Albino Research Articles

Refraction and Low Vision Rehabilitation in Patients with Oculocutaneous Albinism

Purpose: To evaluate the types of refractive errors and compliance of patients of Oculocutaneous Albinism (OCA) to low vision aids.
 Study Design: Descriptive observational study.
 Place and Duration of Study: Provincial Directorate of Health, Adana City Education and Research Hospital, from 2010 to 2018.
 Material and Methods: Seven hundred and fifteen patients attended the hospital between 2010 and 2018 with the complaint of low vision and 31 patients with OCA were included in this study by convenient sampling. Best corrected distance and near visual acuity (VA) was measured along with the complete ocular examination. Patients were classified according to low vision and refraction degrees. High degree near eyeglasses, Galilean and Keplerian telescopes, magnifiers and special filter glasses were used as low vision aids (LVA).
 Results: Mean age was 16.45 ± 12.72 years. On admission, mean distance VA was 0.12 ± 0.07 [mean log MAR 0.9], near VA was 1.48M ± 0.74M, astigmatism was 4.02 ± 1.45 diopters (D), and spherical equivalents were 1.54 ± 4.96 D. Hypermetropia was seen more frequently than myopia. Twenty-seven (87%) patients were prescribed telescopes for distance. Near visual acuity increased from 1.4M ± 0.7M to 0.9M ± 0.4M after rehabilitation. There was an increase in distance visual acuity in all patients (p < 0.001). Seventeen (63%) patients bought the telescope, and 15 (55%) patients used the device. The most preferred special filter glasses were 450nm (39%) and 540 nm (25%).
 Conclusion: Astigmatism in oculocutaneous albinism was with the rule and the most commonly detected refractive error was hypermetropia. Patients are non-compliant in buying telescopes in which case tablet and computers with special applications for low vision can be better options.

Retinal biomarkers and pharmacological targets for Hermansky-Pudlak syndrome 7

Deletion of dystrobrevin binding protein 1 has been linked to Hermansky-Pudlak syndrome type 7 (HPS-7), a rare disease characterized by oculocutaneous albinism and retinal dysfunction. We studied dysbindin-1 null mutant mice (Dys−/−) to shed light on retinal neurodevelopment defects in HPS-7. We analyzed the expression of a focused set of miRNAs in retina of wild type (WT), Dys+/− and Dys−/− mice. We also investigated the retinal function of these mice through electroretinography (ERG). We found that miR-101-3p, miR-137, miR-186-5p, miR-326, miR-382-5p and miR-876-5p were up-regulated in Dys−/−mice retina. Dys−/− mice showed significant increased b-wave in ERG, compared to WT mice. Bioinformatic analysis highlighted that dysregulated miRNAs target synaptic plasticity and dopaminergic signaling pathways, affecting retinal functions of Dys−/− mice. Overall, the data indicate potential mechanisms in retinal neurodevelopment of Dys−/− mice, which may have translational significance in HSP-7 patients, both in terms of diagnostic/prognostic biomarkers and novel pharmacological targets.

Mapping the TYR gene reveals novel and previously reported variants in Eastern Indian patients highlighting preponderance of the same changes in multiple unrelated ethnicities.

Oculocutaneous albinism (OCA) is a group of congenital autosomal recessive disorders with seven known subtypes (OCA1-OCA7) characterized by loss or absence of pigmentation in the skin, hair, and eyes. OCA1, caused by pathogenic variations in the tyrosinase (TYR) gene, has been documented to be the most prevalent subtype across the world including India. In the present study, we recruited 53 OCA-affected individuals from 45 unrelated families belonging to 20 different marriage groups/ethnicities of 15 different districts of West Bengal. We took a targeted sequencing-based approach to find the causal variations in the TYR gene. We report here identification of two novel potentially pathogenic variations [NM_000372.4:c.614C>T, NP_000363.1:p.(Pro205Leu), and NM_000372.4:c.1036+1=/G>T], one novel synonymous TYR variant [NM_000372.4:c.204=/A>G, NP_000363.1:p.(Gln68=)], two pathogenic variations documented for the first time in Indian OCA cases [NM_000372.4:c.1147G>A, NP_000363.1:p.(Asp383Asn), and NM_000372.4:c.585G>A, NP_000363.1:p.(Trp195*)], along with nine previously reported pathogenic variants in 36 out of 53 (∼68%) patients recruited. We report common haplotype backgrounds for the two most prevalent variations [NM_000372.4:c.124G>A, NM_000372.4:c.832C>T] in cases belonging to different marriage/ethnic groups, suggesting a possible founder effect. To our knowledge, this is the most comprehensive genetic study on OCA1 from India, firmly establishing OCA1 as the commonest form of albinism in this part of the world.

The first record of a wild hypopigmented oriental small-clawed otter (Aonyx cinereus)

Hypopigmentation, whose most common forms include albinism and leucism, results in atypical coloration and occurs throughout the animal kingdom. During camera trapping in Bukit Barisan Selatan National Park, Sumatra, we documented the first record of hypopigmentation in oriental small-clawed otters (Aonyx cinereus). Hypopigmentation is rarely documented in the literature, and this appears to be the second record for any otter species.

In-silico analysis of deleterious missense SNPs of human TYR gene associated with oculocutaneous albinism type 1 (OCA1)

Single Nucleotide Polymorphisms (SNPs) are among the major genetic anomalies behind genetically rare disorders. The human TYR gene encodes a key regulatory enzyme, tyrosinase for melanin biosynthesis. Missense mutations in the TYR gene may disrupt the normal function of tyrosinase and cause oculocutaneous Albinism type 1 (OCA1). The present study involves the use of multiple computational tools based on different algorithms for the identification of potential deleterious missense SNPs from the TYR gene. In this study, we identified ten deleterious missense mutations which may be contributing factors for OCA1. The 3D modeling analysis of mutant models of tyrosinase also strengthen the hypothesis that these mutations may induce significant structural and conformational changes on the native tyrosinase enzyme.

Histopathologic patterns of cutaneous malignancies in individuals with oculocutaneous albinism in Anambra state, Nigeria: a paradigm swing?

BackgroundA high proportion of skin cancers in Nigeria occur in Individuals with oculocutaneous albinism (OCA). A reduction or absence of melanin, a skin pigment with photoprotective properties, makes them susceptible to skin malignancies such as squamous cell carcinomas (SCCs), basal cell carcinomas (BCCs) and rarely melanomas. Globally, BCCs are the commonest cutaneous malignancies among Caucasians and in fair-skinned Africans. This has been attributed to the greater effect of melanin in protecting against UV damage in the basal layer of the epidermis. Older retrospective studies on African albinos suggested that SCCs accounted for a higher prevalence of skin cancers in albinos, followed by BCCs. Melanoma has been consistently documented to be rare in all of these reports. Recent reports however noted BCCs to occur at an increasing frequency, suggesting a higher frequency than previously documented. These conflicting reports reflect the need to re-explore the pattern of cutaneous malignancies in albinos in order to reconcile the role of pigmentation, UV exposure and the variance between the frequencies of the different keratinocyte skin cancers among extreme skin phenotypes. This study explores the pattern of cutaneous malignancies seen in albinos in South East Nigeria.ObjectiveTo determine the pattern of cutaneous malignancies among albinos in Anambra state, Nigeria.Materials and methodsA cross-sectional study conducted in Anambra State, Nigeria. Ninety albinos from the Albino foundation Anambra state were recruited. Malignant dermatoses were characterized clinically and confirmed by histology. Fifty-eight lesions from 30 albinos were biopsied to determine the presence of malignancy.ResultsSkin cancers were seen in 20.98% of all participants and in 18 (60%) of all the albinos who had skin biopsy. The SCC/BCC ratio was 1.0: 2.3. There was no cutaneous melanoma.ConclusionContrary to previous reports, it would appear that the pattern of cutaneous malignancies in albinos shows the same trend as that seen in Caucasians and fair-skinned Africans.

A genome-wide scan study identifies a single nucleotide substitution in the tyrosinase gene associated with white coat colour in a red deer (Cervus elaphus) population

BackgroundRed deer with very pale coat colour are observed sporadically. In the red deer (Cervus elaphus) population of Reinhardswald in Germany, about 5% of animals have a white coat colour that is not associated with albinism. In order to facilitate the conservation of the animals, it should be determined whether and to what extent brown animals carry the white gene. For this purpose, samples of one white hind and her brown calf were available for whole genome sequencing to identify the single nucleotide polymorphism(s) responsible for the white phenotype. Subsequently, samples from 194 brown and 11 white animals were genotyped.ResultsBased on a list of colour genes of the International Federation of Pigment Cell Societies, a non-synonymous mutation with exchange of a glycine residue at position 291 of the tyrosinase protein by arginine was identified as the cause of dilution of the coat colour. A gene test led to exactly matching genotypes in all examined animals. The study showed that 14% of the brown animals carry the white gene. This provides a simple and reliable way of conservation for the white animals. However, results could not be transferred to another, unrelated red deer population with white animals. Although no brown animals with a white tyrosinase genotype were detected, the cause for the white colouring in this population was different.ConclusionsA gene test for the conservation of white red deer is available for the population of the Reinhardswald. While mutations in the tyrosinase are commonly associated with oculocutaneous albinism type 1, the amino acid exchange at position 291 was found to be associated with coat colour dilution in Cervus elaphus.

The Epidemiology of Skin Cancer and Public Health Strategies for Its Prevention in Southern Africa.

Skin cancer is a non-communicable disease that has been underexplored in Africa, including Southern Africa. Exposure to solar ultraviolet radiation (UVR) is an important, potentially modifiable risk factor for skin cancer. The countries which comprise Southern Africa are Botswana, Lesotho, Namibia, South Africa, and Swaziland. They differ in population size and composition and experience different levels of solar UVR. Here, the epidemiology and prevalence of skin cancer in Southern African countries are outlined. Information is provided on skin cancer prevention campaigns in these countries, and evidence sought to support recommendations for skin cancer prevention, especially for people with fair skin, or oculocutaneous albinism or HIV-AIDS who are at the greatest risk. Consideration is given to the possible impacts of climate change on skin cancer in Southern Africa and the need for adaptation and human behavioural change is emphasized.

Human Tyrosinase: Temperature-Dependent Kinetics of Oxidase Activity.

Human tyrosinase (Tyr) is involved in pigment biosynthesis, where mutations in its corresponding gene TYR have been linked to oculocutaneous albinism 1, an autosomal recessive disorder. Although the enzymatic capabilities of Tyr have been well-characterized, the thermodynamic driving forces underlying melanogenesis remain unknown. Here, we analyze protein binding using the diphenol oxidase behavior of Tyr and van ’t Hoff temperature-dependent analysis. Recombinant Tyr was expressed and purified using a combination of affinity and size-exclusion chromatography. Michaelis-Menten constants were measured spectrophotometrically from diphenol oxidase reactions of Tyr, using L-3,4-dihydroxyphenylalanine (L-DOPA) as a substrate, at temperatures: 25, 31, 37, and 43 °C. Under the same conditions, the Tyr structure and the L-DOPA binding activity were simulated using 3 ns molecular dynamics and docking. The thermal Michaelis-Menten kinetics data were subjected to the van ‘t Hoff analysis and fitted with the computational model. The temperature-dependent analysis suggests that the association of L-DOPA with Tyr is a spontaneous enthalpy-driven reaction, which becomes unfavorable at the final step of dopachrome formation.

Comprehensive Geno- and Phenotyping in a Complex Pedigree Including Four Different Inherited Retinal Dystrophies.

Inherited retinal dystrophies (IRDs) are characterized by high clinical and genetic heterogeneity. A precise characterization is desirable for diagnosis and has impact on prognosis, patient counseling, and potential therapeutic options. Here, we demonstrate the effectiveness of the combination of in-depth retinal phenotyping and molecular genetic testing in complex pedigrees with different IRDs. Four affected Caucasians and two unaffected relatives were characterized including multimodal retinal imaging, functional testing, and targeted next-generation sequencing. A considerable intrafamilial phenotypic and genotypic heterogeneity was identified. While the parents of the index family presented with rod-cone dystrophy and ABCA4-related retinopathy, their two sons revealed characteristics in the spectrum of incomplete congenital stationary night blindness and ocular albinism, respectively. Molecular testing revealed previously described variants in RHO, ABCA4, and MITF as well as a novel variant in CACNA1F. Identified variants were verified by intrafamilial co-segregation, bioinformatic annotations, and in silico analysis. The coexistence of four independent IRDs caused by distinct mutations and inheritance modes in one pedigree is demonstrated. These findings highlight the complexity of IRDs and underscore the need for the combination of extensive molecular genetic testing and clinical characterization. In addition, a novel variant in the CACNA1F gene is reported associated with incomplete congenital stationary night blindness.

Research Techniques Made Simple: Cell Biology Methods for the Analysis of Pigmentation

Pigmentation of the skin and hair represents the result of melanin biosynthesis within melanosomes of epidermal melanocytes, followed by the transfer of mature melanin granules to adjacent keratinocytes within the basal layer of the epidermis. Natural variation in these processes produces the diversity of skin and hair color among human populations, and defects in these processes lead to diseases such as oculocutaneous albinism. While genetic regulators of pigmentation have been well studied in human and animal models, we are still learning much about the cell biological features that regulate melanogenesis, melanosome maturation, and melanosome motility in melanocytes, and have barely scratched the surface in our understanding of melanin transfer from melanocytes to keratinocytes. Herein, we describe cultured cell model systems and common assays that have been used by investigators to dissect these features and that will hopefully lead to additional advances in the future.

Agave angustifolia albino plantlets lose stomatal physiology function by changing the development of the stomatal complex due to a molecular disruption.

Stomatal development is regulated by signaling pathways that function in multiple cellular programs, including cell fate and cell division. However, recent studies suggest that molecular signals are affected by CO2 concentration, light intensity, and water pressure deficit, thereby modifying distribution patterns and stomatic density and likely other foliar features as well. Here, we show that in addition to lacking chloroplasts, the albino somaclonal variants of Agave angustifolia Haw present an irregular epidermal development and morphological abnormalities of the stomatal complex, affecting the link between the stomatal conductance, transpiration and photosynthesis, as well as the development of the stoma in the upper part of the leaves. In addition, we show that changes in the transcriptional levels of SPEECHLESS (SPCH), TOO MANY MOUTHS (TMM), MITOGEN-ACTIVATED PROTEIN KINASE 4 and 6 (MAPK4 and MAPK6) and FOUR LIPS (FLP), all from the meristematic tissue and leaf, differentially modulate the stomatal function between the green, variegated and albino in vitro plantlets of A. angustifolia. Likewise, we highlight the conservation of microRNAs miR166 and miR824 as part of the regulation of AGAMOUS-LIKE16 (AGL16), recently associated with the control of cell divisions that regulate the development of the stomatal complex. We propose that molecular alterations happening in albino cells formed from the meristematic base can lead to different anomalies during the transition and specification of the stomatal cell state in leaf development of albino plantlets. We conclude that the molecular alterations in the meristematic cells in albino plants might be the main variable associated with stoma distribution in this phenotype.

Protein Stability and Functional Characterization of Intra-Melanosomal Domain of Human Recombinant Tyrosinase-Related Protein 1.

Pigmentation is the result of a complex process by which the biopolymer melanin is synthesized and packed into melanosomes of melanocytes. Various types of oculocutaneous albinism (OCA), a series of autosomal recessive disorders, are associated with reduced pigmentation in the skin, eyes, and hair due to genetic mutations of proteins involved in melanogenesis. Human tyrosinase (Tyr) and tyrosinase-related protein 1 (Tyrp1) drives the enzymatic process of pigment bio-polymerization. However, within the melanogenic pathway, Tyrp1 has catalytic functions not clearly defined and distinct from Tyr. Here, we characterize the biochemical and biophysical properties of recombinant human Tyrp1. For this purpose, we purified and analyzed the intra-melanosomal domain (Tyrp1tr) for protein stability and enzymatic function in conditions mimicking the environment within melanosomes and the endoplasmic reticulum. The study suggests that Tyrp1tr is a monomeric molecule at ambient temperatures and below (<25 °C). At higher temperatures, >31 °C, higher protein aggregates form with a concurrent decrease of monomers in solution. Also, Tyrp1tr diphenol oxidase activity at pH 5.5 rises as both the pre-incubation temperature and the higher molecular weight protein aggregates formation increases. The enhanced protein activity is consistent with the volume exclusion change caused by protein aggregates.

Visual rehabilitation of people with oculocutaneous albinism in a tertiary clinical setting in Pakistan

PURPOSE:All people with oculocutaneous albinism (OCA) have reduced vision. This study aimed to assess the benefits of low vision aids for people with OCA.METHODS:Seventy-seven consecutive people with OCA age 4 years and above examined in a low vision clinic were included in the study. Uncorrected and best-corrected visual acuity (VA), VA with low vision devices, types of low vision aids, and refractive errors data were analyzed.RESULTS:Of the 77 people with OCA, 57% were in the age group between 4 and 15 years and 43% in the age group of 16 years and above. At the time of presentation, the percentages of visually impaired, severe visually impaired, and blind (using WHO low vision criteria) were 52%, 22%, and 25%. Among them, 39% has near VA of 1 M or better. Difference in the means of the spherical equivalent refractive error in the right eyes and left eyes was −0.494 diopters (−01.686, 0.699; 95% confidence interval). VA improved significantly after adequate refractive correction by more than one log MAR lines in 38.6% (P < 0.01). With low vision devices, in 85.7% (n = 66) participants, VA was enhanced to normal level (6/18 or better) in the better eye while 7.8% still remained in the blind category. Telescopes were prescribed to 61% people for the enhancement of distance VA and hand hold magnifiers were prescribed to 22% people to meet their needs.CONCLUSION:Low vision aids can be successfully used in visual rehabilitation of people with OCA to meet their needs.

Amelanotic melanoma in a patient with oculocutaneous albinism

Oculocutaneous albinism is a genetically heterogeneous, autosomal recessive group of disorders characterized by a generalized decreased or absence of melanin pigment in the eyes, hair, and skin. These patients have a greater sensitivity to UV radiation and a predisposition to skin tumors, mainly squamous cell carcinoma and basal cell carcinomas, and to a lesser extent malignant melanomas. Melanoma can be one of the most challenging cancers to diagnose in patients with albinism. We report an uncommon clinical presentation of melanoma, an amelanotic melanoma in the right supraciliar region in a patient with oculocutaneous albinism. The clinical presentation was an erythematous, scaly and ill-defined plaque. The skin biopsy revealed a lentigo maligna melanoma. Amelanotic melanomas are one of the two most difficult to diagnose subtypes of melanoma, together with the nevoid type. Melanoma in oculocutaneous albinism patients are often amelanotic, which makes their clinical diagnosis very difficult. These patients should be examined in the dermatology department at least once a year and it is recommended to have a high index of suspicion.

Nonhuman Primate Model of Oculocutaneous Albinism with TYR and OCA2 Mutations.

Human visual acuity is anatomically determined by the retinal fovea. The ontogenetic development of the fovea can be seriously hindered by oculocutaneous albinism (OCA), which is characterized by a disorder of melanin synthesis. Although people of all ethnic backgrounds can be affected, no efficient treatments for OCA have been developed thus far, due partly to the lack of effective animal models. Rhesus macaques are genetically homologous to humans and, most importantly, exhibit structures of the macula and fovea that are similar to those of humans; thus, rhesus macaques present special advantages in the modeling and study of human macular and foveal diseases. In this study, we identified rhesus macaque models with clinical characteristics consistent with those of OCA patients according to observations of ocular behavior, fundus examination, and optical coherence tomography. Genomic sequencing revealed a biallelic p.L312I mutation in TYR and a homozygous p.S788L mutation in OCA2, both of which were further confirmed to affect melanin biosynthesis via in vitro assays. These rhesus macaque models of OCA will be useful animal resources for studying foveal development and for preclinical trials of new therapies for OCA.

Protective effect of lycopene against tamoxifen-induced hepatotoxicity in albino rats

Background: Tamoxifen citrate (TAM) is a drug of choice for the treatment of hormone-dependent breast cancer, but its use has been associated with frequent hepatotoxicity. Aim: This study evaluated the protective effect of lycopene (LYP) against hepatotoxicity induced by TAM in albino rats. Methods: Adult female albino rats (200–250 g) were divided into eight groups of n = 5. Group 1 (control) received normal saline (0.2mL) intraperitoneally (i.p.), daily for 7 days. Groups 2–4 were treated daily with LYP (10 mg/kg, 20 mg/kg, and 40 mg/kg) (i.p.) for 7 days, respectively. Group 5 was treated daily with TAM (45 mg/kg) i.p. for 7 days. Groups 6–8 were supplemented daily with LYP (10 mg/kg, 20 mg/kg, and 40 mg/kg) before treatment with TAM (45 mg/kg) i.p. for 7 days, respectively. At the end of treatment, the rats were anesthetized and blood samples were collected and assessed for serum markers of liver function. Liver samples were harvested for histology and biochemical assessments. Results: Significant (P

Selenium as a therapeutic adjuvant for isoniazid/rifampicin-induced hepatotoxicity

BACKGROUND: Isoniazid-rifampicin (INH-RIF) is used for the treatment of tuberculosis, but its hepatotoxicity is a serious health predicament. Selenium (Se) is a trace element with potential to safeguard cells from damage. AIM AND OBJECTIVE: This study assessed the potential of Se to prevent INH/RIF-induced hepatotoxicity in albino rats. MATERIALS AND METHODS: Forty-five adult male albino rats were randomly assigned to four groups. Group 1A (Placebo control) and Group 1B (Solvent control) were orally treated with normal saline (0.2mL) and corn oil (0.2mL) daily for 21 days, respectively. Group 2 (2A–2C) was orally treated with Se (0.1, 0.2, and 0.4 mg/kg) daily for 21 days. Group 3 was orally treated with INH-RIF (50/100 mg/kg) daily for 21 days. Group 4 (4A–4C) was orally pretreated with Se (0.1, 0.2, and 0.4 mg/kg) before oral treatment with INH-RIF (50/100 mg/kg) daily for 21 days, respectively. After treatment, the rats were weighed and anesthetized. Blood samples were collected and analyzed for serum liver function markers. Liver samples were weighed and analyzed for histology and biochemical indices. RESULTS: INH-RIF caused significant (P CONCLUSION: Se may serve as an adjuvant treatment for hepatotoxicity caused by INH-RIF.

Molecular changes in Trypanosoma evansi after treatment against trypanosomosis.

Neither physiological nor pathological changes following treatments explained why trypanosomes in the same group of experimentally treated animals correlated in virulence. Also, they behaved like each other but not similar to other groups despite the same T. evansi injected strain. The current study aims to discuss whether molecular changes might occur to Trypanosoma evansi isolates followed treatments are responsible for that difference or not. Ten preserved isolates from T. evansi after previous treatments besides the original strain of T. evansi that injected before treatments were used in the present study. These isolates were intraperitoneally inoculated in 11 groups of male Wister Albino rats with equal doses. Parasitological findings and the molecular changes accompanied were discussed along with the experiment based on PCR-TR3/TR4 specific-primers. The study also achieved alignments, gene sequence and phylogenetic analysis for submitted and reference strains belong to T. evansi, T. brucei, T. b. brucei, and T. b. gambiense deposited in GenBank. The present results assessed molecularly the effectiveness and highly antitrypanosomal activity of human plasmas O+ and A+ on T. evansi than others, and how their strains drifted from its original sequence to the nearest form of T. brucei. At the same time, T. evansi in other plant extract groups multiplied progressively like cancer cells and became more virulent and close to reference strains of T. evansi. Our data further indicated that T. evansi after treatment was a paraphyletic group. It also corroborated the antitrypanosomal activityspecificity and the molecular changes occurring were correlated to the type of treatment.

Evidences of brain and lung invasion of a local water Cryptosporidium parvum isolate in comparison to Iowa strain: serological and immunohistochemical cytokine evaluation.

Cryptosporidium spp. is an obligate intracellular parasite that has become a community threat. The pathological consequences of cryptosporidiosis vary not only in different Cryptosporidium species but even among different isolates of the same species. The present study aimed to track the serological and immunohistopathological differences between animals infected by Cryptosporidium parvum "Iowa isolate" (CPI) and Cryptosporidium parvum "water isolate" isolated from a local water supply in Assiut Governorate, Egypt (CPW). Three experimental groups were encountered: negative control group (C), the CPI group and the CPW group; each contains ten Swiss albino mice. Serum cytokine: IL10 and TNF-α were measured. Expression of Cryptosporidium antigen and CD3 in the intestinal, pulmonary and brain tissue were evaluated through immunohistochemical assay. IL10 and TNF-α were elevated in both infected groups, over expression of Cryptosporidium protein and CD3 in the intestinal, pulmonary and brain tissue in CPW infected group compared to Iowa infected one. Multi-organs affection occurred in the CPW indicating more severe pathogenicity and virulence than standard Iowa isolate. The local C. parvum isolate was more virulent than tested Iowa isolate as it spread extra-intestinally to reach brain tissue.