Enhanced production of antibody with specific antigen.

On inoculation of nonspecific stimulator of immunity (NSI), prepared from Mycobacterium phlei (M. phlei), simultaneously along with sheep pox virus (SPV) in sheep, the recipient has exhibited appreciable level of SPV specific antibody as early as on 10th day which reached at peak level on 20th day and remained unaltered on 30th day of postimmunisation as evinced by serum neutralisation test (SNT), enzyme linked immunosorbant assay (ELISA) indirect, fluorescent antibody technique (FAT) indirect, counter immunoelectrophoresis (CIEP) and finally by virulent SPV challenge. On the contrary, sheep, when immunised with SPV only could not produce appreciable level of antibody on 10th day but did so on 20th day of inoculation. SPV and NSI immunised sheep produced enhanced protection against virulent SPV challenge in comparison with sheep immunised with SPV only. Healthy control sheep, however, could not resist challenge.     

Sequence analysis of attachment gene of lumpy skin disease and sheep poxviruses

In Egypt, protection of cattle against lumpy skin disease (LSD) was carried out using a sheep poxvirus (Kenyan strain) vaccination strategy. In the present study 15 skin nodules from LSD suspected cows and 5 scab samples from sheep pox (SP) suspected sheep were collected. Hyperimmune rabbit sera to Lumpy skin disease virus (LSDV)/Ismailyia88 strain and sheep pox virus (SPV)/ Kenyan vaccinal strain were prepared. The causative agent in the collected samples was identified using immunoflourescence (IF) and immunoperoxidase techniques. Of the 15 skin nodules suspected of LSD, 10 showed a positive reaction and 3 out of 5 skin scabs suspected of sheeppox were found to be positive. An antigenic correlation between field skin isolate of LSDV, tissue culture adapted LSDV/Ismailyia88 strain, field skin isolate of SPV and SPV/Kenyan vaccinal strain was studied using prepared hyperimmune sera. Also, nucleotide sequence of the PCR amplified attachment gene fragments of field skin isolate of LSDV, tissue culture adapted LSDV/Ismailyia88 strain, field skin isolate of SPV and SPV /Kenyan vaccinal strain were compared. The results revealed that the four used viruses were antigenically identical. Sequence analysis indicated that field skin LSDV isolate is more related to tissue culture adapted LSDV/Ismailyia88 strain than to vaccinal SPV/ Kenyan strain and the skin isolate of SPV is more closely related to field skin isolate of LSDV than to SPV/Kenyan vaccinal strain. Thus, further study should be applied on the advantage of a LSD vaccine prepared from LSDV in protection of cattle against LSD compared to the commonly used sheep pox vaccine.     

Differences in the capacity of HLA sera to react with T- and B-lymphocyte populations]

A study was made of perculiarities attending the reaction of the HLA-sera with the T- and B-lymphocytes isolated from human blood. Lymphocytes were separated by removal of one of the cell subpopulation. T-lymphocytes were separated by the method of rosette-formation with sheep erythrocytes, with subsequent gradient density centrifugation. B-lymphocytes were separated similarly with the aid of rosette-formation with allogenous Rh-positive erythrocytes sensitized with Rh-sera with incomplete antibodies, and also sorption of B-lymphocytes on synthetic fiber. The cytotoxic activity of HLA-sera decreased after the removal of B-cells. But removal of T-lymphocytes was not accompanied by any reduction in the lymphocytotoxic activity. It is suggested that B-lymphocytes contained on their surface more HLA determinants than T-lymphocytes.     

B-lymphocytes as Key Players in Chemical-Induced Asthma

T-lymphocytes and B-lymphocytes are key players in allergic asthma, with B-lymphocytes producing antigen-specific immunoglobulins E (IgE). We used a mouse model of chemical-induced asthma and transferred B-lymphocytes from sensitized animals into naïve wild type mice, B-lymphocyte knock-out (B-KO) mice or severe combined immunodeficiency (SCID) mice. On days 1 and 8, BALB/c mice were dermally sensitized with 0.3% toluene diisocyanate (TDI) (20µl/ear). On day 15, mice were euthanized and the auricular lymph nodes isolated. B-lymphocytes (CD19⁺) were separated from the whole cell suspension and 175,000 cells were injected in the tail vein of naïve wild type, B-KO or SCID mice. Three days later, the mice received a single oropharyngeal challenge with 0.01% TDI (20µl) or vehicle (acetone/olive oil (AOO)) (controls). Airway reactivity to methacholine and total and differential cell counts in the bronchoalveolar lavage (BAL) fluid were measured 24 hours after challenge. B-lymphocytes of AOO or TDI-sensitized mice were characterized for the expression of surface markers and production of cytokines. We found that transfer of B-cells obtained from mice dermally sensitized to toluene diisocyanate (TDI) into naïve wild type mice, B-KO mice or SCID mice led, within three days, to an acute asthma-like phenotype after an airway challenge with TDI. This response was specific and independent of IgE. These B-lymphocytes showed antigen presenting capacities (CD80/CD86 and CD40) and consisted of B effector (Be)2- (IL-4) and Be1-lymphocytes (IFN-γ). The transferred B-lymphocytes were visualized near large airways, 24 hours after TDI challenge. Thus, B-lymphocytes can provoke an asthmatic response without the action of T-lymphocytes and without major involvement of IgE.     

In vitro bioassay of sheep gastrointestinal mucus for nematode paralysing activity mediated by substances with some properties characteristic of SRS-A

A bioassay is described for determining the inhibition of nematode larval migration from agar by substances exerting a paralysing action.In the assay, larval migration was completely inhibited by the anthelmintic levamisole (25 μg/ml) whereas biogenic amines, and prostaglandins E₁ and E₂ at 50 μg/ml, were without effect. Mucus from the gastrointestinal tract of sheep resistant to nematode infection inhibited larval migration by up to 93% whereas mucus from heavily infected sheep or sheep reared helminth free did not significantly inhibit larval migration. Mucus from sheep resistant to Trichostrongylus colubriformis inhibited the migration of larvae of other nematode species.The larval migration inhibitory (LMI) activity of mucus from resistant sheep was associated with components having some properties of slow reacting substance of anaphylaxis (SRS-A).Faecal samples from resistant sheep possessed significantly more LMI activity than faecal samples from heavily infected sheep or sheep reared helminth free. The level of LMI activity in the faeces of sheep undergoing challenge infection may be a useful indicator of the sheep's resistance status.The presence of the larval migration inhibitory activity in sheep mucus is discussed in relation to resistance to infection.     

Effects of delivery method on serological responses of bighorn sheep to a multivalent Pasteurella haemolytica supernatant vaccine

The safety and efficacy of a remotely delivered multivalent Pasteurella haemolytica supernatant vaccine (serotypes A2 and T10) were examined in captive Rocky, Mountain bighorn sheep (Ovis canadensis canadensis). Twenty bighorn sheep were grouped according to baseline leukotoxin neutralizing antibody titers (< or =2 or >2 log2(-1)) and vaccination history (previously vaccinated or unvaccinated). Within these groups, animals were randomly assigned to one of two delivery treatments: hand injection (control) or biobullet implantation. All bighorns received a single dose from the same lot of vaccine (n = 10/treatment); four additional animals were injected intramuscularly with 0.9% saline as unvaccinated sentinels. Mild, transient lameness one day after hand injection or biobullet implantation was the only adverse effect. Serum neutralizing antibody titers to P. haemolytica leukotoxin differed between delivery treatments (P = 0.009) and among baseline titer/vaccination history groups (P = 0.013). Neutralizing titers were higher among hand-injected bighorns. Although neutralizing titers were lower among implanted bighorns than hand-injected controls at 1 wk (P = 0.002) and 2 wk (P = 0.021) after vaccination, seroconversion rates in response to implantation (6/10) and hand injection (9/10) did not differ (P = 0.303). Agglutinating antibody titers to T10 were high and did not vary over time or between delivery treatments. Agglutinating antibody titers to A2 in the hand-injected controls were not different (P > or = 0.07) than those in bighorns vaccinated with biobullet implantation. These data demonstrate that although hand injection elicits higher absolute titers, biobullet implantation may also stimulate effective antibody responses to P. haemolytica supernatant vaccine. Further evaluation of biobullet vaccination against pneumonic pasteurellosis in free-ranging populations of wild bighorn sheep is warranted.     

Stem cell, T- and B-lymphocyte migration in mouse lines that are high and low reactors to sheep erythrocytes]

Migration of stem cells and B-lymphocytes from the bone marrow and of T-lymphocytes from the thymus was studied on special models in mice of the CBA and C57BL lines, responding to sheep erythrocytes oppositely. Genetically-determined differences in the height of the immune response between the CBA and C57BL mice in immunization with sheep erythrocytes depended to a certain extent on different expression of the process of intensification of migration of the stem cells, T- and B-lymphocytes in response to the antigen administration.     

Immunologic responses of domestic and bighorn sheep to a multivalent Pasteurella haemolytica vaccine

The efficacy of a Pasteurella haemolytica vaccine (serotypes A1, A2, and T10) to induce humoral antibodies and alter colonization of the upper respiratory tract by related P. haemolytica spp. strains was evaluated in 10 bighorn (Ovis canadensis canadensis) and 10 domestic (Ovis aries) sheep. Sheep of each species were divided into five pairs based on age and history of respiratory disease. One sheep in each pair was vaccinated twice 2 wk apart with 2 ml of vaccine (VAC group) and the remaining animals (NV group) were injected with 2 ml of sterile saline. Mild, transient lameness was the only observed adverse effect. Blood sera from the sheep were tested for agglutinating antibodies against whole cells of A1, A2, and T10 and for leukotoxin neutralizing antibodies. Antibody titers were expressed as the reciprocal log2 of the highest reactive dilutions. Domestic sheep > 1-yr-old and two bighorn sheep with a history of A1 infection had higher titers throughout the study against A1 cells than domestic sheep < 1-yr-old and bighorns without a history of A1 infection. Both domestic and bighorn sheep had log2 titers of 8 to 12 against A2 cells and 6 to 12 against T10 cells during this time. Bighorn sheep in the VAC group had 2 to 32 fold titer increases for A1 cells by 2 wk post-vaccination (PV) compared to 0 to 2 fold increases in VAC domestic sheep. Two to 16 and 0 to 8 fold increases in antibodies titers to A2 and T10 cells, respectively, were detected in sera of both VAC groups. Sera of bighorn sheep with a history of respiratory disease and all domestic sheep had log2 leukotoxin neutralizing antibody titers of 4 to 14 in contrast to < or = 2 in sera of bighorn sheep without a history of respiratory disease. Neutralizing antibody titers of two bighorns without a history of respiratory disease in the VAC group increased from log2 0 to 5 in one and from 0 to 9 in the other 2 wk PV. Antibody increases in these animals were no longer evident at 16 wk PV while titers of animals with histories of disease remained relatively stable. The types and numbers of Pasteurella spp. isolated from nasal and pharyngeal swabs varied throughout the study without conclusive evidence of suppression of colonization. Although the animals were not experimentally challenged to determine the efficacy of the vaccine, one VAC and one NV bighorn sheep died following introduction of an A2 P. haemolytica strain when leukotoxin neutralizing antibodies had returned to pre-vaccination levels. This vaccine appeared to be safe for use in bighorn sheep and stimulated moderate but transient increases in antibody levels which should provide some protection against naturally occurring disease. A vaccine which would induce production of high and maintained antibodies against multiple strains of P. haemolytica would be valuable for use in bighorn sheep maintained in captivity or when captured for relocation.     

流行性出血热地鼠肾细胞灭活疫苗人体试用细胞免疫反应观察

观察了20位志愿者在接种试验性流行性出血热(EHF)地鼠肾细胞(GHKC)双价灭活疫苗后的细胞免疫反应,并以其体液免疫反应作对照观察。用淋巴细胞转化试验测定细胞免疫水平。结果首针疫苗接种后42天和56天,特异性刺激指数(SSI)和非特异性刺激指数(NSI)均较免疫前显著增高(P_(SSI)<0.001;P_(NSI)<0.02),免疫后SSI累计阳转率为100％,NSI累计阳转率为60％,免疫后6个月二者均降低至正常水平。免疫后56天测定抗体,荧光抗体阳转率为100％;微量感染性中和试验表明,针对家鼠型病毒L99株中和抗体阳转率为95％,而针对野鼠型病毒JR株阳转率为65％。     

Epidemiological and histomorphic studies in sheep infected with hydatid cyst in Taif area

Hydatidosis is a zoonotic disease caused by Echinococcus granulosus larvae, which affects sheep worldwide, especially in rural communities. This study aims to determine the prevalence and structure of hydatid cyst in sheep. A total number of 1,198 sheep in different age groups G1 (<1 year), G2 (1–2 years) and G3 (>2 years) were slaughtered at Taif abattoirs, then examined for the presence of hydatid cysts in lung, liver, and mesentery. Prevalence of hydatid cyst infection in imported sheep (13.0%) was higher than of local sheep (10.2%). Particularly, as per gender, prevalence of imported females (71.9%) was higher than those of local females (28.1%), while that of imported males (66.3%) was higher than those of local males (33.7%). Large sizes of hydatid cysts and fertility recorded in G3 were higher in both local and imported sheep than those of G1 and G2. Morphometric analysis of pathological lesions in liver of all infected sheep showed a significant increase compared to non-infected healthy sheep (have no lesions) (P < 0.001). In addition, for all infected sheep, histochemical investigation with Masson’s trichrome stain showed collagen fibers inside the hydatid cyst capsules and in pericystic region. The collagen fibers content and the cellular laminated membranes took the green color, while immunohistochemical evaluation detected a positive reaction for CD3.     

Fusion proteins encoded by orf 129L of ectromelia and orf A30L of smallpox viruses cross-react with neutralizing monoclonal antibodies

Open reading frame (orf) 129L of ectromelia (EV) and orf A30L of smallpox viruses (SPV) encoding fusion proteins were cloned and expressed in E. coli cells. The recombinant polypeptides (prA30L H pr129L) were purified from cell lysates by Ni-NTA chromatography. Recombinant polypeptides were able to form trimers in buffered saline and they destroyed under treatment with SDS and 2-mercaptoethanol. Reactivity of prA30L, pr129L and orthopoxvirus proteins was analyzed by ELISA and Western blotting with panel of 22 monoclonal antibodies (MAbs) against orthopoxviruses (19 against EV, 2 MAbs against vaccinia virus and 1 Mabs against cowpox virus). This data allowed us to conclude that there are 12 EV-specific epitopes of pr129L and EV fusion proteins, ten orthopox-specific epitopes of EV, VV, CPV fusion proteins, from them 9 orthopox-specific epitopes of prA30L and SPV fusion proteins. Five Mabs, which cross-reacted with orthopox-specific epitopes, were able to neutralize the VV on Vero cells and from them two MAbs has neutralizing activity against smallpox virus. Our findings demonstrate that 129L fusion protein have EV-specific epitopes, that EV 129L and SPV A30L fusion proteins have a several orthopox-specific epitopes to induce a neutralizing antibodies against human pathogenic orthopoxviruses.     

A human lymphoid cell line with receptors for both sheep red blood cells and complement

The human lymphoid cell line MOLT 4, from a patient with acute lymphocytic leukemia, was initially considered to be derived from T lymphocytes, on the basis of rosette formation with sheep erythrocytes (E). This cell line has now also been found to form rosettes with sheep erythrocytes sensitized with rabbit antibody and mouse complement (EAC). Evidence is presented that the formation of both E and EAC rosettes is due to two separate receptors on the MOLT cells: (a) EAC rosettes were formed more rapidly and were more stable than E rosettes; (b) preincubation of MOLT with an EAC membrane preparation inhibited resetting with EAC and not with E; (c) MOLT formed rosettes with EAC prepared from trypsinized E, but did not bind to trypsin-treated E alone. The implications of this finding, in regard to the derivation of this cell line, are discussed.     

Ca2+-Calmodulin Modulates Ion Channel Activity in Storage Protein Vacuoles of Barley Aleurone Cells

Many plant ion channels have been identified, but little is known about how these transporters are regulated. We have investigated the regulation of a slow vacuolar (SV) ion channel in the tonoplast of barley aleurone storage protein vacuoles (SPV) using the patch-clamp technique. SPV were isolated from barley aleurone protoplasts incubated with CaCl2 in the presence or absence of gibberellic acid (GA) or abscisic acid (ABA). A slowly activating, voltage-dependent ion channel was identified in the SPV membrane. Mean channel conductance was 26 pS when 100 mM KCl was on both sides of the membrane, and reversal potential measurements indicated that most of the current was carried by K+. Treatment of protoplasts with GA3 increased whole-vacuole current density compared to SPV isolated from ABA- or CaCl2-treated cells. The opening of the SV channel was sensitive to cytosolic free Ca2+ concentration ([Ca2+]i) between 600 nM and 100 [mu]M, with higher [Ca2+]i resulting in a greater probability of channel opening. SV channel activity was reduced greater than 90% by the calmodulin (CaM) inhibitors W7 and trifluoperazine, suggesting that Ca2+ activates endogenous CaM tightly associated with the membrane. Exogenous CaM partially reversed the inhibitory effects of W7 on SV channel opening. CaM also sensitized the SV channel to Ca2+. In the presence of ~3.5 [mu]M CaM, specific current increased by approximately threefold at 2.5 [mu]M Ca2+ and by more than 13-fold at 10 [mu]M Ca2+. Since [Ca2+]i and the level of CaM increase in barley aleurone cells following exposure to GA, we suggest that Ca2+ and CaM act as signal transduction elements mediating hormone-induced changes in ion channel activity.     

Mechanisms of action of synthetic polyelectrolytes and polyampholytes on the immune response]

We investigated the effect of polyacrilic acid (PAA) on the immune response in mice of various strains on sheep red blood cells and also the influence of poly-2-methyl-5-vinyl-pyridine (PMVY), PAA and their statistical copolymers on antibody-forming cells (AFC) production in cultures of T- and B-lymphocytes in vivo. PAA was seen to increase accumulation of AFC in the spleen of mice depending on their genotypes. PMVP and PAA were found to intensify the cooperating interaction of T- and B-lymphocytes, whereas their copolymers exert quite an opposite effect. The injection of copolymers to the recipients of cooperating T- and B-lymphocytes practically results in the complete elimination of the cooperation effect between T- and B-lymphocytes in the immune response to sheep erythrocytes without cytostatic action of cell proliferation.     

Experimental infection of sheep with Neospora caninum oocysts

The purpose of the present study was to investigate the potential of Neospora caninum oocysts to infect sheep and determine whether N. caninum DNA could be detected by polymerase chain reaction (PCR) assay in blood and brain of sheep after oocyst inoculation. Six ewes were inoculated per os with 10(4) N. caninum oocysts, whereas 2 ewes served as uninoculated controls. All sheep were bled weekly for 7 wk after inoculation. Blood was analyzed for the presence of N. caninum DNA by 2 different PCR assays, as well as for the presence of antibodies to recombinant and native N. caninum antigens. Neospora caninum DNA was detected in 2 sheep as early as 7 days after oocyst inoculation (DAOI). All 6 sheep were PCR positive by 32 days and remained positive until the end of the study at 49 DAOI. Aside from 1 ewe, all sheep inoculated with N. caninum oocysts contained detectable N. caninum DNA in the brain tissue collected at 49 DAOI. Unlike with PCR, no lesion or parasite was detected by immunohistochemistry. Antibodies were detected by enzyme-linked immunosorbent assay, Neospora agglutination test, or immunoblotting to either native or recombinant N. caninum antigens in sheep inoculated with oocysts.     

Multivariate characterization of morphological traits in Burkina Faso sheep

A total of 6440 female sheep from Burkina Faso were scored for seven body measurements and four qualitative morphological traits. Sampling included the three main environmental areas and sheep breeds of Burkina Faso: the Sahel area (Burkina-Sahel sheep), the Sudan-Sahel area (Mossi sheep) and the Sudan area (Djallonké sheep). Canonical analyses showed that differences in body measurements between the Sudan and the Sudan-Sahel sheep were small even though most body traits showed higher average values in the Burkina-Sahel sheep: the shortest Mahalanobis distance was found between the Sudan and the Sudan-Sahel populations (1.54), whilst that between the Sudan and the Sahelian populations was the largest (7.88). Discriminant analysis showed that most Sudan (Djallonké) individuals (60.85%) were classified as Sudan-Sahel (Mossi) individuals whilst most Burkina-Sahel individuals were classified into their environmental area of sampling (89.46%). Correspondence analyses indicated that the Burkina-Sahel sheep population clustered together with dropping ears, black and brown colour patterns and presence of wattles, the Sudan sheep were closely associated with long hair and vertical and curled ears and that the Sudan-Sahel sheep did not have clear associations with qualitative phenotypic traits. At the morphological level, the Sudan-Sahel (Mossi) sheep population can be considered a geographical subpopulation belonging to the Djallonké breed, showing some particularities, namely larger body size, due to the particular environmental condition of the area in which it is managed and a continuous gene flow from Sahelian sheep, The information reported in this study will be the basis for the establishment of further characterization, conservation and selection strategies for Burkina Faso sheep.     

Multivariate characterization of morphological traits in Burkina Faso sheep

A total of 6440 female sheep from Burkina Faso were scored for seven body measurements and four qualitative morphological traits. Sampling included the three main environmental areas and sheep breeds of Burkina Faso: the Sahel area (Burkina-Sahel sheep), the Sudan-Sahel area (Mossi sheep) and the Sudan area (Djallonké sheep). Canonical analyses showed that differences in body measurements between the Sudan and the Sudan-Sahel sheep were small even though most body traits showed higher average values in the Burkina-Sahel sheep: the shortest Mahalanobis distance was found between the Sudan and the Sudan-Sahel populations (1.54), whilst that between the Sudan and the Sahelian populations was the largest (7.88). Discriminant analysis showed that most Sudan (Djallonké) individuals (60.85%) were classified as Sudan-Sahel (Mossi) individuals whilst most Burkina-Sahel individuals were classified into their environmental area of sampling (89.46%). Correspondence analyses indicated that the Burkina-Sahel sheep population clustered together with dropping ears, black and brown colour patterns and presence of wattles, the Sudan sheep were closely associated with long hair and vertical and curled ears and that the Sudan-Sahel sheep did not have clear associations with qualitative phenotypic traits. At the morphological level, the Sudan-Sahel (Mossi) sheep population can be considered a geographical subpopulation belonging to the Djallonké breed, showing some particularities, namely larger body size, due to the particular environmental condition of the area in which it is managed and a continuous gene flow from Sahelian sheep, The information reported in this study will be the basis for the establishment of further characterization, conservation and selection strategies for Burkina Faso sheep.     

Microbial diversity in bighorn sheep revealed by culture-independent methods

We investigated the effectiveness of culture-independent molecular methods for determining host-associated microbial diversity in bighorn sheep (Ovis canadensis). Results from bacterial culture attempts have been the primary source of information on host-associated bacteria, but studies have shown that culture-based results significantly underestimate bacterial diversity in biological samples. To test the effectiveness of culture-independent methods, we extracted DNA from nasal and oropharyngeal swab samples collected from bighorn sheep in four different populations. From these samples, we amplified, cloned, and sequenced small subunit (16S) ribosomal DNA (rDNA) to identify the scope of microbial diversity in bighorn respiratory tracts. Phylogenetic analysis of these rDNA gene sequences revealed organismal diversity an order of magnitude higher than was determined by culture methods. Pasteurellaceae bacteria were the most diverse phylogenetic group in live bighorn sheep, and members of bacterial genera often associated with respiratory disease were found in all the samples. Culture-independent methods were also able to directly detect leukotoxin (lktA) gene sequences in swab and lung tissue samples. Overall, our results show the power of culture-independent molecular methods for identifying microbial diversity in bighorn sheep and the potential for these methods to detect the presence of virulence genes in biological samples.     

Human immunodeficiency virus type 1 primary isolate neutralization resistance is associated with the syncytium-inducing phenotype and lower CD4 cell counts in subtype CRF01_AE-infected patients

A number of human immunodeficiency virus type 1 (HIV-1) non-B-subtype products have been developed for present or future vaccine trials; in Thailand, several studies using subtype B and/or CRF01_AE vaccines have been conducted. To better characterize the biologic properties of these subtypes, 70 HIV-1 subtype B and E isolates were phenotyped as syncytium-inducing (SI) or non-syncytium-inducing (NSI) isolates and assessed for sensitivity to neutralizing antibody (NAb). A significantly higher number of NSI subtype E viruses were neutralization sensitive than SI subtype E viruses (P = 0.009), while no association between viral phenotype and sensitivity to NAb was observed for subtype B (P = 0.856), suggesting a difference in the neutralization patterns of subtypes B and E. Strikingly, concurrent CD4 T-cell numbers were significantly lower for subtype E-infected patients whose isolates were more resistant to NAb, both for the overall study group (P < 0.001) as well as for the 22 patients with NSI isolates (P = 0.013). Characterization of the evolution of biologic properties of both B and non-B HIV-1 subtypes will provide a clearer understanding of the repertoire of antibodies that must be elicited for a vaccine to be effective against all phenotypes and subtypes.     

Analysis of mixed infection of sheep with bluetongue virus serotypes 10 and 17: evidence for genetic reassortment in the vertebrate host.

Two seronegative sheep were infected intravenously with 10(9) PFU each of bluetongue virus (BTV) serotype 10 and BTV serotype 17. One animal experienced a mild bluetongue-like disease, and both experienced a short-duration viremia and developed neutralizing immune responses to both virus serotypes. Progeny virus was isolated from venous blood from each animal by using conditions in which reassortment could not have occurred during isolation. Electropherotypes were determined for the progeny viruses from the infected sheep, yielding strikingly similar results for the two animals. In both sheep, serotype 10 dominated among the progeny, accounting for 92% of the progeny. Serotype 17 was rarely isolated and accounted for 3% of the progeny analyzed. The remaining 5% of the progeny clones were reassortant and derived genome segments from both serotypes 10 and 17. Analysis of the parental origin of genome segments in the small number of reassortant progeny analyzed suggested that selection of specific genome segments may have occurred in the infected sheep. These data indicate that reassortment of genome segments occurs, at low frequency, in sheep mixedly infected with BTV.