Ovine Strains Research Articles

Prevalence of ovine and bovine respiratory syncytial virus infections in cattle determined with a synthetic peptide-based immunoassay.

Subgroup-specific peptide-based enzyme-linked immunosorbent assays from the G-protein of the ovine and bovine respiratory syncytial virus (RSV), respectively, were used to determine the prevalence of the ovine and bovine subgroup strains of RSV infections in cattle. A total of 1,102 bovine serum samples were obtained from 6 diagnostic laboratories located in the northwestern and the southeastern USA and were tested for antibody to either the bovine or ovine subgroups of RSV. Antibody to viruses from each subgroup was present in samples from each region and all states tested. The Southeast had a higher prevalence of the bovine subgroup strains (69.5%). Then did the Northwest (40.9%). The prevalence of the ovine strain was similar for the two regions (16.7% in the southeast, 14.9% in the northwest). The overall prevalence was 56.6% for the bovine strain and 15.9% for the ovine strain. These results suggest members of the ovine subgroup of RSV circulate in the cattle population but with less frequency than those viruses of the bovine subgroup.

Persistence of Ehrlichia phagocytophila Infection in Two Age Groups of Lambs

Tick-borne fever (TBF) is caused by the rickettsiae Ehrlichia phagocytophila and is a common disease in sheep in tick (Ixodes ricinus) infested areas in Norway. Earlier investigations have shown that some sheep could remain infected for several months after the primary infection. In this study, the persistence of E. phagocytophila after experimental infection was investigated in 2 age groups of lambs. Six lambs (1–2 weeks old) and 14 lambs (6–8 months old) were inoculated intravenously with an ovine strain of E. phagocytophila and thereafter examined clinically (including daily body temperature recording) and by haematological and serological (E. equi antibodies) methods for the next 4 months. At the end of this period, the lambs were examined for a TBF infection by blood smear investigation and blood inoculation studies. The infection was demonstrated in 19 (95%) of the 20 lambs.

Ovine scrapie: priorities and importance.

Ovine and caprine scrapie occupies a unique place among animal transmissive spongiform encephalopathies (TSE). It is an object of intensive biomedicinal, ecological and economical studies. Its causative agents are demonstrably associated with the development of TSE in farmed minks, goats and moufflons. Ovine strains of scrapie occurring in North America (particularly in the USA) differ from strains which occur in Europe and were present at the onset of development of TSE in three species of deer living in free nature and in captivity in the USA. The studies dealing with the development of bovine spongiform encephalopathy (BSE) of the English type have indicated justifiably that its origin is associated with one (or more) heretofore unidentified ovine strain. The development of a variant form, the Creutzfeldt-Jacob disease in humans, and transmission of the BSE agent to several families of bovidae, felidae and primates, puts stress on its zoonotic potential. All this leads to the conclusion that domesticated sheep are the decisive reservoir species of animal TSE. They have been infected to an unknown extent with the causative agent of BSE probably through contaminated meat-bone meal. The occurrence of natural ovine prion isolates with properties similar to those of the BSE agent requires that scrapie should be included in the surveillance of human and animal TSE. At present, scrapie is a noticeable disease also in other than European Communities Member States. It is on the list B of the International Epizootics Office. Many countries have initiated control of ovine scrapie. It should therefore become a topical question also in Central and Eastern European countries. Elimination or even eradication of ovine scrapie (or its causative agents) from populations of small and large domestic ruminants is the prerequisite for prevention of penetration of ovine pathogenic prions into the human feed chain. Moreover, it should be ensured that these species will be able to produce foods of a new type (immunotrition and similar) or proteins with therapeutic effects in the near future. Our study established that the PrP genotype of Valachian rams, the Slovak autochthonous breed, contains also VRQ and ARQ alleles encoding the susceptibility to scrapie. Their selection is part of the improvement of Slovak Valachian sheep towards resistance to scrapie.

Epidemiology of ovine Campylobacter infection determined by numerical analysis of electrophoretic protein profiles.

The relationship of 50 Campylobacter strains isolated from aborted ovine foetuses, and the faeces of sheep, cattle and chickens were determined by numerical analysis of electrophoretic (SDS-PAGE) protein profiles. Comparison of protein patterns by numerical methods revealed differences between C. fetus ssp. fetus, C. jejuni, and C. coli strains as well as heterogeneity among isolates from different outbreaks. Isolates from each farm produced a distinct cluster and flocks from different locations were found to be infected with relatively different strains. In most cases, protein patterns of ovine foetal isolates were very similar to those of ovine faecal isolates. Ovine isolates of C. fetus ssp. fetus, C. jejuni and C. coli gave similar protein patterns to the corresponding Campylobacter species isolated from cattle or chicken, on the same farm. Thus, it was concluded that certain protein types of ovine Campylobacter strains were more likely associated with local areas, and Campylobacter strains causing ovine abortions are distributed in the environment more widely than assumed to date.

Evaluation of strain-specific primer sequences from an abortifacient strain of ovine Chlamydophila abortus ( Chlamydia psittaci) for the detection of EAE by PCR

Strain-specific primer sequences derived from the helicase gene of an ovine abortifacient strain (S26/3) of Chlamydophila abortus ( Chlamydia psittaci) were evaluated for the diagnosis of enzootic abortion in ewes (EAE) by polymerase chain reaction (PCR). C. abortus DNA was amplified from tissues submitted from ovine abortion cases using genus-specific and strain-specific primers in a standard thermal cycler. Amplification was followed by Southern blotting and hybridisation with a strain-specific probe. Real-time PCR was also evaluated using strain-specific primers in a microvolume fluorimeter-based thermal cycler (LightCycler™). Detection using both PCR methods was compared with other diagnostic methods against the standard of McCoy cell culture isolation. In this paper we report the application of strain-specific PCR as a fast, sensitive, specific method for the detection of EAE.

The Cys(3)-His(1) motif of the respiratory syncytial virus M2-1 protein is essential for protein function.

The M2 gene of respiratory syncytial (RS) virus has two open reading frames (ORFs). ORF1 encodes a 22-kDa protein termed M2-1. The M2-1 protein contains a Cys(3)-His(1) motif (C-X(7)-C-X(5)-C-X(3)-H) near the amino terminus. This motif is conserved in all human, bovine, and ovine strains of RS virus. A similar motif found in the mammalian transcription factor Nup475 has been shown to bind zinc. The M2-1 protein of human RS virus functions as a transcription factor which increases polymerase processivity, and it enhances readthrough of intergenic junctions during RS virus transcription, thereby acting as a transcription antiterminator. The M2-1 protein also interacts with the nucleocapsid protein. We examined the effects of mutations of cysteine and histidine residues predicted to coordinate zinc in the Cys(3)-His(1) motif on transcription antitermination and N protein binding. We found that mutating the predicted zinc-coordinating residues, the cysteine residues at amino acid positions 7 and 15 and the histidine residue at position 25, prevented M2-1 from enhancing transcriptional readthrough. In contrast, mutations of amino acids within this motif not predicted to coordinate zinc had no effect. Mutations of the predicted zinc-coordinating residues in the Cys(3)-His(1) motif also prevented M2-1 from interacting with the nucleocapsid protein. One mutation of a noncoordinating residue in the motif which did not affect readthrough during transcription, E10G, prevented interaction with the nucleocapsid protein. This suggests that M2-1 does not require interaction with the nucleocapsid protein in order to function during transcription. Analysis of the M2-1 protein in reducing sodium dodecyl sulfate-polyacrylamide gels revealed two major forms distinguished by their mobilities. The slower migrating form was shown to be phosphorylated, whereas the faster migrating form was not. Mutations in the Cys(3)-His(1) motif caused a change in distribution of the M2-1 protein from the slower to the faster migrating form. The data presented here show that the Cys(3)-His(1) motif of M2-1 is essential for maintaining the functional integrity of the protein.

Epidemiological Study of pap Genes among Diarrheagenic or Septicemic Escherichia coli Strains Producing CS31A and F17 Adhesins and Characterization of Pap 31A Fimbriae

The association of the pap operon with the CS31A and F17 adhesins was studied with 255 Escherichia coli strains isolated from calves, lambs, or humans with diarrhea. The three classes of PapG adhesin with different receptor binding preferences were also screened. The pap operon was associated with 50 and 36% of human strains that produced CS31A and ovine strains that produced F17, respectively. Among the bovine isolates, the pap operon was detected in 61% of the CS31A-positive isolates and 72% of the strains that produce both CS31A and F17. The class II adhesin gene was present in bovine (20%) and ovine (71%) isolates. Both class II and III adhesins were genetically associated with 36% of the human strains. The highest prevalence of the pap operon was observed among E. coli strains that produce additional adhesins involved in the binding of bacteria to intestinal cells. Among the bovine isolates, the reference strain for CS31A and F17c was found to be positive for the pap operon. Phenotypic and genotypic characterizations were undertaken. Pap(31A) appeared as fine and flexible fimbriae surrounding the bacteria but did not mediate adhesion to calf intestinal villi. Pap(31A) production was optimal with bacteria cultured on minimal growth media and repressed by addition of exogenous leucine. The deduced amino acid sequence of the PapA(31A) structural subunit showed 57 to 97% identity with the different P-related structural subunits produced by E. coli strains isolated from pigs with septicemia or humans with urinary tract infections. None of the three papG allelic variants was detected, but a homologous papG gene was present in the chromosome of strain 31A.

Casein kinase 2-mediated phosphorylation of respiratory syncytial virus phosphoprotein P is essential for the transcription elongation activity of the viral polymerase; phosphorylation by casein kinase 1 occurs mainly at Ser(215) and is without effect.

The major site of in vitro phosphorylation by casein kinase 2 (CK2) was the conserved Ser(232) in the P proteins of human, bovine, and ovine strains of respiratory syncytial virus (RSV). Enzymatic removal of this phosphate group from the P protein instantly halted transcription elongation in vitro. Transcription reconstituted in the absence of P protein or in the presence of phosphate-free P protein produced abortive initiation products but no full-length transcripts. A recombinant P protein in which Ser(232) was mutated to Asp exhibited about half of the transcriptional activity of the wild-type phosphorylated protein, suggesting that the negative charge of the phosphate groups is an important contributor to P protein function. Use of a temperature-sensitive CK2 mutant yeast revealed that in yeast, phosphorylation of recombinant P by non-CK2 kinase(s) occurs mainly at Ser(215). In vitro, P protein could be phosphorylated by purified CK1 at Ser(215) but this phosphorylation did not result in transcriptionally active P protein. A triple mutant P protein in which Ser(215), Ser(232), and Ser(237) were all mutated to Ala was completely defective in phosphorylation in vitro as well as ex vivo. The xanthate compound D609 inhibited CK2 but not CK1 in vitro and had a very modest effect on P protein phosphorylation and RSV yield ex vivo. Together, these results suggest a role for CK2-mediated phosphorylation of the P protein in the promoter clearance and elongation properties of the viral RNA-dependent RNA polymerase.

Standardisation of restriction fragment length polymorphism analysis for Mycobacterium avium subspecies paratuberculosis

DNA from 1008 strains of Mycobacterium avium subspecies paratuberculosis, digested by restriction endonucleases PstI and BstEII, was hybridised with a standard IS900 probe prepared by PCR and labelled non-radioactively by ECL. DNA fingerprints were scanned by CCD camera and analysed using the software Gel Compar (Applied Maths, Kortrijk, Belgium). Thirteen restriction fragment length polymorphism (RFLP) ( PstI) types were detected, which where designated as A, B, C, D, E, F, G, H, I, J, K, L and M in accordance with the study of Pavlik et al. (1995) [Pavlik, I., Bejckova, L., Pavlas, M., Rozsypalova, V., Koskova, S., 1995. Characterization by restriction endonuclease analysis and DNA hybridization using IS900 of bovine, ovine, caprine and human dependent strains of Mycobacterium paratuberculosis isolated in various localities. Vet. Microbiol. 45, 311–318]. Twenty RFLP ( BstEII) types were detected and designated as C1–3, C5, C7–20, S1 and I1 in accordance with the study by Collins et al. 1990 [Collins, D.M., Gabric, D.M., de Lisle, G.W., 1990. Identification of two groups of Mycobacterium paratuberculosis strains by restriction endonuclease analysis and DNA hybridization. J. Clin. Microbiol. 28, 1591–1596]. A combination of both RFLP ( PstI) and RFLP ( BstEII) results revealed a total of 28 different RFLP types. All the RFLP types and detailed protocols are available at Internet web site WWW...: http://www.vri.cz/wwwrflptext.htm.

Transmission of virulent footrot between sheep and goats.

To determine the infectivity of ovine and caprine strains of Dichelobacter nodosus for both sheep and goats. Pen experiments in which 20 sheep and 19 goats were challenged directly with the two strains, and transmission experiments on pasture, using donors infected by experimental challenge. Sheep and goat strains of D nodosus infected both animal species in experimental challenges. Animals so infected transmitted footrot to both sheep and goats on pasture plots. A significantly smaller proportion of goats than sheep was infected when challenged with either strain. The interval between exposure and development of footrot in goats was longer than in sheep when recipient animals were exposed to infected donors on pasture. The disease was less invasive in goats than in sheep. With the strains of D nodosus used there was no evidence of host specificity. Direct transmission of footrot can occur between sheep and goats in the same environment. There is a need to include goats in ovine footrot eradication programs and vice versa.

Characterization of nonenterotoxigenic Escherichia coli strains producing F17 fimbriae isolated from diarrheic lambs and goat kids.

Forty-five ovine and caprine nonenterotoxigenic Escherichia coli strains producing F17-related fimbriae were characterized with respect to the fimbrial structural subunit and adhesin subtypes produced. In addition, several characteristics related to the virulence of strains producing F17 fimbriae were studied. Most of the strains (73%) possessed the f17cA structural subunit gene, whereas the f17aA and f17dA genes were detected only on three (6%) and two (4%) strains, respectively. The f17bA gene was not detected. All but one of these strains possessed the f17G genes of the adhesin subfamily II. The only strain having the f17G gene of subfamily I possessed the structural subunit gene f17dA. Sequencing of the f17A and f17G genes of four selected strains confirmed the association of f17cA and f17dA structural subunit genes with the f17G genes of the adhesin subfamily II. These results indicated that adhesins of the subfamily II are prominent among ovine and caprine isolates and that they are indistinctly associated with the F17 structural subunit subtypes on these field strains. CS31A- and CNF2-related genes were not detected. Most of the strains adhered in vitro to ovine intestinal brush borders (36 of 45) and agglutinated the erythrocytes of different species in the presence of D-mannose (39 of 45). F17-positive strains produced colicin V (57%) and were resistant to the bactericidal effect of serum (91%) in significantly higher percentages than F17-negative strains (34% produced colicin V, and 66% were serum resistant). Thus, most of the studied ovine and caprine strains showed phenotypic characteristics of septicemic strains.

Evaluation of modified BACTEC 12B radiometric medium and solid media for culture of Mycobacterium avium subsp. paratuberculosis from sheep.

Definitive diagnosis of Johne's disease in ruminants depends on confirming the presence of the causative bacterium, Mycobacterium avium subsp. paratuberculosis, in tissues of the host. This is readily achieved in most ruminant species by culture. However, culture of clinical specimens from sheep in many countries has been unrewarding. Such a culture from sheep was achieved recently in Australia by using a radiometric culture medium. The aims of the present study were to evaluate the culture of M. avium subsp. paratuberculosis from sheep by using modified BACTEC 12B radiometric medium, to determine the sensitivity of culture in relation to histopathology, and to evaluate a range of solid media. Culture of M. avium subsp. paratuberculosis from sheep with Johne's disease is a sensitive method of diagnosis: intestinal tissues from all 43 animals with multibacillary disease and all 22 animals with paucibacillary disease were culture positive, while 98% of feces from 53 animals with multibacillary disease and 48% of feces from 31 animals with paucibacillary disease were culture positive. Of sheep without histological evidence of Johne's disease from infected flocks, intestinal tissue from 32% of 41 were culture positive, while feces from 17% of 41 were culture positive. Consequently, culture is recommended as the "gold standard" test for detection of ovine Johne's disease. Of the wide range of solid media that were evaluated, only modified Middlebrook 7H10 and 7H11 agars, which were very similar in composition to modified BACTEC 12B medium, yielded growth of ovine strains of M. avium subsp. paratuberculosis. The sensitivity of detection of M. avium subsp. paratuberculosis on solid media was slightly lower than that in modified BACTEC 12B radiometric medium. Both egg yolk and mycobactin J were essential additives for growth of ovine strains of M. avium subsp. paratuberculosis in both liquid and solid media.

Serotyping of Chlamydial Clinical Isolates from Birds with Monoclonal Antibodies

Forty-nine avian chlamydial strains, isolated mainly from various regions in France and from different species of birds, were analyzed and tested with a panel of nine monoclonal antibodies (MAbs) by the indirect microimmunofluorescence test (MIF). The MAbs included five serovar-specific MAbs, three MAbs raised against Chlamydia psittaci and Chlamydia pecorum ovine strains, and one genus-specific MAb. Of the 49 isolates, 41 came from parrots or budgerigars; the rest were from pigeons, a canary, a duck, and a dove. Two additional strains were from unknown hosts. Most of these avian strains were successfully serotyped according to their reactions with five serovar-specific MAbs by the MIF test. The serovars of 44 strains were determined: 39 were of serovar A, 3 of serovar B, and 2 of serovar E. The remaining five isolates were unclassified because they did not react with any of five serovar-specific MAbs but did react with genus MAb or the MAbs produced with ovine strains. The five unclassified isolates (two from budgerigars, two from Gabon gray parrots, and one from a duck) indicate that one or more additional serovars of C. psittaci exist in birds. The heterogeneity within each subgroup was evident because the 49 avian isolates gave 10 subgroups when the results of the five serovar-specific MAbs were combined with results from the three MAbs produced with ovine strains. This heterogeneity of the serovar isolates, as shown by the combination of MAbs, could provide strain markers very useful for epidemiologic studies.

Genetic analysis of the G and P genes in ungulate respiratory syncytial viruses by RNase A mismatch cleavage method

The G and P genes of bovine, ovine and caprine respiratory syncytial (RS) viruses were analyzed by RNase A one-dimensional fingerprinting, using A51908 as the reference strain. Antisense G or P RNA probes of bovine RS virus strain A 51908 were hybridized to total RNA extracted from bovine turbinate cells infected with bovine, ovine or caprine RS virus strains. The RNA:RNA heteroduplexes were digested with RNase A and the resistant products were analyzed by gel electrophoresis. Comparative analysis of the cleavage patterns revealed heterogeneity among bovine, ovine and caprine RS virus isolates. Ovine RS virus strains generated RNA cleavage patterns more distantly related to the bovine or caprine RS virus strains, particularly in the G gene. Statistical analysis of the results obtained indicated that genetic differences between bovine and ovine viruses were larger, compared with the ones among bovine strains themselves. The same analysis also revealed a close genetic relation among bovine and caprine strains. These results are discussed in terms of ungulate RS virus genetic variation and vaccine development.

Lipopolysaccharide expression within the genus Bordetella: influence of temperature and phase variation.

LPSs play an important role in bacterial pathogenesis. In this study, the LPS expression of the seven known Bordetella species and its dependency on growth temperature was analysed by oxidative silver staining of proteinase-K-treated whole bacteria separated by Tricine-SDS-PAGE. The bordetellae were found to have extensively variable LPS in a species-specific way. In addition, the human and ovine Bordetella parapertussis strains exhibited host-specific LPS expression. LPSs from human B. parapertussis strains grown at 37 and 25 degrees C were distinct. Growth temperature also affected LPS production by several Bordetella bronchiseptica strains. In some of these cases, BvgAS, the global regulator of virulence factors, was involved in this regulation of LPS biosynthesis. In contrast, no evidence was found for the involvement of the Bordetella pertussis BvgAS system in regulation of LPS synthesis. The obligate human pathogens B. pertussis and Bordetella holmesii are closely related but were shown to produce immunologically distinct LPSs. These species are isolated from the upper respiratory tract and blood, respectively. This raises several interesting questions concerning the potential role of LPS as a virulence factor in the infection processes.

Insulin-like growth factor (IGF)-I and -II and IGFBP secretion by ovine satellite cell strains grown alone or in coculture with 3T3-L1 preadipocytes.

The current study was designed to examine the effects of muscle and fat stem cell coculture on the secretion of insulinlike growth factor (IGF)-I and -II and IGF binding proteins (IGFBP) by these cells. Two sheep satellite cell strains with negligible or high potential for differentiation (10A and 0(1), respectively) were placed in coculture with 3T3-L1 preadipocytes using a filter support to separate the two cell types. Media conditioned by the cells grown alone or in coculture were analyzed for IGFs by RIA or IGFBPs by ligand blotting. The numbers of satellite cells and preadipocytes declined throughout the 5-d culture period, although coculture slowed the 3T3-L1 decline but hastened the satellite cell decline. The satellite cell strains and 3T3-L1 cells secreted small amounts of IGF-I (< or = 2 ng/ml) and IGF-II (< 10 ng/ml) over the 5-d culture period. Coculture did not increase the amount of IGF-I and -II in conditioned media. The lowly differentiating 10A cells secreted barely detectable amounts of the low molecular weight IGFBP-3 subunit (34 kDa), IGFBP-2 (28 kDa), and IGFBP-4 (18 kDa). Coculture of 10A and 3T3-L1 cells potentiated secretion of IGFBP-2 and -3. Strain 0(1), which readily differentiates, secreted high levels of both IGFBP-3 subunits (34 and 39 kDa) and IGFBP-2 (28 kDa), as well as significant amounts of the 18 kDa IGFBP-4. Coculture did not alter IGFBP secretion of 0(1) cells. This study showed that while IGF-I and -II levels in media conditioned by sheep satellite cell strains are low and relatively invariant, the intensity and complexity of IGFBP patterns increases with time in culture and with the potential for differentiation of the satellite cell strains. Coculture with preadipocytes appeared to potentiate IGFBP secretion while reducing satellite cell viability.

Phylogenetic analyses of Chlamydia psittaci strains from birds based on 16S rRNA gene sequence.

The nucleotide sequences of 16S ribosomal DNA (rDNA) were determined for 39 strains of Chlamydia psittaci (34 from birds and 5 from mammals) and for 4 Chlamydia pecorum strains. The sequences were compared phylogenetically with the gene sequences of nine Chlamydia strains (covering four species of the genus) retrieved from nucleotide databases. In the neighbor-joining tree, C. psittaci strains were more closely related to each other than to the other Chlamydia species, although a feline pneumonitis strain was distinct (983 to 98.6% similarity to other strains) and appeared to form the deepest subline within the species of C. psittaci (bootstrap value, 99%). The other strains of C. psittaci exhibiting similarity values of more than 99% were branched into several subgroups. Two pigeon strains and one turkey strain formed a distinct clade recovered in 97% of the bootstrapped trees. The other pigeon strains seemed to be distinct from the strains from psittacine birds, with 88% of bootstrap value. In the cluster of psittacine strains, three parakeet strains and an ovine abortion strain exhibited a specific association (level of sequence similarity, 99.9% or more; bootstrap value, 95%). These suggest that at least four groups of strains exist within the species C. psittaci. The 16S rDNA sequence is a valuable phylogenetic marker for the taxonomy of chlamydiae, and its analysis is a reliable tool for identification of the organisms.

Serological survey of chlamydial antibody in post-natal sera

Questionnaires (3426; 72.8%) and blood samples (3890; 82.6%) were analysed from 4704 women post-natally. The answers to the questionnaire confirmed that those patients living in areas with the highest percentage employed in agriculture were most likely to be in direct or indirect contact with sheep or sheep products. When the 788 (20.3%) of the sera with group specific antibody were examined for type-specific antibody, 291 (7.5%) reacted with Chlamydia trachomatis, 153 (3.9%) with Chlamydia pneumoniae, but only one (0.03%) with Chlamydia psittaci. Thus, it would appear that C. psittaci was not an important pathogen in this survey, despite the largest proportion of blood samples being submitted from those most likely to be employed in agriculture. However, in the course of this survey the three patients who had previously suffered chlamydia-associated abortion had successful pregnancies and submitted blood specimens. Serological studies on the serial bloods from these patients showed that, despite developing antibody to the C. psittaci pool and the ovine abortion strain of C. psittaci following abortion, this antibody waned. At the time of the subsequent successful pregnancy, serological results would not have detected a previous C. psittaci infection, but one due to C. pneumoniae. Thus, the results of a survey such as this must be interpreted with caution.

Increase of glycocalyx and altered lectin agglutination profiles of Pasteurella haemolytica A1 after incubation in bovine subcutaneous tissue chambers in vivo or in ruminant serum in vitro.

Pasteurella haemolytica serotype A1 (bovine strain OK) was incubated for 2 and 6 h in bovine subcutaneous tissue chambers in vivo, and ovine strain 82-25 and bovine strain L011 were incubated in vitro for 2 h in heat-inactivated ovine or bovine serum from which gamma globulin had been depleted by protein G affinity chromatography to assess changes in morphology and lectin agglutination profiles (strains 82-25 and L101 only). Cells, removed from chambers after 2 h, were covered with an extensive, dense glycocalyx extending approximately 0.5 microm from the cell surface. In many cells, the glycocalyx was separated from the cell surface by a clear, electron-transparent area. Cells, removed at 6 h, were covered with a sparse glycocalyx of fine fibers 0.2 to 0.3 microm from the cell surface. Strains 82-25 and L101, incubated for 2 h in heat-inactivated ovine or bovine serum or in heat-inactivated ovine or bovine serum depleted of gamma globulin by protein G affinity chromatography, were also covered with a glycocalyx. The glycocalyx did not bind protein A-colloidal gold and therefore did not contain aggregates of accumulated antibody. Strains 82-25 and L101 were incubated individually for 2 h in 10 mM sodium phosphate buffer (pH 7.2) containing 0.14 M NaCl, 0.5 mM CaCl2, and 0.15 mM MgCl2 or with this buffer and either 25% heat-inactivated, gamma globulin-depleted ovine serum or 25% heat-inactivated, gamma globulin-depleted bovine serum. Agglutination profiles were then determined with 17 lectins in 10 mM HEPES-buffered saline (pH 8.4) with 0.1 mM CaCl2 and 0.08% sodium azide. Profiles did not vary with 10 of 17 lectins. However, profiles did vary with peanut agglutinin, Phaseolus vulgaris leucoagglutinin, Sophora japonica agglutinin, Maackia amurensis lectin II, Narcissus pseudonarcissus (daffodil) lectin, Griffonia simplicifolia lectin I, and Pisum sativum agglutinin. Altered profiles indicate a change in the bacterial cell surface, possibly by adsorption or alteration of surface carbohydrate moieties by serum constituents.

Genetic Characterization of Two Phenotypically Distinct North American Ovine Lentiviruses and Their Possible Origin from Caprine Arthritis-Encephalitis Virus

Ovine and caprine lentiviruses are closely related genetically and antigenically although the diseases that these viruses cause in their respective host animals can vary greatly. In sheep, syndromes consist primarily of interstitial pneumonia with rare occurrences of arthritis and encephalitis, whereas in goats, the disease expresses mainly as arthritis in adult animals with rare cases of encephalitis in newborns. Experimentally, viruses from either sheep or goats can infect animals of the reciprocal species and many field strains of ovine lentivirus have biological properties similar to those of caprine viruses. However, a molecular correlation for the phenotypic differences between ovine and caprine lentivirus strains is unknown. To investigate this, we examined genetic characteristics of two phenotypically distinct North American ovine lentiviruses. Nucleotide sequence analysis of the envelope regions from virus strains 85/34 and 84/28 showed that despite significant biological differences, these viruses are closely related to each other and are genotypically more homologous to caprine arthritis-encephalitis virus (CAEV) than to visna virus of sheep. Furthermore, analysis of the nucleotide substitutions in theirenvregions indicated that when differences between the two ovine viruses and CAEV were found, the changes often resulted in nucleotides homologous with visna virus. These results suggest that the two field strains of ovine lentivirus may have originated from a cross-species infection of sheep by a CAEV-like virus and, evolution of their genomes toward that of ovine lentivirus may be reflective of adaptation of these viruses to the new ovine host.