Serological examination and egg production of progeny of fowl experimentally infected with egg drop syndrome 1976 virus

Following EDS'76 virus (BC14 virus) infection of breeder chickens by the conjunctival route, vertical transmission occurred in the first week after infection. In the progeny which had been infected with EDS'76 virus by the vertical route, increasing haemagglutination inhibiting (HI) titres to BC14 virus and increasing numbers of birds with HI titres were observed from 3 weeks to 15 weeks of age. Sixty-one per cent of the hens and 77 per cent of the cocks had 2 log HI BC14 virus titres exceeding 4 at an age of 15 weeks. Some birds which han been serologically negative throughout the rearing period, seroconverted between 25 and 28 weeks of age. This phenomenon occurred in hens as well as in cocks. Simulation of stress twice during the laying period by injection of corticosteroid hormone did not increase the number of birds serologically positive to EDS'76 virus. EDS'76 was observed in the group of hens that was vertically infected, since egg production was significantly depressed between 28 and 34 weeks of age. Probably this was mainly the results of a production drop in the hens showing serconversion at 27 or 28 weeks of age. In this group of fowl vertically infected with EDs'76 virus, serologically positive birds appeared to be protected for the greater part to BC14 virus challenge at 50 weeks of age, while negative birds seemed to be fully susceptible. Chicks hatched from eggs collected in the third and fourth week after infection of the dams had maternal antibodies. Fertility and hatchability of apparently normally shelled eggs seemed not to be affected after BC14 virus infection of the dams. Intensive contact with contaminated faeces is probably an indispensable condition for lateral transmission of the virus.     

Effects of experimental infection of fowl with EDS'76 virus,infectious bronchitis virus and/or fowl adenovirus on laying performance

Following BCI4 (EDS'76) virus infection of brown layer hens at 33 weeks of age, production of normally shelled eggs dropped from 87 per cent to 49 per cent within 3 weeks. The production of soft shelled and shell‐less eggs attained a maximum of 33 per cent 3 weeks after infection (p.i.). Shell quality recovered completely within 5 weeks p.i.

Egg production problems in White Leghorns infected with BCI4 virus were less severe and of shorter duration than in brown layers.

Both in brown layers and in White Leghorns total egg production, mean weight of normally shelled eggs, and internal egg quality were not affected following BCI 4 virus infection at 33 and 28 weeks of age, respectively. Besides shell abnormalities no clinical disease symptoms were observed. Vaccination with a commercial EDS'76 vaccine (Nobivac EDS'76^®) at 17 weeks of age had no adverse effects on laying performance and provoked adequate immunity against challenge at 33 weeks of age. The same observations were made following BCI4 virus infection at 17 weeks of age.

After infectious bronchitis virus (IBV) (H52 virus) infection of laying fowl the percentage of eggs with shell aberrations (rough, misshapen and/ or soft shells) increased to a maximum of 8 per cent, total egg production was depressed, mean egg weight was reduced I to 2 grams, and up to 10 Per cent of normally shelled eggs showed watery, not ropy thin albumen. This abnormally thin albumen was observed in a considerably higher proportion of eggs with shell defects than in normally shelled eggs. No turbidity of the thick albumen was observed and no symptoms of respiratory disease were noticed.

The severity and duration of adverse effects of IBV infection on laying performance depend very much on the stage of production in which the infection occurs. Following IBV infection at the onset of production a much severer drop in total production and in production of normally shelled eggs, a greater increase in the number of abnormally shelled eggs, and more lasting adverse effects on egg weight and internal egg quality were observed, in comparison with infection after peak production. Compared with single infections, a combined BC14 virus and IBV infection of brown layers at 33 weeks of age resulted in greatly potentiated adverse effects on total egg production, number of eggs with aberrant internal quality, and duration of production problems.

Following a combined BC14 virus and IBV infection, in a great proportion of eggs with shell defects and watery thin albumen, turbidity of the thick albumen was observed also, probably due to combined effects on the uterus of both IBV and BC14 virus.

BC14 virus infection did not reinforce the adverse influence of IBV infection on egg weight.

The same observations as described for the combined BC14 virus and IBV infection were made following BC14 virus infection of fowl previously infected with IBV.

It is concluded that changes of internal egg quality in field cases of EDS'76 are most likely due to subclinical IBV infections.

After infection of brown layers at 33 weeks of age with fowl adenovirus 66 (FA V 66) neither symptoms of clinical disease were observed nor effects on egg production, egg weight, and egg quality. Also, in a combined infection with FA V66, IBV, and BCI4 virus, no pathogenic significance could be attributed to the FAV.     

Egg transmission of egg drop syndrome 1976 virus in fowl

Summary

Egg transmission of egg drop syndrome 1976 virus (BC14 virus) in fowl was demonstrated in the second and third week after experimental infection. Eggs of BC14 virus infected hens were incubated weekly after disinfection with formaline gas. After 18 days of incubation, eggs with live embryos were homogenized. This egg material was fed to adult hens, housed in isolators.

Seroconversion in these birds demonstrated egg transmission.

It is suggested that egg transmission occurs as a result of viremia.     

Egg transmission of egg drop syndrome 1976 virus in fowl

Summary Egg transmission of egg drop syndrome 1976 virus (BC14 virus) in fowl was demonstrated in the second and third week after experimental infection. Eggs of BC14 virus infected hens were incubated weekly after disinfection with formaline gas. After 18 days of incubation, eggs with live embryos were homogenized. This egg material was fed to adult hens, housed in isolators. Seroconversion in these birds demonstrated egg transmission. It is suggested that egg transmission occurs as a result of viremia.     

Contribution to the aetiology of synovitis in chickens,with special reference to non‐infective factors. V

Summary

A comparative study was undertaken regarding the extractability of glucosaminoglycans and mucoproteins in the tendon tissue of birds highly susceptible to synovitis, viz. broiler breed cocks (BB cocks), and of birds highly resistant to synovitis, viz. White Leghorn hens (WL hens).

It .was shown that in the case of WL hens this extractability decreased in accordance with ageing. In the case of BB cocks such a decrease was not observed. This observation is in support of a working hypothesis which supposes a relatively high degree of interaction between the several components of tendon tissue (e.g. collagen and glucosaminoglycans/mucoproteins) in the case of WL hens, and a relatively low degree of this interaction in the case of BB cocks.

Moreover the results of this study account for the observation that the tendon tissue of WL hens is more resistant to tensile stress than that of BB cocks, and they indicate that the above interaction is a determinant in the aetiology of synovitis.     

Effects of infectious bronchitis virus (Arkansas strain) on laying chickens

Seventy-seven-week-old white leghorn layers were inoculated intraocularly with the Arkansas strain of infectious bronchitis virus (AIBV) to study the effects of the virus on egg production and on antibody response of the birds. Infected hens laid fewer eggs than the controls, and those eggs weighed less than eggs laid by controls. Further, the shell quality and internal quality of eggs laid by infected birds were inferior. The serum hemagglutination-inhibition (HI) titers of infected birds increased continuously through 4 weeks postinfection; serum HI titers of the controls were negligible.     

Resistance of chickens to challenge with the virulent Herts 33 strain of Newcastle disease virus induced by prior infection with serologically distinct avian paramyxoviruses.

Results indicate that some degree of protection from challenge by Newcastle disease virus (NDV)/Herts 33 was conferred on chickens by prior infection with PMV/turkey/Wisconsin/68, PMV/turkey/Ontario/6661/68, PMV/Netherlands/449/75 and PMV/parakeet/England/39/78 viruses, all of which are serologically related but distinguishable from NDV. Except for one bird which survived challenge three weeks after infection with Robin/Hiddensee/19/75, no protection was seen in chickens infected with other unrelated avian paramyxoviruses. In contrast to infection with NDV-B1, birds protected by infection with avian paramyxoviruses showed large increases in NDV haemagglutination inhibition (HI) titres after challenge. In these birds considerable increases in the homologous HI titres were also seen after challenge.     

Involvement of spleen components of mature fowl in the primary and secondary humoral antibody response following experimental EDS'76 virus infection

Summary

Cellular changes in spleens of mature fowl in relation to both the primary and secondary humoral antibody response following experimentalEDS'76 virus infection were studied. The influence of splenectomy on humoral antibody response was also examined.

Experimental fowl had been naturally infected with fowl adenovirus (FAV) but did not possess precipitins to these viruses at the time of EDS’ 76 virus infection. Since EDS'76 infection provokes a recall of the group antibody to FAV, this infection simultaneously induces a primary response against EDS’ 76 virus and a secondary response due to the recall of the group antibody to FAV.

HI and precipitating antibodies toEDS'76 virus (primary response) werefirst detected at 6 and 8 days p.i. respectively. Curves of HI, precipating and neutralising antibody titres were biphasic; the first peak (IgM peak) occurred at 10–11 days p.i., the second (IgG peak) at 16–28 days p.i.

Precipitating antibodies to FAV (secondary response) were demonstrated from 4 days p.i. The curve of these antibody titres was also biphasic, with peaks at the same times as in the primary response.

Based on HI and AGP testing of primary and secondary immune response in both splenectomised and non‐splenectomised fowl it is concluded that in the primary response the spleen of the adult fowl is involved significantly in only IgM secretion, while in the secondary response it is likely that bothIgM and IgG are secreted in considerable amounts.

Clusters of lymphoblasts and plasmablasts were observed at 3 days p.i. in the red pulp. It is very likely that antigen‐antibody complexes are formed from that time and circulate bound to the surface of lymphocytes. These antigen‐loaded lymphocytes are ‘picked up’ from the blood stream by

– red pulp macrophages, leading to enhanced formation of lymphoblasts in the red pulp. Great numbers of these cells (which are very probably IgM secreting cells) were present on days 6 and 7 p.i., but were no longer detectable after day 10 p.i.

– macrophages of the macrophagalellipsoidal corona (MEC), leading to significant enlargement of the periellipsoidal lymphoid tissue(PELT) by an increase of the number of lymphocytes observedfrom days 4–12 p.i. The MEC was significantly enlarged from 7–12 days p.i., very likely due to an increased number of macrophages.

Following deposition of antigen in the white pulp, formation of follicles begins. The number of small, intact follicles includingfollicle precursors increasedfrom 6 days p.i. From 15 days p.i. to the end of the experiment both the number and size of follicles increased significantly.

Uptake and processing of antigen by macrophages is probably accompanied by death of some of these cells. This might explain the degenerative changes observed in large mesenchymal cells, probably macrophages, at 3 and 5 days p.i. in the red pulp and at 5 and 6 days especially in the MEC. Splenitis which was present at 3 and 5 days p.i. and oedema observed in and around ellipsoidal cells at 5 days p.i. may be due to mediators released from these degenerative macrophages.

A significantly increased number of follicles with lymphoblasts was seen from 2–15 days p.i. while lymphoblasts and plasmablasts were present in the PELT from 5–15 days p.i., but predominantly at 6 and 7 days p.i. It is likely that disruption of follicles and blast transformation of white pulp lymphoid cells are secondary response events. White pulp lymphoblastsand plasmablastsare probably IgG secreting cells.

Splenomegaly was observed at 3, 5 and 6 days after infection and was mainly due to swelling of red pulp macrophages and infiltration of granulocytes in the red pulp. Ellipsoidal and periellipsoidal changes could contribute to the splenomegaly at 5 and 6 days p.i.     

Spread of Bovine Virus Diarrhoea virus in a herd of heifer calves

Summary

A calf persistently infected and immunotolerant to Bovine Virus Diarrhoea virus (BVD virus) was, on purpose, introduced to a herd of heifer calves over 4 months of age that had been reared as recipients for embryo transplantation.

All calves were brought in contact with the persistently infected animal. In total, 240 calves were involved in this experiment, 22 of which were serologically negative when introduced. These serologically negative animals developed antibodies against BVD virus within 5 months after introduction. At short distances from the persistently infected BVD virus shedder, negative calves seroconverted within 2 months, but at greater distances the moment of seroconversion was unpredictable.

The calves that had undergone a natural infection with BVD virus received embryos after transportation to an allied farm. In total, 14 calves were born after embryo transplantation, all of which were free of BVD virus, in spite of the presence of BVD‐virus on the latter farm.     

Differences in stride between healthy ostriches (Struthio camelus) and those affected by tibiotarsal rotation

Twenty healthy ostriches (ten cocks and ten hens), and twenty birds with tibiotarsal rotation (nine cocks and 11 hens) (14 months old) were isolated, hooded and weighed. A run (50 m x 2.5 m) was divided into sections marked 5 m, 10 m, 15 m and 20 m. Time taken for each bird to pass these points was recorded and speed computed. The degree of tibiotarsal rotation in the right foot was mean +/- SEM, 156 +/- 2.69 degrees. Comparisons between left and right foot length in healthy birds showed no significant differences. Foot length was significantly lower in tibiotarsal rotation (P = 0.03). The right foot in tibiotarsal rotation was significantly shorter than the left foot. The number of strides per each 5 m division were significantly (P < 0.05) greater in tibiotarsal rotation by comparison with healthy birds. At 20 m, healthy cocks had more strides than hens. The stride length in hens was significantly (P < 0.05) greater than cocks at 5, 10 and 15 m, respectively, but lower throughout in tibiotarsal rotation (P = 0.001). The speed of hens was significantly (P < 0.05) greater than cocks. Tibiotarsal rotation resulted in significantly (P < 0.05) reduced speeds. Hens may be able to escape danger faster than cocks. The occurrence of tibiotarsal rotation necessitates consideration of genetics, management, sex, nutrition and growth rates.     

Seroprevalence of egg drop syndrome - 76 virus as cause of poor egg productivity of poultry in Nsukka,South East Nigeria

To determine if egg drop syndrome 76 virus infection is among the causes of lowered egg productivity in commercial poultry farms in South Eastern Part of Nigeria and to know the prevalence of the infection, ten farms with history of lowered egg production in Nsukka local government area of Enugu State were randomly selected. Sera from ten hens in each of the selected farms were assayed for antibodies against EDS 76 virus by the haemagglutination-inhibition (HI) test. The mean HI titre of the ten hens in each of the farms was recorded as EDS - 76 antibody titre for the farm. Nine out of the 10 farms tested were positive for EDS - 76 antibodies with HI titres ranging between 16 and 256. Out of 10 flocks with production of 65% and above 9 were EDS-76 HI negative.     

Outbreaks of egg-drop syndrome-1976 in Japan and its etiological agent

A condition similar to egg-drop syndrome-1976 (EDS-76) occurred in 14 broiler breeding flocks in 2 farms in Japan from December 1978 to January 1980, and it was diagnosed as EDS-76 by serologic and virological investigations. Egg production fell suddenly when the hens were 30 to 55 weeks of age, and the depression lasted 3 to 7 weeks. Production fell 6 to 25%. Depressed egg production was accompanied by the laying of shell-less, soft-shelled, and thin-shelled eggs associated with loss of egg-shell pigment. Eleven isolates of hemagglutinating adenovirus were isolated from cloacal swabs (10 isolates) and a uterus (1 isolate) of hens in one farm. One isolate, cloned and named JPA-1, had the same antigenicity in serologic tests and the same biological and physicochemical properties as the BC14 strain of EDS-76 virus.     

Experimental infection of laying chickens with egg-drop syndrome 1976 virus

Brown layer hens (BC and HC strains) and white layer hens (WL strain) orally infected with the H-162 strain of the egg-drop syndrome 1976 virus developed few clinical signs except for abnormal egg production. Depressed and/or aberrant-egg production was observed for 3 days or longer in 17 of 18 BC hens, 13 of 15 HC hens, and 10 of 17 WL hens. On the average, abnormal egg production began 8.8, 10.3, and 12.2 days after infection of the BC, HC, and WL hens, respectively. Egg production was depressed in the WL hens, but little depression was observed in the BC and HC hens. Aberrant-egg production was much less frequent in the WL hens than in the BC and HC hens. Aberrant eggs were shell-less, soft-shelled, thin-shelled, and/or discolored. No eggs of abnormal internal quality or shape were observed. The virus spread from infected BC and WL hens to contact hens.     

Biochemical changes in blood and uterine fluid of fowl following experimental EDS'76 virus infection

The pH, pCO2, and pO2 values and the concentrations of sodium, potassium, calcium, magnesium, chloride, phosphorus, bicarbonate, base excess, protein, glucose, as well as the activity of alkaline phosphatase and malate dehydrogenase were determined in the venous blood and uterine fluid of control and EDS'76 virus-infected fowl. Moreover, the pH of the mucosa of different parts of the oviduct was measured. Hens were examined in the period from 10 to 24 days following infection; blood and uterine fluid samples were collected approximately 14 hours after oviposition, provided a plumped egg was present in the uterus. Examination of blood and pH measurement of oviduct mucosa did not yield significant differences between infected and noninfected hens. In comparison with noninfected control birds, the mean sodium concentration of the uterine fluid of infected hens producing soft shelled or shell-less eggs had evidently increased, while the mean concentration of potassium, calcium, magnesium and glucose had decreased. Similar differences were also observed between infected hens producing normally shelled eggs and infected hens producing abnormally shelled eggs. No significant differences between infected and not infected hens were observed concerning the other values determined in the uterine fluid. It is concluded that functional disturbances which account for shell aberrations following EDS'76 virus infection are located in the surface epithelial cells of the uterine mucosa. These disturbances are very probably initiated by a depressed function of the sodium pump. All changes observed in the uterine fluid of infected hens could be explained by this depressed function.     

The growth of abdominal adipose tissue in various production-type of domestic fowl

At hatching, the abdominal fatty tissue is less developed than the subcutaneous fatty tissue. However, it grows more intensively during the post-incubation period through both the hyperplasia and hypertrophy of the fat cells. In the cocks, hyperplasia reaches its peak at the age of 9 weeks, followed by a decrease; then hyperplasia continues until the age of 25 weeks. In the hens the peak of hyperplasia comes later, at the age of 14 weeks; then it decreases until the age of 25 weeks is reached. Hyperplasia and hypertrophy are more pronounced in the early period and are somewhat higher in the cocks. During the period of sexual maturation both processes are more intensive in the hens; owing to them, the total weight of the abdominal fatty tissue of hens increases both absolutely and relatively in comparison with the cocks. The cellularity of the first population of adipocytes is assumed to culminate at the age of three to five weeks. Then follows the cellularity of the second population which persists throughout sexual maturation. The pictures of hyperplasia and hypertrophy are qualitatively the same in different production types of fowl, but the size is twice as large in the broiler type than in the laying type of fowl.     

The development and growth of subcutaneous adipose tissue in various production types of domestic fowl

Hyperplasia and hypertrophy of fat cells of the subcutaneous adipose tissue were studied in different production types of fowl in the post-incubation period. The cocks and hens of laying type were found to have fewer and smaller fat cells than the birds of broiler type. The highest hyperplasia was recorded in the first nine weeks of age, then followed a decrease, lasting until the 25th week. Hypertrophy continued step by step throughout the period of study and increased when hyperplasia decreased. The differences between sexes increase during sexual maturation: in the hens the hypertrophy of cells increases and hyperplasia does not decrease so quickly as in the cocks. Before sexual maturity, hypertrophy as well as hyperplasia are somewhat higher in the cocks.     

Comparison of serological tests for the measurement of the primary immune response to avian infectious bronchitis virus vaccines

The immune response of individual chickens exposed in an aerosol apparatus to live commercial avian infectious bronchitis virus (IBV) vaccines was measured by serum neutralization (SN), haemagglutination inhibition (HI), complement fixation (CF) and agar gel precipitin (AGP) tests over a period of 14 weeks.The SN titres showed considerable variation for individual chickens and in a large number of birds were negative until 14 weeks after infection.Positive HI titres were recorded for most birds at one week after infection and persisted throughout the observation period. Some relationship was seen between HI and SN titres particularly in birds showing a high immune response.The results obtained with the AGP were transient, variable and did not compare well with results obtained by the other tests. The highest number of positive AGP reactors were seen two to three weeks after infection.Most birds showed positive titres by the CF test at some time after infection but titres were always low and did not correlate with results obtained by the other tests.Twenty-two weeks after vaccination 23 chickens were challenged by aerosol exposure to the Massachusetts 41 strain of IBV and four days later the trachea, kidneys and oviducts were removed from each bird for attempted virus isolation. Virus was recovered from only one kidney and 11 trachea samples. The mean pre-challenge HI and SN titres of birds from which no virus was recovered were significantly higher than the mash titres of vaccinated birds from which virus was isolated after challenge.     

Microbiological and histopathological effects of an induced-molt fasting procedure on a Salmonella enteritidis infection in chickens.

A study was undertaken to determine if a 2-week feed-removal protocol, as is used by industry to induce a molt in aging hens, would affect the course of a Salmonella enteritidis infection. White leghorn hens aged 69-84 weeks were deprived of feed to induce a molt, and on day 4 of the fast, the birds were orally infected with 5 x 10(6) S. enteritidis. S. enteritidis organisms were enumerated in the spleen on day 6 and from the alimentary tract on days 7, 14, 21, 28, and 35. Little difference was detected in numbers of S. enteritidis from spleens of molted and unmolted hens. Significantly more molted hens shed detectable intestinal S. enteritidis than unmolted hens on day 14 (one of two trials) and day 21 (one of two trials). Intestinal levels of S. enteritidis were increased 100- to 1000-fold in the molted birds on day 7 (one of two trials) and day 14 (two of two trials), and many of the hens exhibited bloody alimentary secretions. Histological examination of the intestinal tract of S. enteritidis-infected molted hens showed increased inflammation in the epithelium and lamina propria of colons and ceca, compared with unmolted infected hens.     

Egg production in relation to the results of a long term serological survey of 73 flocks of fowl

Summary

Seventy‐three flocks of fowl were tested at regular intervals for the presence of precipitins to fowl adenovirus (AV) and infectious bronchitis virus (IBV), haem‐agglutinating inhibiting antibodies to BC14 virus, and of agglutinins to Mycoplasma gallisepticum (M.g.) and Mycoplasma synoviae (M.s.). In all the eight flocks affected with Egg Drop Syndrome (EDS ‘76), egg production problems were associated with increasing numbers of BCI4 virus reactors and AV reactors. In flocks showing production problems other than EDS ‘76 without any apparent cause, the average percentage of AV reactors increased significantly after the rearing period; this was not true of IBV reactors. BC14 reactors were either absent or present only once, in small numbers and with low titres, during the test period. The average percentage of AV reactors did not increase after the rearing period either in normally producing flocks or in flocks with production problems for which other diseases or dietary errors plausibly accounted for these problems. All this suggests a pathogenic role of AV in production problems. One can conclude from the high percentage of reactors in all groups of flocks that sub‐clinical IBV infections are common.

The percentage of IBV reactors during the laying period of flocks with EDS ‘76 was significantly higher than that of normally producing flocks. It is therefore suggested that subclinical IBV infection could be among the factors causing stress, acting as a trigger for EDS ‘76.

All M.g.‐infected flocks showed production problems; M.s. infections could not be related to egg production disturbances.     

Isolation of avian infectious bronchitis virus from experimentally infected chickens.

Virus was recovered from the faeces of chickens infected at three or four weeks of age for more than 20 weeks after infection with commercial vaccines or with the T strain of avian infectious bronchitis virus (IBV). Virus was not recovered from the trachea, liver, spleen, bursa or kidneys of T strain infected birds longer than 29 days after infection at which point IBV was recovered from the bursa of a single infected bird. In a subsequent experiment IBV was recovered from the caecal lymph nodes and faeces of one of five birds 14 weeks after infection with a commercial vaccine but no virus was isolated from the trachea, kidneys, duodenum, bursa, ovaries or testes of any of the five birds at this time.