Induction of antibodies binding to the membrane proximal external region of gp36 of HIV-2.

OBJECTIVE: The ability to induce neutralizing antibodies may be the most important feature of an antiretroviral vaccine, preventing infection of target cells and subsequent integration of the virus into the cellular genome where the virus may persist. Broadly neutralizing antibodies directed against conserved epitopes in the membrane proximal external region (MPER) of the transmembrane envelope (TM) protein gp41 of HIV-1 such as the monoclonal antibodies (mAb) 2F5 and mAb 4E10 have been found in infected individuals; however, all attempts to induce such antibodies failed. In individuals infected with HIV-2 such antibodies were not yet reported. METHODS: Two recombinant proteins corresponding to the ectodomain of the TM protein gp36 of HIV-2 were produced, rats were immunized and sera were analyzed for binding and neutralizing antibodies. RESULTS: Although binding antibodies were induced, none of the sera neutralized HIV-2. Most interestingly, epitope mapping showed specific binding of the antibodies to the MPER of gp36, to a region homologous to the binding site of the mAb 4E10 in gp41 of HIV-1. CONCLUSIONS: Although MPER-specific antibodies were induced by vaccination with gp36, these antibodies did not neutralize HIV-2. This is similar to the situation with HIV-1, but in contrast to that with gammaretroviruses.

A neutralization assay for HIV-2 based on measurement of provirus integration by duplex real-time PCR.

Specific, effective and rapid neutralization assays are crucial for the development of an HIV vaccine based on the stimulation of neutralizing antibodies and the development of such an assay for the human immunodeficiency virus-2 (HIV-2) is described. Virus neutralization was measured as the reduction of provirus integration using a duplex real-time PCR with high efficiency (99.4%). This PCR uses primers and a probe specific for the proviral LTR. Amplification and quantitative analysis of the cellular GAPDH gene was carried out in parallel to control for toxic or growth-inhibitory components in the sera. The neutralization assay was used to screen sera from 23 HIV-2 infected patients. 21 sera were able to neutralize HIV-2(60415K), 20 sera neutralized HIV-2(7312A) and 7 sera cross-neutralized HIV-1 IIIB. In contrast, when 14 of these sera were tested in parallel with a conventional neutralization assay based on a p27Gag capture ELISA, only one was found to neutralize HIV-2(60415K) and 11 to neutralize HIV-2(7312A) compared with 12 and 13 sera respectively using the PCR-based assay.

Neutralising antibodies against the transmembrane protein of feline leukaemia virus (FeLV).

Neutralising antibodies specific for feline leukaemia virus (FeLV) were induced by immunisation with recombinant FeLV transmembrane envelope protein p15E. Epitope mapping revealed two epitopes located in similar regions to those previously identified for the porcine endogenous retrovirus (PERV). One of the epitopes has partial homology and both are located in regions corresponding to epitopes recognised by neutralising antibodies in patients infected with HIV-1.

[Observations on the maturity of stillborn calves]. / Bemerkungen zum Reifegrad totgeborener Kälber.

Organ weight and trace element analyses were performed on 75 stillborn calves from the same dairy cow herd. The elements Fe, Mn, Zn and Cu were measured in the livers of 66 of the calves. The calves ranged in age from 259 to 299 days of gestation, and in weight from 18 to 58 kg. Based on the quotients of organ and other body parts, stage of growth of the humerus and age, the animals were grouped as either preterm (P), term but light (TL), and term with appropriate weight (TA) calves. In P group calves the heart, lungs, liver, kidneys, thymus, spleen and thyroid glands were relatively heavy. In the TL group calves the brain, heart, lungs and thyroid glands were relatively heavy whereas the spleen and thymus were comparatively light. The liver Fe and Zn values were lower in this group than in the other 2 groups.

[Birth weight and measurements of various body parts of stillborn calves of a large dairy cattle herd]. / Geburtsmassen und Masse einiger Körperteile totgeborener Kälber einer grossen Milchrindherde.

Stillborn calves (80 animals) originating from one dairy herd were used for studies on allometric measures in newborn calves. In the first approach some factors were neglected and only the effect of the calves' sex was considered. Differences in mean birthweight between male and female calves were reflected in organ and other body constituent weights too, but with different relations between them. Enlarged thyroid glands could be observed in both sexes but more often in female calves meaning that there is no correlation between thyroid size and body weight. Strong correlations of bones, muscles and outer body measures and looser ones of internal organs (thymus, liver, lung, kidneys, spleen) and endocrine glands (adrenal glands) with body weight were found especially in male calves. In some calves the sometimes enlarged liver looked like a fatty liver with its pale yellowish appearance and crumbly consistency.

[Birth injuries in calves and perinatal calf losses in a large dairy herd]. / Geburtsschäden an Kälbern und perinatale Kälberverluste in einer grossen Milchrindherde.

Post-mortem examinations were carried out on 65 calves which were stillborn or died within 24 hours of birth. All calves came from a large dairy unit with about one thousand cattle of the Schwarzbuntes Milchrind breed. To evaluate the perinatal losses, the farm records of parturitions from 1985-1990 were used. The calves had gross damage of the CNS, the musculature, subcutaneous tissue and internal organs such as lung and intestines. It may be assumed that a lesser degree of similar damage would also be present in the surviving calves. The level of perinatal losses is determined particularly by deaths following prolonged parturition due to foetal oversize in heifers and young cows, but also by the birth of immature calves of low weight after pregnancy of normal or decreased duration and by twin pregnancies with high total calf mass and relative immaturity of the calves.

[Oral and intramuscular ferric dextran administration in male rearing calves. 5. Live weight gain during maintenance in fluid feed and weaning ranges]. / Zur oralen und intramuskulären Ferridextranintervention bei männlichen Aufzuchtkälbern. 5. Mitteilung. Lebendmassezuwachs während der Haltung im Tränk- und Absetzkälberbereich.

195 rearing calves, which immediately after their gathering from various dairy farms had an anaemia frequency of 57.4% and an average age of 22 d and an average live weight of 43 kg, were at random divided into 3 groups and received in addition to the iron in the rations oral (B), intramuscular (C) or no (A) ferridextrane applications during their 56-day stay in the fluid feed range of a rearing farm. The average live weight gain of the calves during these 56 days in groups A, B, and C was 882 +/- 171, 949 +/- 145 and 912 +/- 170 g/d resp. and during the 57-day stay in the weaning range 664 +/- 205, 715 +/- 222 and 670 +/- 226 g/d resp. The significant advantage in the development reached by the calves in group B over those in group A during their stay in the fluid feed range did not get lost after the change to the weaning range. Based on the cost of medicine and on the development of the live weight of the calves in the 3 test groups in the fluid feed and weaning ranges the economic effect of ferridextrane applications was calculated. Under the rearing conditions given, iron intervention proved to be sensible for both health and economic reasons.

[Oral and intramuscular ferridextran intervention in growing male calves. 1. Hematologic reactions]. / Zur oralen und intramuskulären Ferridextranintervention bei männlichen Aufzuchtkälbern. 1. Mitteilung. Hämatologische Reaktionen.

195 calves were at random divided into 3 test groups and received oral (200 mg Fe/d) or intramuscular (1.0 and 1.5 g Fe on the 3rd and 36th day of the period of fluid feeding) applications of ferridextrane or no additional quotas of iron (control group) and a limited supply of milk replacer and skim milk as well as ad libitum supply with concentrated feed and dried green fodder during their 56-day period in the range of the rearing farm where the calves receive fluid feed. Iron intervention was carried out without considering the individual iron content of tissue. Its effect was evaluated according to the hemoglobin content (Hb), the hematocrit (Hc) and the mean corpuscular hemoglobin concentration (MCHC) in venous puncture blood. There was no difference between the test groups as to the stabling conditions (affiliation to race and genotype, birth weight, age and live weight resp. at the beginning of the experiment, live weight gain before the beginning of the experiment). In the control group Hb, Hc and MCHC were analogous to previous epidemiologic investigations concerning the anaemia of calves. The ferridextrane interventions carried out resulted in a raised level of Hb and Hc and diminished anaemia frequency as well as the shortened duration of anaemia in this rearing period.

[Reference values of hemoglobin content, hematocrit and mean concentration of corpuscular hemoglobin of calves reared without iron supplementation. 3. Comparison of the observed age dependency with literature values]. / Referenzwerte des Hämoglobingehalts, des Hämatokrits und der mittleren korpuskulären Hämoglobinkonzentration bei Aufzuchtkälbern ohne Eisensubstitution.

The average hemoglobin (Hb) and hematocrit (Hc) values determined in our own investigations with 491 rearing calves in the first five months of their lives were compared with the nationally and internationally published data of the dependence of these hematologic values on the age or rearing resp. milk fattening calves. The main influencing factors on the ageing development were the initial level of Hb and Hc, the length of the milk feeding period, the time of the beginning of feed supplementing, the development of dry matter consumption resp. the supply with milk, the iron content of the milk exchanger and the live weight increase achieved under the respective nutritional conditions. This dependence on the development proves that anaemia occurring with rearing calves in the first few weeks of their lives is mainly caused by iron deficiency. From the similarity of the average Hb resp. Hc values one can derive the conclusion that the considerable anaemia frequencies observed in one's investigations are not a phenomenon specific of one farm or of time but represent a general problem of the rearing of calves without iron substitution.

[Reference values of hemoglobin content, the hematocrit and mean concentration of corpuscular hemoglobin in rearing calves without iron substitution. 2. Dependence on live weight and age]. / Referenzwerte des Hämoglobingehalts, des Hämatokrits und der mittleren korpuskulären Hämoglobinkonzentration bei Aufzuchtkälbern ohne Eisensubstitution.

The hamoglobin content (Hb), the hematocrit (Hc) resp. the mean corpuscular hemoglobin concentration (MCHC) were determined resp. calculated of the blood samples (1 to 6 per animal) taken from 491 rearing calves during the first 23 weeks of their lives. Hb, Hc and MCHC were graphed as arithmetic means with standard deviation, as quartiles and as frequency distributions on an interval scale in dependence on live weight (20 ... 160 kg) resp. age (1 ... 161 days). It follows that the period of development from birth up to 28 days of keeping in the weaning area of the rearing farm, up to an age of 63 days resp. a live weight of 80 kg must, under the reference conditions, be considered the minimal period in which the supply of iron covering the needs by iron intervention in the whole stock of calves seems advisable.

[The reference values of the hemoglobin content, the hematocrit and the mean concentration of corpuscular hemoglobin of calves reared without iron substitution. 1. Dependence on the rearing period]. / Referenzwerte des Hämoglobingehalts, des Hämatokrits und der mittleren korpuskulären Hämoglobinkonzentration bei Aufzuchtkälbern ohne Eisensubstitution. 1. Mitteilung. Abhängigkeit vom Haltungsbereich.

A total of 1.088 blood samples (1 to 6 per animal) were taken from 491 rearing calves in the colostral period, the milk feeding period and the weaning period (at the age of 4, 22, 51, 79, 105, 122 and 145 days); the hemoglobin content (Hb), the hematocrit (Hc) resp. the mean corpuscular hemoglobin concentration (MCHC) were determined resp. calculated. Hb, Hc and MCHC were drawn in diagrams in dependence on the rearing period as arithmetic means with standard deviations, as quartiles and as frequency distributions on an interval scale. During the rearing periods with milk feeding the anaemic frequency was considerable. Anaemia resp. hypochromia frequency had an inverse relation to the developing increase of concentrated feed and roughage consumption and thus makes it probable that the cause of anaemia is the intake and/or absorption of iron insufficient for the weight gain performance achieved. The consumption of solid feed by the hematologically examined calves developed more quickly than in other GDR rearing farms due to the early ad libitum supply with this feed component and the composition of fluid feed with milk. Reference is made that the frequency of hypoferric anaemia can also be considerable during the milk feeding period in the intensive rearing of lambs and kids if an effective iron intervention is not made.

[Investigations of anemia of male rearing calves. 4. Relations between weight at birth, duration of keeping and increase of the ive weight in the period of the calves being fed on colostrum as well as the count erythrocytes in the weaning period of the calves]. / Untersuchungen zur Anämie bei männlichen Aufzuchtkälbern. 4. Mitteilung. Abhängigkeiten zwischen Geburtsmasse, Haltungsdauer und Lebendmassezuwachs im Kolostralkälberbereich sowie rotem Blutbild im Tränkkälberbereich.

With 195 male rearing calves which received concentrates ad libitum beside fluid feed with milk from their 5th day of life onward, investigations were made if and how far the characteristics of the development of the calves while they are fed on colostrum (body weight at birth, live weight increase and duration of keeping or stalling age) correlate with the hemoglobin content (Hb), the hematocrit (Hc) and the average corpuscular hemoglobin concentration (MCHC) of the animals on the 3rd, 28th resp. 56th day of keeping in the weaning period. There was a significant simple dependence particularly between body weight at birth, live weight increase and stalling age on the one hand and the hematologic values on the 3rd day of keeping in the weaning period on the other. A partial correlation analysis showed that the live weight increase while the calves were fed on colostrum was the main variable for all three hematologic parameters at the beginning of the weaning period of the calves. With increasing live weight, Hb, Hc and MCHC were diminished. This analysis was supplemented by the results of a cross--section investigation of the development of the milk and concentrate consumption and the Fe-intake of the calves fed on colostrum. The calculation of the Fe-balance showed that the mere ad libitum supply with feed supplements rich in Fe cannot prevent Fe-deficiency. Anaemia developing in the first month of the calves' lives is not a physiologic one but essentially caused by Fe-deficiency.

[Normal values for the hemoglobin content, hematocrit and the average corpuscular hemoglobin concentration in calves for rearing: fall study, 1976]. / Normwerte des Hämoglobingehalts, des Hämatokrits und der mittleren korpuskulären Hämoglobinkonzentration bei Aufzuchtkälbern--Herbststudie 1976.

Raised calves were analysed for their frequency distributions of haemoglobin, haematocrit, and mean corpuscular haemoglobin concentration, depending on phases of keeping, in two cross-section (n = 146 and 196) and one longitudinal section studies (the latter on three dates, n = 149, 144, and 141). Race, birth weight, age, and live weight of the calves and their fathers as well as lactation age of their mothers were used for reference. All animal groups exhibited at any time of testing significant deviations from Gauss' distribution in all tests undertaken to verify the normality of frequency distributions of the above haematological variables. Those frequency distributions exhibited clearly visible variations, depending on phases of keeping. A concept to meet such conditions is proposed for evaluation of all variables of the red blood count.

[Anemia of male rearing calves. Connections between anemia and feed consumption, development of the live weight and disease development]. / Untersuchungen zur Anämie bei männlichen Aufzuchtkälbern. 3. Mitteilung: Zusammenhänge zwischen Anämie sowie Futterverzehr, Lebendmasseentwicklung und Erkrankungsgeschehen.

Calves in a longitudinal investigation over the first rearing period in a rearing farm were grouped according to their anaemic status under consideration of the degree of severity and the duration on the basis of the hemoglobin contents resp. the hematocrit values on the 3rd, 28th and 56th rearing day. There were significant differences between the groups of calves with differing anaemia status concerning the absolute and relative feed consumption (milk, concentrated feed, hay resp. iron), the development of the live weight as well as the frequency of the treatment against pneumonia and/or diarrhoea.

[Anemia of male rearing calves. 2. Duration of anemia]. / Untersuchungen zur Anämie bei männlichen Aufzuchtkälbern.

From 203 male rearing calves in a longitudinal study during the first rearing period in a rearing farm the time could be determined in which the hemoglobin quota, the hematocrit resp. the average corpuscular hemoglobin concentration were lower than 10,5 g/dl, 33% resp. 30.5 g Hb/dl erythrocytes. The average duration of anaemia was 45, 29.5 resp. 44 days of the total of 56 keeping days in this rearing range (80.4%, 52.7% resp. 78.6% of the keeping period). During this rearing period 89.2%, 71.4% resp. 90.6% of all animals were anaemic for a shorter or longer time. With 29.8%, 26.2% resp. 29.9% of the anaemic calves the anaemic phase exceeded 56 days.

[Investigations of anemia of male rearing calves. 1. Reference conditions and anemia frequency]. / Untersuchungen zur Anämie bei männlichen Aufzuchtkälbern. 1. Mitteilung: Referenzbedingungen und Anämiefrequenz.

In a longitudinal investigation (3 points of time n = 214, 206 resp. 202) the hemoglobin quota (Hb), the hematocrit (Hct) resp. the average corpuscular hemoglobin concentration (MCHC) were analysed at male calves receiving semi-liquid feed in the transitional period from pre-ruminal to ruminal digestion (56d). Breed, live weight development, consumption of milk, concentrated feed resp. dried forage, diseases of the calves as well as the father and the milk yield resp. the lactation age of the mother were registered as reference conditions. The percentage of calves with an Hb less than 10.5 g/dl was at the three points of time 50.00%, 86.41% resp. 41.58%, of calves with an Hct less than 33,5% it was 43.46%, 66.02% resp. 31.68% and of calves with an MCHC less than 30.5 g Hg/dl erythrocytes 51.87%, 76,21 resp. 47,03%. 21.50%, 33.50% resp. 4.46% of all test animals even had an Hb of less than 8.5 g/dl.