Search

Neonatal calf diarrhea virus (a bovine rotavirus) formed distinct plaques in monolayers of MA-104 cells, an established macacus rhesus monkey kidney cell line, when diethylaminoethyl dextran and trypsin were included in the overlay medium. By using this plaque assay method, titration of neutralizing antibody to neonatal calf diarrhea virus was made feasible. It was demonstrated that some human sera contained neutralizing antibody to this agent.

Two groups of 3-month old calves were immunized intramuscularly with attenuated bovine rotavirus and boosted 21 and 42 days later. The first group of three calves were vaccinated with live virus emulsified with incomplete Freund's adjuvant (IFA) and the second group was immunized with live virus suspended in phosphate buffered saline (PBS). Three other calves, serving as controls, were inoculated with PBS emulsified with IFA. The specific cell-mediated and antibody responses of the animals were studied. Preliminary analysis of in vitro peripheral blood lymphocyte transformation to bovine rotavirus determined optimal conditions as: 96 h culture period, 5 × 10 5 cells per culture in RPMI 1640 medium containing 10% heat-inactivated bovine fetal serum and the use of inactivated virus in the cell culture at a concentration of 5 × 10 6 median tissue culture infective dose before inactivation. Specific blastic stimulation was observed on calves immunized with the rotavirus emulsified with IFA after the second and third vaccine inoculation with stimulation index values varying from 2.00 to 5.73. Serum neutralizing antibody titers of 1 25,600 were also induced in the same calves. Calves immunized with rotavirus-PBS suspension developed a mean antibody titer of 1 1,600 , but showed no specific lymphocyte stimulation. No increase in specific immune responses was detected in the control animals.

Genomic variations in electropherotypes of bovine rotavirus were analyzed in dairy farms. A unique electropherotype was detected in each farm which persisted at least for a year. In one farm a dual infection and a second electropherotype were detected.

An indirect immunoperoxidase technique has been used to identify enteropathogens in formol-sublimate fixed paraffin embedded sections of calf intestine. Infections with bovine rotavirus, bovine coronavirus, Newbury agent SRV -1, and K99+ Escherichia coli have been detected in the intestines from experimentally infected and conventially reared diarrhoeic or normal calves. The ability to visualize enteropathogenic agents in histological sections resulted in the demonstration of virus infected cells at sites not previously shown to be infected using the immunofluorescence technique.

An outbreak of a pneumoenteric disease occurred in neonates in a zoo nursery. Four of seven affected animals died. Rotaviruses were observed in the feces of an affected 4-day old impala (Aepyceros melampus), a Thomson's gazelle (Gazella thomsonii) and an addax (Addax nasomaculatus). Encapsulated Escherichia coli also were isolated from the feces. The recovered rotaviruses were antigenically related to bovine rotavirus. A bovine rotavirus vaccine was given orally and no adverse effects were noted.

The structure of tubes of reassembled nucleocapsid protein (VP6) from bovine rotavirus (BRV) was determined using optical diffraction of electron micrographs. The tubes consist of a five-start helix of hexagons, with 38 hexagons per helix in a true repeat of three turns. The morphological subunits comprising the hexagons are probably elongated trimers. The structure of naturally occurring tubes (D. Chasey and J. Labram, 1983, J. Gen. Virol. 64, 863-872) was also examined and shown to be similar but not identical to that of tubes assembled in vitro. Considerations of the assembly process are discussed.

Two cytopathogenic bovine rotavirus strains were isolated. The infectivity of both isolates was relatively stable at pH 3.0 and resistant to ether. Their replication was not affected by 5-iodo-2'-deoxyuridine. The new isolates shared immunofluorescent antigen with the Lincoln strain of bovine rotavirus. By neutralization test, however, these strains were clearly distinguished from one another.

In a randomized, double-blind, placebo-controlled trial, 331 infants aged 6 to 12 months received orally, at an interval of 1 month, either two doses of live attenuated bovine rotavirus vaccine strain RIT 4237 or equivalent placebo. The vaccinations were carried out during September to November, a non-rotavirus season; only three cases of rotavirus diarrhea occurred in the study group before the vaccinations were completed. During the epidemic season from December to May, 31 patients with clinically significant rotavirus diarrhea required therapy. Five of these were among the 168 vaccine recipients, and 26 among the 160 placebo recipients (P less than 0.001), giving a vaccine protection rate of 82%. The incidence of clinically significant diarrhea from all causes was reduced by 76% in the vaccinees. As determined by an enzyme immunoassay antibody test with homologous virus antigen, seroconversion after vaccination was obtained in 53% of the initially seronegative infants. Clinical protection correlated well with seroconversion, but the vaccinees who failed to seroconvert also had less rotavirus diarrhea than the placebo recipients, suggesting that immunity may be mediated by factors other than serum EIA antibody. Seventeen of the 23 rotavirus isolates in the epidemic season that were typed were of serotype 1, two were of serotype 2, and four were of serotype 3. The protection rates against clinically significant diarrhea were 72%, 100%, and 100% for serotypes 1, 2, and 3, respectively. We conclude that epidemic infantile winter diarrhea associated with human rotaviruses can be significantly reduced by vaccination with the live attenuated RIT 4237 bovine rotavirus vaccine before the epidemic season.

Three cytopathic rotavirus isolates were recovered from young rabbits affected by an enteric syndrome. The three isolates, when compared by cross serum-neutralization tests, were found to be of the same serotype. Cross neutralization occurred also between a representative of the rabbit isolates and one strain of bovine rotavirus.

The growth characteristics in MDBK cells of a calf rotavirus isolated in Northern Ireland are described. Of a range of cell cultures tested, the virus grew in secondary bovine kidney and MDBK cells, but consistently produced a CPE only in MDBK cells. The CPE consisted of cytoplasmic vacuolation, development of eosinophilic intracytoplasmic inclusions, and degeneration and detachment of cells from the monolayer. The onset of CPE was more rapid and its effects more severe in rolled cultures than stationary cultures. Immunofluorescent staining showed that the rotavirus was antigenically unrelated to avian and mammalian reoviruses. There was no significant difference in virus growth over the pH range 6.5 to 8.4.

Summary Three types of regularly constructed assembly have been observed by electron microscopy of rotavirus-containing faeces from naturally infected cattle. Two of the structures, designated rotatube 1 and rotatube 2 respectively, are tubular in nature, and the third, designated rotatube 3, takes the form of large relatively disorganized sheets of material exhibiting, in some areas, tubular characteristics. Rotatube 1 is a ‘wide’ tube of approximately 80 nm diameter, the wall of which is composed of a surface lattice of hexagonally arranged subunits. Rotatube 2 is a ‘narrow’ tube, half the diameter of the wide tube, and does not exhibit a strictly hexagonal surface lattice. The sheets of rotatube 3 material are composed of subunits arranged on an hexagonal lattice identical with that of rotatube 1. The dimensions and general structural characteristics of the three types of assembly indicate that they are composed of rotavirus capsid protein.

After experimental contamination of bovine raw and heat-treated milks with bovine rotavirus and coronavirus strains, we observed a strong viral inhibition only with raw milks, from which virus recovery was 5 × 10-4%. Between 30% and 80% of the virus was recovered from the heat-treated milks, depending on the level of inoculation. The antiviral substance is heat-labile (destroyed within 30 min at 100°C), precipitated by ammonium sulfate and filtrable (0.45 μm Millipore membrane). It also has neutralizing activity on tissue culture.

The nucleocapsid protein (VP6) of bovine rotavirus was purified from in vitro-derived single shelled particles by CaCl2 or LiCl treatment. The protein exhibits polymorphism. Specifically, hexamers and small hexagonal lattices were present in many of the samples. Tubular particles formed between pH 5.0 and 9.0 were moderately stable to changes in temperature and ionic strength and were shown to be composed of nucleocapsid protein. Their formation is fully reversible. Spherical particles resembling single-shelled virus formed at pH 4.0. A novel structure in the form of sheets composed of a small-hole lattice formed in samples shifted from pH 6.0 to 4.0. The results demonstrate the importance of the nucleocapsid protein and of protein-protein interactions for rotavirus assembly.

Using plaque assay on MA 104 cells, four strains of bovine rotavirus were compared: the attenuated American strain NCDV, and three virulent strains isolated in Canada (PQ) or in Belgium (S14 and S 77). The attenuated strain (NCDV) formed smaller plaques than the three others. The plaque size may thus be used as a marker for this strain. The Belgian strain S 77 formed the largest plaques and no significant differences could be found between the Canadian strain PQ and the second Belgian strain S 14. On BSC-1 cells, the Canadian strain PQ formed much smaller plaques than on MA 104 cells.

A total of 288 serum samples were collected from 12 species of animals in various localities of Japan from 1975 to 1977. Neutralizing antibody to bovine rotavirus was found in serum samples from all the species, viz., horses, cattle, sheep, goats, pigs, dogs, rabbits, guinea pigs, rats, mice, chickens and human beings. The incidence of neutralizing antibody in titers of 1 : 2 or higher ranged from 31 to 100%, and high incidences exceeding 70% were obtained in horses, cattle, sheep, pigs, dogs, rabbits and human beings. High titers were most common in horses, cattle, sheep and pigs. These serological results suggest that rotaviruses occur commonly in these species of animals.

Using the plaque assay or the CPE test (cytopathogenic effect), we investigated the action of human, simian (rhesus), bovine and murine interferons on bovinerotavirus adapted to grow on established Rhesus monkey kidney cell line (MA 104) or Georgia Bovine Kidney cell line (GBK). Except for the murine interferon we used, which had no antiviral effect at all, the different interferons tested were clearly active.

A direct microplate ELISA for the detection and quantitation of bovine rotavirus is described. The assay permitted the detection of less than 5 ng virus/ml in purified preparations and in faecal samples, providing that the samples contained enough virus so that the assay could be performed at dilutions ⩾ 1:1000. In spite of a reduction in the sensitivity of the test at high concentrations of faecal material, the direct assay proved, in practice, to be more efficient than was electron microscopy. Results on the excretion of rotavirus in the course of infections and on the incidence of rotavirus infections among calves and older animals are presented and discussed.

Gamma globulin fraction was obtained from serum or colostrum whey of cows vaccinated with bovine rotavirus type 1 and bovine coronavirus and reconstituted artificial colostrum (AC). A field study was conducted in 2 beef herds, where the prevalence of both viruses had been confirmed, in early spring when spontaneous diarrhea was prevalent. At the time of birth calves were divided equally into 2 groups. One group was fed an AC diet additionally 3 times at 2 day-intervals soon after birth. The second group was used as a control. The supply of AC did not entirely eliminate any clinical disease. There were some differences between the AC and control groups in the age in days of onset, duration, and severity of diarrhea. No differences were fround in the average level of circulating immunoglobulin or antibody in the calf serum between the 2 groups. In a twin the protective effect of the AC diet was directly observed on calf serum immunoglobulin level and on symptoms. The additional feeding of the AC diet would be useful for preventing clinical diarrhea in newborn calves.

Serum neutralization tests conducted by microtiter procedure on 2970 serum samples from calves, heifers and adult cows from representative regions of Italy indicate that rotaviruses, and the infection which they cause, existed in Italy long before the virus was isolated. At the present time the infection is distributed fairly uniformly throughout the cattle population with both sexes and all age groups being equally susceptible.

Ten young dogs were experimentally infected twice with different isolates of bovine rotavirus and 2 uninfected dogs were kept in contact with them. None of the animals developed diarrhoea, but all of them excreted rotavirus in their faeces over a period of up to 10 days after each inoculation, as shown by counterimmunoelectro-osmophoresis and virus isolation. Dogs may thus play a role in the epizootiology of rotavirus diarrhoea in calves. Seroconversion occurred in 6 of the 10 infected dogs but in neither of the 2 contact controls.

Enterovirus-like particles from feces of calves are a frequent source of contamination of bovine rotavirus isolates. A study of plaque formation using BSC-1 cells indicated differences in behaviour of the viruses which could be used for differentiation and purification. The enterovirus-like particles produced well-defined plaques earlier and reached their optimal size much more rapidly than did the rotavirus. Furthermore, plaques produced by bovine enterovirus-like particles were significantly larger than those of bovine rotavirus. The viral cytopathic effects on the cells within the plaques were also characteristic for each virus.

Gamma-globulin fraction was obtained from the blood serum of a steer and colostrum wheys of cows vaccinated against bovine rotavirus (BRV) and bovine coronavirus (BCV), and emulsified with vegetative oil and other ingredients to reconstitute artificial colostrum (AC). The efficacy of AC was studied for protection of colostrum-deprived calves against experimental exposure to BRV and BCV at 22 or 25 hr of age. Calves Nos. 1 and 2 were orally challenged with the cell cultures of BRV and BCV, and Nos. 3, 4 and 5 with BCV; all the inocula were in combination with Escherichia coli K99(+) Ent(+). Calves Nos. 1 and 3, fed no AC, developed severe diarrhea. On the contrary, No. 2, fed AC several times before and after the challenge, and No. 5, once fed AC within 30 min after the challenge, developed no diarrhea. No. 4, once fed AC 4 hr after the challenge, showed only transient diearrhea. The severity and prevention of diarrhea related generally with immunoglobulin levels and antiviral antibody titers, derived from the administered AC, in the serum of the animals at about 100 hr of age. The results obtained indicated that AC has protective effects in calves against the exposure with BRV and/or BCV.

Summary Various growth conditions for the UK strain of bovine rotavirus in cell cultures were examined. The importance of trypsin treatment throughout the cultivation for the virus titer obtained was confirmed. The absence of serum in the maintenance medium also improved the titer. The cell types that gave the highest titer (measured by fluorescence foci) were secondary calf kidney cells and BGM cells. When samples from cases of calf diarrhea were examined, the best results were obtained by direct ELISA technique on fecal suspensions. For demonstration of virus in cell cultures immunfluorescence, immunperoxidase technique, acridine orange staining, ELISA and CPE were employed. Zusammenfassung Untersuchungen uber das Wachstum von bovinem Rotavirus in Zellkulturen Es wurden verschiedene Wachstumsbedingungen fur den UK Stamm von bovinem Rotavirus in Zellkulturen gepruft. Die Wichtigkeit der Trypsinbehandlung wahrend der Anzuchtung fur den zu erreichenden Virustiter wurde bestatigt. Ein Erhaltungsmedium ohne Serum verbesserte den Titer ebenfalls. Die Zellart, die den hochsten Titer ermoglichte (gemessen mit der Fluoreszenz-Zellzahl-Methode) waren sekundare Kalbernierenzellen und BGM-Zellen. Bei Untersuchungen von Proben aus Fallen mit Kalberdurchfall brachte die ELISA-Technik mit Kotaufschwemmungen die besten Ergebnisse. Fur das Nachweisen des Virus in Zellkulturen wurden die Immunfluoreszenz, die Immunperoxidase-Technik, die Akridin-Orange-Farbung, der ELISA und der CPE verwendet. Resume Recherches sur la croissance du Rotavirus bovin en cultures cellulaires Differentes conditions de croissances pour la souche UK du Rotavirus bovin ont ete testees en cultures cellulaires. L'importance du traitement par la trypsine durant l'ensemencement pour atteindre le titre viral a ete confirmee. Un milieu de conservation sans serum a egalement ameliore le titre. Les especes cellulaires qui ont donne les titres les plus eleves (mesures avec la methode du comptage cellulaire par la fluorescence) furent des cellules renales secondaires de veaux et des cellules BGM. La technique ELISA avec des suspensions de matieres fecales a donne les meilleurs resultats lors des examens d'echantillons de cas de diarrhee des veaux. On a utilise l'immunfluorescence, la technique de l'immunperoxydase, la coloration a l'acridine-orange, l'ELISA et CPE pour la representation du virus dans les cultures cellulaires. Resumen Estudios sobre el crecimiento de rotavirus bovinos en cultivos celulares Se analizaron varias condiciones de crecimiento para la estirpe UK de rotavirus bovino en cultivos celulares. Pudo confirmarse la importancia del tratamiento a base de tripsina durante la cultivacion para alcanzar titulo de virus. Un medio de sostenimiento sin suero sanguineo tambien mejoro los titulos. La especie celular que hizo posible los titulos maximos (medidos con la tecnica de recuento celular en fluorescencia) eran celulas secundarias de rinones de ternero y celulas BGM. En los estudios de indagacion con muestras de casos de diarreas en terneros, se lograron los mejores resultados empleando la tecnica ELISA con suspensiones de estiercol. Para representar el virus en cultivos celulares se utilizaron la inmunofluorescencia, coloracion a base de acridina-naranja, la ELISA y el CPE.

The genomic RNA patterns of six different bovine rotavirus isolates were analyzed on high-percentage polyacrylamide gels (12.5, 13.6, and 17.5%). In contrast to the RNA patterns exhibited by conventional gel systems, those on the high-percentage gels showed an improvement in segment resolution which consequently aided in the detection of extensive band splitting in these patterns. The ability to clone out various electrophoretically distinct virus subpopulations from each of the six isolates provided an explanation for the band splitting detected by the high-resolution gels. The significance of the coexistence of genetically distinct rotavirus populations within a single host is discussed.

Survey of rotavirus was conducted in 40 fecal samples which were divided into 4 groups according to diarrheal conditions to clarify the relationship between rotavirus and foals with diarrhea. Particles characteristic of rotavirus were directly detected by electron microscopy from 5 of 14 fecal samples collected from foals with acute diarrhea. Moreover, rotaviruses were isolated from 4 of 5 fecal samples with MA-104 cells and with trypsin treatment, and were capable of being successively passaged in these cells. On the other hand, no rotavirus was detected in 26 fecal samples collected from foals with various non-acute diarrhea. In the cross serum neutralization test, 4 isolated strains were antigenically recognized as the same serotype, which was slightly differed from BI strain of equine rotavirus and clearly separated from Lincoln strain of bovine rotavirus antigenically. From these results, it was revealed that rotavirus was closely related only to acute diarrhea in foals. Moreover, it was confirmed that equine rotavirus in field cases could be isolated in MA-104 cells with trypsin treatment.

Summary The composition and topography of the structural polypeptides of bovine rotavirus was studied by polyacrylamide gel electrophoresis of radioactively labelled virus grown in LLC-MK2 cells and by lactoperoxidase-catalysed iodination of single- and double-capsid particles. Bovine rotavirus was found to possess at least six structural polypeptides, three of them associated with the inner capsid (p102K, p91K and p45K) and the others with the outer capsid (p84K, p37K and p34K). The most abundant polypeptide of the inner capsid was p45K, which accounted for approx. 80% of the protein mass, followed by p91K (approx. 20% of the protein mass) and p102K (approx. 1% of the protein mass). Polypeptide 45K is not readily available for iodination, indicating that it is partially covered by p91K, which is the most exposed polypeptide of the inner capsid. The number of polypeptide molecules per single capsid particle (calculated on the basis of an RNA content of 16%) was estimated to be approx. 6 molecules of p102K, 140 of p91K and 989 of p45K. The stoichiometry and degree of exposure of outer capsid polypeptides was more difficult to establish, even when it appears that p84K and p34K are the most exposed components.

The involvement of light (L) and dense (D) bovine rotavirus particle types during virus replication has been studied. It was found that infectious parental L virions are uncoated in vivo to a particle similar to native D particles. Differences in the rate of synthesis and relative yields of L and D particles in MDBK and MA-104 cells have been detected. Results from pulse-chase labeling experiments indicate that D particles serve as morphogenic precursors to the complete L virion.

Faecal samples or intestinal contents from 92 fatal cases of neonatal diarrhoea in calves were tested for rotavirus by the following methods. Electron microscopy (EM) was performed as previously described, by negative staining of bands obtained after centrifugation of clarified faecal suspensions on CsCl-gradients (Grauballe et al., 1977). Detection of fluorescent antigen by the use of FITC-conjugated rabbit anti bovine rotavirus antibodies (FA) was performed in two ways: either by direct staining of smears from intestinal contents or by staining of primary bovine kidney cells previously inoculated with the specimen as described (Meyling, 1974). Immunoelectro-osmophoresis (IEOP) and enzyme-linked immuno-sorbent assay (ELISA) were performed according to the manuals presented at this meeting, using the same antibodies for both assays, i.e. second generation poly-specific antibodies to human rotavirus prepared in rabbits by injection of immunoprecipitates as previously described (Grauballe et al., 1979).

Thirty-six showed a very strong (+ + + +) reaction, 8 a mod-erately strong (+ + +) reaction, 3 a weak (+ +) reaction, and14 a very weak (+) reaction. Of the animals where age wasreported, 24% of the positive tests were in calves less than6 days of age, 46% were in calves between 6 and 10 days ofage, and 32% were in calves older than 10 days. Polyacryl-amide gel electrophoresis (PAGE) was performed on all 142fecal samples using established techniques.

Antibodies were demonstrated in the small intestine, in faecal material, and in serum from calves which had been infected with different strains of bovine rotavirus at 6–9 days of age.

Enzyme-linked immunosorbent assay (ELISA) was compared with electron microscopy in the examination of faeces from experimental calves and showed 100 per cent agreement in the detection of 19 bovine coronavirus and 15 bovine rotavirus electron microscope positive samples. In a limited field survey of calf diarrhoea 75 selected faeces were examined independently by ELISA and electron microscopy and the agreement between the two tests was 95 per cent for coronavirus and 84 per cent for rotavirus. A further comparison was made with 74 samples submitted for routine diagnosis and this yielded agreements of 82 per cent (coronavirus) and 89 per cent (rotavirus). Factors contributing to discrepant results were examined and the relative advantages and disadvantages of the two tests for routine detection of these enteric viruses are discussed.

We demonstrated by electron microscopy that three different forms of tubular structures are present both within infected cells and in cultured fluid of bovine rotavirus in a tissue culture system.

Three rotavirus strains of bovine, simian and porcine origin, respectively, were compared. The 3 viruses induced a classic rotavirul infection in newborn, conventionally reared calves. The cross neutralization tests revealed an antigenic identity of simian and porcine rotaviruses and a slight serologic correlation of these two viruses with the bovine rotavirus strain. However, in reciprocal cross protection tests carried out in calves, the simian rotavirus antiserum afforded weak protection to challenge infection with either the porcine or the bovine viruses. By contrast, the protective level of the bovine and the porcine rotavirus antisera was relatively high. It was speculated that the 81/36F bovine rotavirus could be considered, tentatively, as an antigenic reassortant rotavirus strain.

Vaccination of humans against rotavirus (RV) diarrhea may be accomplished by oral immunization with attenuated animal strains known to be antigenically very similar to human strains. To define better the degree of infectivity in nature of these animal strains for humans, we conducted surveillance for RV infection/diarrhea in 180 farm workers, their 161 family contacts, and the 566 animals (512 cattle, 35 pigs, and 19 sheep) on 14 farms in rural Panama. No correlation between the high infection rates in farm workers (72^0) and their family contacts (78^o) and in cattle (56^0) could be demonstrated. Heads of families with four or more children with RV infection experienced a twofold greater rate of RV infection compared with heads of families of similar size without RV infection. Despite the close similarity between human and bovine RV, in Panama intrafamilial (particularly child-to-child or child-to-parent) rather than interspecies transmission appeared to be the most important route for the spread of this highly infectious virus.

Background Group A rotaviruses (RVA) are the main cause of neonatal calve diarrhea (NCD) in Morocco. In this study, we isolated RVA strains from NCD clinical samples in order to support RVA disease control in Morocco. This isolation process constitutes a first step toward vaccine development. Methods Thirteen fecal samples were obtained from calves with a single episode of neonate calf diarrhea at three different dairies and two samples were collected from field during a severe NCD outbreak. Diagnosis of RVA infection was based on fecal immune-chromatographic rapid test and further evaluated for their hemagglutination (HA) activity. RVA isolation was carried out on MA104 cells after inoculates were treated with different concentrations of trypsin TPCK. All RVA isolates were confirmed by LSI VetMAX™ Triplex Ruminant Rotavirus & Coronavirus Real-Time PCR kit. G and P typing were determined by direct sequencing of the VP4 and VP7 amplicons. Results RVA isolation was achieved for nine clinical samples following one or two passages (60 %) and was properly depended on HA activity and trypsin treatment of inoculates. The first sign of CPE detected consisted of increased cell granularity, obscure cell boundaries, cell rounding, and eventual degeneration and detachment of cells. At lower TPCK concentration (3–10 μg/inoculum), no changes at the cellular level were observed, while cells activated with 25–30 μg of trypsin/inoculums, they degenerated and trypsin cytotoxicity was enhanced. Appreciable changes in cell’s morphology were detected with optimal trypsin concentration of 15–20 μg trypsin/inoculums. Data from qRT-PCR confirmed that unsuccessful cultivations have No-Ct, and all nine isolates have Ct values ranged between 12.17 and 24.69. Analysis sequencing revealed that field isolates were of G6 P[5] serotype and isolates from the dairy NCD samples were of G10 P[14] serotype. Conclusions To our knowledge, this is the first study in Morocco which reports the circulation of G10P[14] in NCD on dairy farms and G6P[5] in the field. Our study constitutes a crucial and a necessary step allowing preventive and veterinary medicine to support RVA disease controls in the country.

The first clinical trial of RIT 4237 rotavirus vaccine indicated that one oral vaccination of infants aged 8-11 months will induce 88% protection against rotavirus diarrhoea over an epidemic season of rotavirus ( Vesikari et al, Lancet i:977, 1984). A second placebo-controlled field trial involving 347 children aged 6-12 months was started in September 1983. Postvaccination sera were collected from 328 children in December 1983 before the rotavirus epidemic season and third sera from 291 children in May 1984 after rotavirus season. A fourth serum will be collected in 1985. Before vaccination 90% of the children were seronegative for rotavirus, and 53% of the vaccinees but none of the placebo recipients seroconverted by rotavirus ELISA-IgG. During the first rotavirus season 44% of the seronegative placebo recipients and 63% of the still seronegative vaccinees showed seroconversion indicative of primary rotavirus infection. This was associated with clinical diarrhoea in 26 cases (43%) in the placebo recipients and 4 cases (11%) in the vaccinees (p 0.001). Altogether the vaccine protection rate for rotavirus diarrhoea was 81% in the first season. During the second rotavirus winter epidemic as of April 15, 1985, 7 cases of rotavirus diarrhoea have been diagnosed in the placebo group and 1 in the vaccine group (protection rate 85%). These results suggest that the RIT 4237 rotavirus vaccine will induce protection against rotavirus diarrhoea up to the age of 3 years.

12. LONG TERM PROTECTION AGAINST SEVERE ROTAVIRUS DIARRHOEA BY A SINGLE DOSE OF BOVINE ROTAVIRUS VACCINE STRAIN RIT 4237 GIVEN IN THE NEONATAL PERIOD.