Effect of broiler breeders fed with corn or sorghum diet and canthaxanthin supplementation on production and reproductive performance.

This study was designed to evaluate the effect of corn or sorghum diet and canthaxanthin (CX) supplementation on performance in broiler breeders. A total of 440 females with similar body weight (BW) (3.71 ± 0.14 kg) and 60 roosters were placed in an open-sided house with 20 pens, randomly distributed in a factorial arrangement (2 × 2). There were 4 diets of 2 ingredients; corn (CO) or sorghum (SO) and 2 levels of CX; 6 mg/kg (CX) and 0 mg/kg (NCX) totaling 5 replicate pens of 22 females and 3 males each, from 42 to 65 wk, divided in 2 periods (from wk 42 to 53 and wk 54 to 65). Birds' BW was measured every 28 d and mortality rate was calculated at the end of trial. Egg production (%), egg specific gravity (g/cm3), egg weight (g), yolk weight (%), albumen weight (%), eggshell weight (%) and yolk colorimetric score were measured weekly. Incubation parameters were recorded in 12 incubations to evaluate hatching eggs, hatching (%), hatchability (%), fertility (%), weight of the chicks born and their quality. The BW, mortality, percentage of yolk and albumen weight, fertility and some incubation parameters were not affected (P > 0.05) by diets used. An increase in the egg production, hatching eggs, chicks born and first quality chick by hen at the second period were observed in CX breeder's diets (P = 0.0066; P = 0.0060; P = 0.0368; P = 0.0326). Egg specific gravity and eggshell weight were improved at the first period by SO+CX diet (P = 0.0138; P = 0.0209) and the same effect to egg weight, but at the second period (P = 0.0251). The CX was well absorbed from the diet and effectively transferred to the egg yolk, thereby increasing egg yolk pigmentation in the both periods (P < 0.0001). The CX supplementation in broiler breeder diets improved the productive and reproductive performance (laying% and hatchable eggs) at the second period, also to the both periods improved the egg yolk pigmentation.

Effect of broiler breeders fed with corn or sorghum and canthaxanthin on lipid peroxidation, fatty acid profile of hatching eggs, and offspring performance.

The aim of study was to evaluate the effect on broiler breeders fed with corn or sorghum diets and canthaxanthin on lipid peroxidation, fatty acid, and offspring's performance. A total of 440 females with similar body weight (BW) (3.77 ± 0.11 kg) and 60 roosters were placed in an open-sided house with 20 pens, randomly distributed in a factorial arrangement (2 × 2). There were 4 diets of 2 ingredients; corn (CO) or sorghum (SO) and 2 levels of canthaxanthin; 6 mg/kg (CX) and 0 mg/kg (NCX) totaling five replicate pens of 22 females and 3 males each, from 45 to 65 wk old. The BW was measured every 28 days, carotenoid concentration, thiobarbituric acid reactive substances (TBARS), fatty acid profile (%) in egg yolks, and the performance from two incubations and their offspring were evaluated. The study had the same statistical design as broiler breeders, making a total of 4 groups with 10 replicate pens of 8 chicks each. The BW and mortality were not affected (P > 0.05) by diets. Egg yolks coming from the CO diet had the highest (P < 0.05) lutein (3.8 vs. 0.49 mg/kg) and zeaxanthin (4.25 vs. 0.22 mg/kg) concentration compared to SO diet. The SO+CX diet had the highest CX concentration (P < 0.0001). The SO+CX diet showed the lowest TBARS (P = 0.0002) in the egg yolk compared to the CO+CX diet. Egg yolks coming from breeders fed with CO showed a higher concentration of saturated fatty acids (23.36 vs. 21.44%) and monounsaturated fatty acids (27.17 vs. 24.96%). Egg yolks arising from broiler breeders fed with SO diets showed a higher concentration of polyunsaturated fatty acids compared (15.29 vs. 12.88%). The CX reduced the offspring CO diets mortality and improved their viability at 64 wk-old for the broiler breeders (P < 0.05). CX was well absorbed from the diet and effectively transferred to the egg yolk, thereby increasing its concentration in the yolk. This conferred resistance to oxidative stress to the yolk and also later to the developing embryo and its ultimate performance.

Energy potential and alternative usages of biogas and sludge from UASB reactors: case study of the Laboreaux wastewater treatment plant.

This work assessed the energy potential and alternative usages of biogas and sludge generated in upflow anaerobic sludge blanket reactors at the Laboreaux sewage treatment plant (STP), Brazil. Two scenarios were considered: (i) priority use of biogas for the thermal drying of dehydrated sludge and the use of the excess biogas for electricity generation in an ICE (internal combustion engine); and (ii) priority use of biogas for electricity generation and the use of the heat of the engine exhaust gases for the thermal drying of the sludge. Scenario 1 showed that the electricity generated is able to supply 22.2% of the STP power demand, but the thermal drying process enables a greater reduction or even elimination of the final volume of sludge to be disposed. In Scenario 2, the electricity generated is able to supply 57.6% of the STP power demand; however, the heat in the exhaust gases is not enough to dry the total amount of dehydrated sludge.

Seroepidemiology of selected alphaviruses and flaviviruses in bats in Trinidad.

A serosurvey of antibodies against selected flaviviruses and alphaviruses in 384 bats (representing 10 genera and 14 species) was conducted in the Caribbean island of Trinidad. Sera were analysed using epitope-blocking enzyme-linked immunosorbent assays (ELISAs) specific for antibodies against West Nile virus (WNV), Venezuelan equine encephalitis virus (VEEV) and eastern equine encephalitis virus (EEEV), all of which are zoonotic viruses of public health significance in the region. Overall, the ELISAs resulted in the detection of VEEV-specific antibodies in 11 (2.9%) of 384 bats. Antibodies to WNV and EEEV were not detected in any sera. Of the 384 sera, 308 were also screened using hemagglutination inhibition assay (HIA) for antibodies to the aforementioned viruses as well as St. Louis encephalitis virus (SLEV; which also causes epidemic disease in humans), Rio Bravo virus (RBV), Tamana bat virus (TABV) and western equine encephalitis virus (WEEV). Using this approach, antibodies to TABV and RBV were detected in 47 (15.3%) and 3 (1.0%) bats, respectively. HIA results also suggest the presence of antibodies to an undetermined flavivirus(es) in 8 (2.6%) bats. Seropositivity for TABV was significantly (P<0.05; χ2) associated with bat species, location and feeding preference, and for VEEV with roost type and location. Differences in prevalence rates between urban and rural locations were statistically significant (P<0.05; χ2) for TABV only. None of the aforementioned factors was significantly associated with RBV seropositivity rates.

Efficacy of a Brazilian calcium montmorillonite against toxic effects of dietary aflatoxins on broilers reared to market weight.

1. The protective effect of a natural Brazilian calcium montmorillonite (CaMont) against aflatoxins was studied in broiler chickens. 2. A total of 1056-d-old Cobb male broilers were housed in experimental pens (22 chickens per pen) for 42 d. Three levels of CaMont (0, 2.5 and 5 g/kg) and two levels of aflatoxins (0 and 3 mg/kg) were assayed. Each treatment had 8 replicate pens of 22 broiler chickens each. 3. Of all the chickens tested in the experiment, the ones treated with aflatoxins were the most adversely affected. CaMont treatment at concentrations of 2.5 and 5 g/kg improved body weight of chickens at 42 d of age by 13.3% and 22.7%, increased daily feed intake by 9.7% and 24.7%, and improved the productive efficiency index of chickens by 53% and 66.5%, respectively. 4. Dietary CaMont positively affected parameters such as weight of liver, heart and gizzard; however, serum potassium concentration decreased by 15.3% compared with that of chickens given only the aflatoxin-contaminated diet. 5. CaMont did not cause adverse effects in chickens that did not receive aflatoxins. 6. CaMont at pH 8.5 partially reduced the toxic effects of aflatoxins in broilers when included at levels of 2.5 and 5 g/kg in the diet.

Amaranth 7S globulin Langmuir films and its interaction with l-α-dipalmitoilphosphatidilcholine at the air-fluid interface.

Amaranth seeds are one of the more promising food ingredients, due to their high protein content, among which the most important are storage proteins known as globulins. However, little is known about the physicochemical of the globulin proteins. In this work, we study the physicochemical behavior of films made of amaranth 7S globulin and its interaction with a model membrane made of L-α-dipalmitoylphosphatidylcholine (L-α-DPPC) at the air-liquid interface. The study was done by means of Langmuir balance, Brewster angle microscopy (BAM), fluorescence microscopy, and atomic force microscopy (AFM). We found that isotherms of pure 7S globulin directly deposited on either water or buffer subphases behave similarly and globulin forms a condensed film made of globular and denature structures, which was confirmed by BAM observations. Good mixtures of the protein with L-α-DPPC are formed at low surface pressure. However, they phase separate from moderate to high surface pressure as observed by BAM. Isotherms detect the presence of the protein in the mixture with L-α-DPPC, but we were unable to detect it through BAM or AFM. We show that fluorescence microscopy is a very good technique to detect the presence of the protein when it is well-mixed within the LE phase of the lipid. AFM images clearly show the formation of protein mono- and multilayers, and in phase mode, we detected domains that are formed by protein and LE lipid phase, which were corroborated by fluorescence microscopy. We have shown that globulin 7S mix well with lipid phases, which could be important in food applications as stabilizers or emulsifiers, but we also show that they can phase separate with a moderate to high surface pressure.

Effects of canthaxanthin on the productive and reproductive performance of broiler breeders.

The effects of supplementing canthaxanthin on productive and reproductive aspects of broiler breeders were examined in this study. In total, 360 female pullets and 36 roosters were placed in an open-sided house with 12 pens, each pen with an area of 7.0 m(2) (3.5 × 2.0 m). At 42 wk of age, the breeder hens and roosters were distributed into 2 experimental groups with similar BW and uniformity. From 46 to 66 wk of age, one group received 6 mg/kg of canthaxanthin supplemented in the diet and the other group received the diet without the addition of canthaxanthin (control diet). Body weight was measured every 28 d, the laying rate was calculated weekly, and mortality was evaluated at the end of the study. Twenty-one weekly incubations were performed to evaluate fertility and incubation responses. To evaluate the antioxidant effect of canthaxanthin at different storage times and during the incubation process, eggs from each treatment were subject to thiobarbituric reactive substances analysis. Body weight, mortality, and laying rate were not affected by the inclusion of canthaxanthin in the breeder's diets. An increase in hatchability of total and fertile eggs (P ≤ 0.0001 and P ≤ 0.0003, respectively) in breeders fed canthaxanthin during the experimental period was observed. Canthaxanthin also improved breeder fertility and reduced embryo mortality. This can be attributed to reductions in embryo mortality in the first 48 h of incubation and in the last wk of incubation. No differences were observed in BW and quality of the chicks. A reduction of thiobarbituric reactive substances was observed in yolks from stored hatching eggs produced by breeders fed diets plus canthaxanthin. The same effect was observed in yolks of eggs stored for 4 d and incubated for 7 d. The supplementation of broiler breeder diets with canthaxanthin improved the hatchability rate, fertility, and reduced the presence of thiobarbituric reactive substances in eggs.

Water stress induces up-regulation of DOF1 and MIF1 transcription factors and down-regulation of proteins involved in secondary metabolism in amaranth roots (Amaranthus hypochondriacus L.).

Roots are the primary sites of water stress perception in plants. The aim of this work was to study differential expression of proteins and transcripts in amaranth roots (Amaranthus hypochondriacus L.) when the plants were grown under drought stress. Changes in protein abundance within the roots were examined using two-dimensional electrophoresis and LC/ESI-MS/MS, and the differential expression of transcripts was evaluated with suppression subtractive hybridisation (SSH). Induction of drought stress decreased relative water content in leaves and increased solutes such as proline and total soluble sugars in roots. Differentially expressed proteins such as SOD(Cu-Zn) , heat shock proteins, signalling-related and glycine-rich proteins were identified. Up-regulated transcripts were those related to defence, stress, signalling (Ser, Tyr-kinases and phosphatases) and water transport (aquaporins and nodulins). More noteworthy was identification of the transcription factors DOF1, which has been related to several plant-specific biological processes, and MIF1, whose constitutive expression has been related to root growth reduction and dwarfism. The down-regulated genes/proteins identified were related to cell differentiation (WOX5A) and secondary metabolism (caffeic acid O-methyltransferase, isoflavone reductase-like protein and two different S-adenosylmethionine synthetases). Amaranth root response to drought stress appears to involve a coordinated response of osmolyte accumulation, up-regulation of proteins that control damage from reactive oxygen species, up-regulation of a family of heat shock proteins that stabilise other proteins and up-regulation of transcription factors related to plant growth control.

Tryptic amaranth glutelin digests induce endothelial nitric oxide production through inhibition of ACE: antihypertensive role of amaranth peptides.

Amaranth seed proteins have a better balance of essential amino acids than cereals and legumes. In addition, the tryptic hydrolysis of amaranth proteins generates, among other peptides, angiotensin converting enzyme (ACE) inhibitory (ACEi) peptides. ACE converts angiotensin I (Ang I) into Ang II, but is also responsible for the degradation of bradykinin (BK). In contrast to Ang II, BK stimulates vasodilation modulated through endothelial nitric oxide (NO) production. The aim of the present study was to characterize the ACEi activity of amaranth trypsin-digested glutelins (TDGs) and their ability to induce endothelial NO production. An IC(50) value of 200microgml(-1) was measured for TDG inhibition of ACE. TDGs stimulated endothelial NO production in coronary endothelial cells (CEC) by 52% compared to control. The effects of TDGs were comparable to those of BK and Captopril, both used as positive controls of NO production. Consistent with these effects, TDGs induced, in a dose-dependent manner, endothelial NO-dependent vasodilation in isolated rat aortic rings. These results suggest that TDGs induce endothelial NO production and consequent vasodilation through their ACEi activity. Amaranth TDGs have a high potential as a nutraceutical food in prevention of cardiovascular diseases. Further molecular, cellular and physiological studies are currently under way and the results may contribute to a better understanding and control of cardiovascular disorders.

In vitro penetration of swine oocytes by homologous spermatozoa: Distinct systems for gamete's co-incubation and oocyte's cryopreservation.

In vitro penetration (IVP) of swine oocytes by homologous spermatozoa was evaluated in two experiments using four boars as semen donors. In experiment 1, the IVP rate and the number of penetrating spermatozoa (PSP) were compared using three co-incubation systems for vitrified oocytes and fresh sperm: (1) 35mL petri dishes in a CO(2) incubator, (2) 35mL petri dishes in bags (submarine system) and (3) glass flasks partially submerged in water bath with the same gas mixture used for the bag system. Mean PSP was 8.2+/-10.1 and the IVP rate was 90.5%. The PSP differed across all systems (P=0.0006): 15.5+/-0.5 for flasks, 6.3+/-0.4 for CO(2), and 3.9+/-0.4 for bags. The IVP rate for flasks (95.0%) was greater (P=0.01) than for CO(2) and bags (90.8% and 85.0%, respectively), but it did not differ between flasks and CO(2) for three boars (P>0.05). In experiment 2, co-incubation was done as described for glass flasks in experiment 1. The IVP rate and PSP were compared for cryopreserved oocytes: either vitrified in open pulled straws (OPS), or frozen in cryotubes. Mean PSP was 5.4+/-6.5 and IVP rate was 89.6%. Both PSP and IVP rate were greater (P<0.0001) for oocytes frozen in cryotubes (7.0+/-0.3% and 95.8%, respectively) than those frozen in OPS (3.7+/-0.3% and 83.4%, respectively), with no differences found for three boars (P>0.05). In summary, successful IVP of swine oocytes by homologous spermatozoa can be achieved using gametes incubated in glass flasks and oocytes frozen in cryotubes.

Globulin 11S and its mixture with L-dipalmitoylphosphatidylcholine at the air/liquid interface.

Langmuir films of globulin 11S protein, l-dipalmitoylphosphatidylcholine (L-DPPC), and mixtures of both on water and on buffer subphases were studied. Brewster angle microscopy (BAM) was used to characterize in situ the films morphology along Pi-A isotherms at the air/liquid interface. The L-DPPC monolayer on water behaved as has been reported extensively in the literature but a slight increase on surface pressure and a notable change in domain morphology is observed on buffer. This difference in domain behavior is due to the stabilization interaction of the LE phase by the buffer ions. On the other hand, the protein monolayer was prepared by direct deposit or injection below the surface. Both methods formed mostly a condensed film, with a multilayer formed by globular aggregates in the first method with the two subphases. However, the second method showed different behavior of the protein films depending on the subphase; on water the protein formed a homogeneous film with some globule aggregates, but on buffer a remarkably well-organized monolayer was observed by atomic force microscopy (AFM). Mixtures of globulin 11S and L-DPPC were prepared using both methods for the protein film formation at the air/fluid interface. BAM showed that the mixtures formed coexistence regions between two condensed phases, whose domains of both phases behave like liquids. Fingering phenomena were observed at the interface between protein-rich and L-DPPC-rich domains, which indicates that both phases are fluid. AFM images of the mixtures show the formation of protein- or L-DPPC-rich domains. The liquidlike behavior could be explained due to different sizes of the protein and the L-DPPC, the minority compound in each kind of domain produces defects making them behave as liquids. Interestingly enough, as the monolayer is compressed to higher surface pressure, the lipid molecules are squeezed out and complete separation of the protein and L-DPPC is produced. Furthermore, we present evidence that the protein/L-DPPC mixtures produce films with holes, which might indicate its tendency to form hollow aggregates that could have some relevance in water-channel formation for in vivo seed germination.

Identification of yeast and bacteria involved in the mezcal fermentation of Agave salmiana.

AIMS: To identify the yeast and bacteria present in the mezcal fermentation from Agave salmiana. METHODS AND RESULTS: The restriction and sequence analysis of the amplified region, between 18S and 28S rDNA and 16S rDNA genes, were used for the identification of yeast and bacteria, respectively. Eleven different micro-organisms were identified in the mezcal fermentation. Three of them were the following yeast: Clavispora lusitaniae, Pichia fermentans and Kluyveromyces marxianus. The bacteria found were Zymomonas mobilis subsp. mobilis and Zymomonas mobilis subsp. pomaceae, Weissella cibaria, Weissella paramesenteroides, Lactobacillus pontis, Lactobacillus kefiri, Lactobacillus plantarum and Lactobacillus farraginis. CONCLUSIONS: The phylogenetic analysis of 16S rDNA and ITS sequences showed that microbial diversity present in mezcal is dominated by bacteria, mainly lactic acid bacteria species and Zymomonas mobilis. Pichia fermentans and K. marxianus could be micro-organisms with high potential for the production of some volatile compounds in mezcal. SIGNIFICANCE AND IMPACT OF THE STUDY: We identified the community of bacteria and yeast present in mezcal fermentation from Agave salmiana.

Bioactive peptides in amaranth (Amaranthus hypochondriacus) seed.

Amaranth seeds are rich in protein with a high nutritional value, but little is known about their bioactive compounds that could benefit health. The objectives of this research were to investigate the presence, characterization, and the anticarcinogenic properties of the peptide lunasin in amaranth seeds. Furthermore, to predict and identify other peptides in amaranth seed with potential biological activities. ELISA showed an average concentration of 11.1 microg lunasin equivalent/g total extracted protein in four genotypes of mature amaranth seeds. Glutelin fraction had the highest lunasin concentration (3.0 microg/g). Lunasin was also identified in albumin, prolamin and globulin amaranth protein fractions and even in popped amaranth seeds. Western blot analysis revealed a band at 18.5 kDa, and MALDI-TOF analysis showed that this peptide matched more than 60% of the soybean lunasin peptide sequence. Glutelin extracts digested with trypsin, showed the induction of apoptosis against HeLa cells. Prediction of other bioactive peptides in amaranth globulins and glutelins were mainly antihypertensive. This is the first study that reports the presence of a lunasin-like peptide and other potentially bioactive peptides in amaranth protein fractions.

Modified penicillin acylase signal peptide allows the periplasmic production of soluble human interferon-gamma but not of soluble human interleukin-2 by the Tat pathway in Escherichia coli.

Production of periplasmic human interferon-gamma (hINF-gamma) and human interleukin-2 (hIL-2) by the Tat translocation pathway in Escherichia coli BL21-SI was evaluated. The expression was obtained using the pEMR vector which contains the Tat-dependent modified penicillin acylase signal peptide (mSPpac) driven by the T7 promoter. The mSPpac-hINF-gamma was processed and the protein was transported to periplasm. Up to 30.1% of hINF-gamma was found in the periplasmic soluble fraction, whereas only 15% of the mSPpac-hIL-2 was processed, but hIL-2 was not found in the periplasmic soluble fraction.

A novel binary expression vector for production of human IL-10 in Escherichia coli and Bifidobacterium longum.

A novel expression vector (pLR) driven by hup promoter and Bifidobacterium beta-galactosidase signal peptide was constructed. The pLR vector was used for the expression of the optimized human IL-10 synthetic gene in Escherichia coli and Bifidobacterium longum. In both microorganisms, rhIL-10 was in a soluble form in total extract cells. The recombinant hIL-10 was partially processed in E. coli, whereas in Bifidobacterium all rhIL-10 was found in the mature form.

Characterization of two new rhabdoviruses isolated from midges (Culicoides SPP) in the Brazilian Amazon: proposed members of a new genus, Bracorhabdovirus.

Itacaiunas and Curionopolis viruses were isolated from Culicoides midges in Parauapebas municipality, Pará state, Brazil, in 1984 and 1985, respectively. Itacaiunas virus infected newborn mice and mosquito cells (C6/36), but did not replicate in some mammalian cell lineages; while Curionopolis virus infected only mice. Neither virus showed a serological relationship with any of the 195 known arboviruses circulating in Brazil, nor against 38 other rhabdoviruses isolated worldwide. Both virus particles are bullet-shaped and similar in morphology to that observed for other members of the family Rhabdoviridae. Partial nucleotide sequencing of the N protein showed that those two viruses constitute a separate clade in the family Rhabdoviridae, which we propose to be a new genus, designated Bracorhabdovirus.

Expression and purification of rotavirus proteins NSP5 and NSP6 in Escherichia coli.

Rotaviruses are one of the worldwide leading causes of gastroenteritis in children under 5 yr old. The rotavirus nonstructural NSP5 is a phosphoprotein implicated in viroplasms formation, whereas NSP6 could have a possible regulatory role of NSP5. It has been reported that N- and C-termini of NSP5 are important for their function. However, no structural information on NSP5 and NSP6 proteins is available. Because a high amount of protein is required for structural analysis, efficient expression systems are required. His-tag fusion at the C-terminus and glutathione-S-transferase (GST)-fusion at the N-terminus were used as expression systems, and conditions for recombinant proteins expression were obtained. His-tag fusion was not efficient to produce NSP5 (2% of total protein), but NSP6 was expressed in higher amounts (11% of total protein). In contrast, GSTNSP5 and GST-NSP6 proteins correspond to 34 and 31% of the total proteins, respectively. GST-fusions seem to have a protective effect against nonstructural rotavirus protein toxicity in Escherichia coli; however, in both systems, NSP5 and NSP6 recombinant proteins were expressed as inclusion bodies. Conditions for solubilization and purification of recombinant proteins were achieved. This is the first report of expression and purification of NSP5 and NSP6 recombinant proteins in suitable amounts for further structural analysis.

Functional and rheological properties of amaranth albumins extracted from two Mexican varieties.

The functional and rheological properties of amaranth albumins isolates extracted from two new Mexican varieties were determined. Functional properties tested were protein solubility, foaming, water and oil absorption capacities, emulsifying activity, and emulsion stability. The maximum solubility values for both amaranth albumins were found above pH 6 and values were compared to the solubility of egg albumins. Albumins from amaranth showed excellent foaming capacity and foaming stability at pH 5, suggesting that this protein could be used as whipping agents as egg albumins, also the water and oil absorption capacities reached their maximum values at acidic pH, suggesting that amaranth albumins could be appropriate in preparation of acidic foods. The rheological test based on farinograms and alveograms showed that wheat flour supplemented with 1% amaranth albumins improves the dough properties due to higher mixing stability and the bread had better crumb characteristics. In addition of the known high nutritional values of amaranth albumins, our results indicate the high potential for use of these proteins as an ingredient in food preparations.

Isolation of yellow fever virus from nulliparous Haemagogus (Haemagogus) janthinomys in eastern Amazonia.

In 1998, an epizootic of yellow fever (YF) killed many howler monkeys (Alouatta spp.) in eastern Amazonia near the city of Altamira. An infection level with YF virus of approximately 3.6% was determined from analysis of 456 females of Haemagogus janthinomys Dyar, the main enzootic YF vector in South America. One month later, a second study of 164 females captured in the same place led to infection levels of 0.8% for parous and 2.9% for nulliparous females. These results lead to the conclusion that vertical transmission, one of the key elements in the epidemiology of YF, occurs in South America as it does in Africa.

West Nile virus infection in the golden hamster (Mesocricetus auratus): a model for West Nile encephalitis.

This report describes a new hamster model for West Nile (WN) virus encephalitis. Following intraperitoneal inoculation of a New York isolate of WN virus, hamsters had moderate viremia of 5 to 6 days in duration, followed by the development of humoral antibodies. Encephalitic symptoms began 6 days after infection; about half the animals died between the seventh and 14th days. The appearance of viral antigen in the brain and neuronal degeneration also began on the sixth day. WN virus was cultured from the brains of convalescent hamsters up to 53 days after initial infection, suggesting that persistent virus infection occurs. Hamsters offer an inexpensive model for studying the pathogenesis and treatment of WN virus encephalitis.