotavirus 2009 season (both cases and hospitalizations) followed by its come back in 2010. Diarrhea cases related to either vaccine serotype/genotype (G1 or P[8]) were not detected. Thus, a new scenario emerged with a single epidemic genotype replacing the cocirculation of great diversity of genotypes, thus far, a hallmark of the epidemiology of rotavirus in Brazil.

Rotavirus-associated infantile diarrhea in Uberaba, Minas Gerais, on the wake of the Brazilian vaccination program.

BACKGROUND: Rotaviruses are major causes of diarrhea in children for which vaccines were developed and are currently in use. OBJECTIVES: To investigate the genotypes of rotavirus strains causing dehydrating diarrhea in children in Uberaba, Triângulo Mineiro region, Minas Gerais, during 2005-2006. METHODS: Rotavirus-associated diarrhea was investigated in fecal specimens by PAGE and strains were characterized for their genotype by RT-PCR and PCR-typing assays. RESULTS: Rotavirus was detected in 15% (39/260) of the fecal specimens by PAGE: 64% of the specimens presented short electrophoretic patterns and G2P[4] genotype; and 36% presented long electropherotypes and G1P[8], G9P[8], G4P[9] and two strains with sill undetermined G and P[8] genotype. A change in the dominant electrophoretic pattern was observed, shifting from long to short patterns and coinciding with the highest incidence of diarrheal cases. CONCLUSIONS: Those are the first data on rotavirus strains circulating in the Triângulo Mineiro region. They were obtained over a 16-month period that included the first 10 months after the launch of the national rotavirus immunization program that uses a monovalent G1P[8] attenuated vaccine strain. These results should further our understanding of the dynamics of rotavirus strains and help interpreting the significance of the program.

The emergence of YMDD mutants precedes biochemical flare by 19 weeks in lamivudine-treated chronic hepatitis B patients: an opportunity for therapy reevaluation

Given the loss of therapeutic efficacy associated with the development of resistance to lamivudine (LMV) and the availability of new alternative treatments for chronic hepatitis B patients, early detection of viral genotypic resistance could allow the clinician to consider therapy modification before viral breakthrough and biochemical relapse occur. To this end, 28 LMV-treated patients (44 ± 12 years; 24 men), on their first therapy schedule, were monitored monthly at four Brazilian centers for the emergence of drug resistance using the reverse hybridization-based INNO-LiPA HBV DR assay and occasionally sequencing (two cases). Positive viral responses (HBV DNA clearance) after 6, 12, and 18 months of therapy were achieved by 57, 68, and 53 percent of patients, while biochemical responses (serum alanine aminotransferase normalization) were observed in 82, 82, and 53 percent of cases. All viral breakthrough cases (N = 8) were related to the emergence of YMDD variants observed in 7, 21, and 35 percent of patients at 6, 12, and 18 months, respectively. The emergence of these variants was not associated with viral genotype, HBeAg expression status, or pretreatment serum alanine aminotransferase levels. The detection of resistance-associated mutations was observed before the corresponding biochemical flare (41 ± 14 and 60 ± 15 weeks) in the same individuals. Then, if highly sensitive LMV drug resistance testing is carried out at frequent and regular intervals, the relatively long period (19 ± 2 weeks) between the emergence of viral resistance and the onset of biochemical relapse can provide clinicians with ample time to re-evaluate drug therapy.

The emergence of YMDD mutants precedes biochemical flare by 19 weeks in lamivudine-treated chronic hepatitis B patients: an opportunity for therapy reevaluation.

Given the loss of therapeutic efficacy associated with the development of resistance to lamivudine (LMV) and the availability of new alternative treatments for chronic hepatitis B patients, early detection of viral genotypic resistance could allow the clinician to consider therapy modification before viral breakthrough and biochemical relapse occur. To this end, 28 LMV-treated patients (44 +/- 12 years; 24 men), on their first therapy schedule, were monitored monthly at four Brazilian centers for the emergence of drug resistance using the reverse hybridization-based INNO-LiPA HBV DR assay and occasionally sequencing (two cases). Positive viral responses (HBV DNA clearance) after 6, 12, and 18 months of therapy were achieved by 57, 68, and 53% of patients, while biochemical responses (serum alanine aminotransferase normalization) were observed in 82, 82, and 53% of cases. All viral breakthrough cases (N = 8) were related to the emergence of YMDD variants observed in 7, 21, and 35% of patients at 6, 12, and 18 months, respectively. The emergence of these variants was not associated with viral genotype, HBeAg expression status, or pretreatment serum alanine aminotransferase levels. The detection of resistance-associated mutations was observed before the corresponding biochemical flare (41 +/- 14 and 60 +/- 15 weeks) in the same individuals. Then, if highly sensitive LMV drug resistance testing is carried out at frequent and regular intervals, the relatively long period (19 +/- 2 weeks) between the emergence of viral resistance and the onset of biochemical relapse can provide clinicians with ample time to re-evaluate drug therapy.

Effect of intragenic rearrangement and changes in the 3' consensus sequence on NSP1 expression and rotavirus replication.

The nonpolyadenylated mRNAs of rotavirus are templates for the synthesis of protein and the segmented double-stranded RNA (dsRNA) genome. During serial passage of simian SA11 rotaviruses in cell culture, two variants emerged with gene 5 dsRNAs containing large (1.1 and 0.5 kb) sequence duplications within the open reading frame (ORF) for NSP1. Due to the sequence rearrangements, both variants encoded only C-truncated forms of NSP1. Comparison of these and other variants encoding defective NSP1 with their corresponding wild-type viruses indicated that the inability to encode authentic NSP1 results in a small-plaque phenotype. Thus, although nonessential, NSP1 probably plays an active role in rotavirus replication in cell culture. In determining the sequences of the gene 5 dsRNAs of the SA11 variants and wild-type viruses, it was unexpectedly found that their 3' termini ended with 5'-UGAACC-3' instead of the 3' consensus sequence 5'-UGACC-3', which is present on the mRNAs of nearly all other group A rotaviruses. Cell-free assays indicated that the A insertion into the 3' consensus sequence interfered with its ability to promote dsRNA synthesis and to function as a translation enhancer. The results provide evidence that the 3' consensus sequence of the gene 5 dsRNAs of SA11 rotaviruses has undergone a mutation causing it to operate suboptimally in RNA replication and in the expression of NSP1 during the virus life cycle. Indeed, just as rotavirus variants which encode defective NSP1 appear to have a selective advantage over those encoding wild-type NSP1 in cell culture, it may be that the atypical 3' end of SA11 gene 5 has been selected for because it promotes the expression of lower levels of NSP1 than the 3' consensus sequence.

Molecular characterization of porcine rotaviruses from the southern region of Brazil: characterization of an atypical genotype G[9] strain.

The G (VP7) and P (VP4) serotype distribution of Brazilian porcine rotaviruses was determined using reverse transcription-PCR genotyping methods. Common porcine G types G3, G4, and G5 were detected in combination with P types [6] and [7]. The detection of nonporcine G types and unusual G-P combinations and the characterization of an atypical virus indicated that interspecies transmission may contribute to the genetic diversity of porcine rotaviruses.

The stability of porcine rotavirus in feces.

Rotaviruses are known as major causal agents of diarrhea in humans and animals. They affect young animals in intensive rearing and cause great economic losses. This study evaluated the infectivity of porcine rotavirus maintained for 32 months at approximately 10 degrees C in the original stool specimens. Thirty stool specimens of 1-4-week-old piglets from breeding farms located in the southwest of the State of Parana were selected for this study. They were randomly chosen from stool samples positive for rotavirus RNA by polyacrylamide gel electrophoresis (PAGE) at the time of collection. The thirty stool samples maintained for 32 months were re-tested by PAGE and 11 out of 30 were still positive showing physical integrity of the eleven segments of viral RNA. In order to demonstrate the maintenance of viral infectivity processed fecal homogenates were inoculated in MA-104 cell cultures. After an average of three blind passages 5 out of 11 samples demonstrated cytopathic effect similar to that of a simian rotavirus (SA-11) used as positive control. To confirm these findings an immunofluorescence test was performed and typical cytoplasmatic granular fluorescence was observed. Electron microscopy of stool samples showed that most of the virus particles were single-shelled and some were found to be in advanced state of degradation. The viral nucleic acid extracted from six fecal specimens out of those that showed physical integrity of rotavirus RNA by PAGE were also amplified when submitted to RT-PCR demonstrating stability of viral RNA. We therefore concluded that porcine rotavirus infectivity is maintained for a long period of time in stool specimens at low temperature.

Detection of porcine rotavirus type G9 and of a mixture of types G1 and G5 associated with Wa-like VP4 specificity: evidence for natural human-porcine genetic reassortment.

Rotavirus type G5 is a primarily porcine pathogen that has caused frequent and widespread diarrhea in children in Brazil and in piglets elsewhere. Initial results on the rotavirus types circulating in diarrheic piglets in Brazil disclosed a high diversity of strains with distinct G types including G1, G4, G5, and G9 and the novelty of P[8], the predominant human P specificity type. Those results add strong evidence for the emergence of new strains through natural reassortment between rotaviruses of human and porcine origins.

Identification of two lineages (WA-like and F45-like) within the major rotavirus genotype P[8].

The fourth gene of a porcine (S8) and eight human rotavirus isolates possessing the major human VP4 specificity (P1A serotype and/or P[8] genotype) were partially sequenced and compared to other available P[8] sequences from rotaviruses types G1, G3, G5 and G9 specificities which had been originally recovered from children with diarrhea in Japan, Brazil and the USA. Brazilian rotavirus S8 represented the single known porcine rotavirus with this P specificity. Phylogenetic analysis revealed two lineages or subgenotypes within P[8] strains: the F45-like P subgenotype comprised most of the strains, including all the human G5 isolates analyzed, whereas the Wa- or S8-like subgenotype consisted of only a human isolate obtained in the same geographic region as S8 and an American strain with atypical RNA profile besides the prototypes Wa and S8 viruses. A conserved basic amino acid residue at position 131 in VP4 seemed characteristic of the F45-like P[8] subgenotype.