共查询到20条相似文献，搜索用时 15 毫秒
1.
Commercially-reared laying chickens were challenged at 31 weeks of age with a virulent infectious bronchitis (IB) virus. They showed a sharp drop in egg production, despite having been vaccinated at four and eight weeks old with live attenuated IB vaccines to a recommended schedule. In contrast, similar birds that had been further immunised at point-of-lay with inactivated oil emulsion IB vaccine, or with a combined IB/Newcastle disease (ND) emulsion vaccine, showed no detectable fall in egg production after the same challenge. Unvaccinated susceptible specific pathogen-free birds challenged at the same time stopped laying almost completely. In the birds revaccinated with emulsion vaccine, measurement of haemagglutination inhibition antibody levels to IB showed their geometric mean titres to be raised from less than 5 log2 at the time of vaccination to over 10 log2 four weeks later. Their antibody levels did not rise further followining the IB challenge whereas in the birds that had not been revaccinated antibody rises to nearly 10 log2 were detected after the same challenge. For pullets vaccinated earlier with live IB vaccine, revaccination with inactivated IB or IB/ND oil emulsion vaccine at point-of-lay provides a safe and effective way of protecting their egg production against IB infection. 相似文献
2.
Three groups of chicks were vaccinated by aerosol, intra-ocular and drinking water routes with a live infectious bronchitis (IB) vaccine. At one, two, six, 15 and 32 weeks after vaccination five birds from each group were sampled for testing for IB haemagglutination-inhibiting (HI) antibodies and challenged. Assessment of susceptibility to infection was measured by recovery of virus from individual tracheas and from kidney and gonad pools four days after challenge. Virus was isolated from all kidney and gonad pools of birds challenged one week after vaccination, the kidney and gonad pools of the drinking water vaccinates at two weeks, the kidney pool of the intra-ocular group at 15 weeks and all organ pools except the gonads of the intra-ocular group at 32 weeks. Tracheal resistance was found in most of the birds challenged one week after vaccination and in all the birds tested at two weeks but had begun to wane by six weeks after vaccination. No correlation was found between low HI antibody titres of individual birds and their susceptibility to challenge measured by reisolation of virus from the traches, but birds with titres over log2 6 were always resistant. 相似文献
3.
鸡新城疫－传染性支气管炎－传染性法氏囊病三联灭活疫苗对不同日龄雏鸡的免疫效力研究 总被引：1，自引：1，他引：0
为评估鸡新城疫（ND）-传染性支气管炎（IB）-传染性法氏囊病（IBD）三联灭活疫苗对不同日龄和不同水平母源抗体雏鸡的免疫效力和持续期,本试验用该疫苗免疫7、14、21日龄SPF雏鸡和有母源抗体的普通雏鸡,免疫后采血测定ND血凝抑制抗体（HI Ab）、IB血凝抑制抗体（HI Ab）及IBD中和抗体（NA）,并用传染性法氏囊病病毒（IBDV）强毒攻击。结果显示,7日龄SPF雏鸡免疫后21 d ND HI抗体、IB HI抗体及IBD中和抗体效价分别为7.9log2、6.9log2和14.1log2,SPF鸡日龄越大,抗体水平越高;28日龄SPF鸡免疫后3个月,0.3 mL免疫剂量组试验鸡ND HI、IB HI及IBD中和抗体效价分别达6.5log2、6.1log2和13.6log2,IBDV攻毒保护率均为100%（10/10）;不同日龄普通雏鸡免疫效果与SPF鸡试验一致,抗体水平随鸡日龄增大而升高,IBD攻毒保护率也都达到100%（10/10）。试验结果证实,鸡新城疫-传染性支气管炎-传染性法氏囊病三联灭活疫苗可使7、14及21日龄SPF雏鸡和普通雏鸡产生良好的免疫力,对雏鸡的免疫期至少为3个月。 相似文献
4.
Bivalent Newcastle disease (ND)/infectious bursal disease (IBD) and trivalent ND/IBD/infectious bronchitis (IB) inactivated oil emulsion vaccines were prepared in the laboratory and evaluated under field conditions. Broiler breeder parent chickens previously vaccinated with live vaccines were inoculated with commercial monovalent ND and experimental bivalent or trivalent oil emulsion vaccines. The commercial vaccine induced a higher initial ND haemagglutination inhibition (HI) response than the experimental vaccines but, by 34 weeks after vaccination, the mean ND HI levels were not significantly different in any of the three flocks. All three vaccines provided sufficient ND immunity to protect against the clinical disease and egg production losses. The IBD responses of both flocks vaccinated with oil emulsion vaccine were similar to each other and only slightly lower than those flocks vaccinated with monovalent IBD oil emulsion vaccine in earlier experiments. Six weeks after vaccination, sufficient immunity was transferred to protect all the progeny against IBD challenge up to 33 days of age and some of them up to 45 days of age. Thirty-four weeks after vaccination of the parents with oil emulsion vaccine, the progeny were totally immune up to 27 days of age and some of them were immune until 37 days. Application of oil emulsion vaccines in bivalent or trivalent form did not impair the responses of the chickens to the monovalent components. 相似文献
5.
对应用当地分离病毒株研制的鸡产蛋下降综合症系列油乳剂灭活苗进行了免疫试验。结果表明,免疫后,鸡产蛋下降综合症（ＥＤＳ７６）油乳剂灭活苗、鸡新城疫（ＮＤ）－产蛋下降综合症二联油乳剂灭活苗及鸡新城疫－鸡传染性支气管炎（ＩＢ）－产蛋下降综合症三联油乳剂灭活苗免疫组的血清ＥＤＳ７６ＨＩ抗体迅速上升,维持４个月后仍在６．８－８（ｌｏｇ２）以上,并且能够抵抗强毒的攻击。证明所研制的ＥＤＳ７６油苗、ＮＤ－ＥＤＳ７６二联油苗、ＮＤ－ＩＢ－ＥＤＳ７６三联油苗对ＥＤＳ７６具有良好的免疫作用,能够抵抗ＥＤＳ７６强毒的攻击并产生高而持久的血清ＨＩ抗体。此外,对ＮＤ－ＥＤＳ７６二联苗、ＮＤ－ＩＢ－ＥＤＳ７６三联苗免疫组的血清ＮＤＨＩ抗体测定结果表明,上述二联苗、三联苗能产生与接种ＮＤ油苗一样良好的ＮＤ免疫效果,在免疫后１３０天时,其血清ＨＩ抗体仍高达９－１１（ｌｏｇ２）以上,与对照组有极显著的差异 相似文献
6.
Antibody responses in indigenous village and commercial chickens vaccinated with 12 thermostable Newcastle disease (ND) vaccine and protection levels against challenge with a virulent field isolate were determined. The antibody response of village chickens vaccinated by eye drop revealed that 30, 60 and 90 days after primary vaccination, the mean log2 HI titres were 6.1, 5.4 and 3.6, respectively, whereas for commercial chickens, the antibody response after 14, 30 and 90 days were 8.2, 5.1 and 4.2, respectively. Village chickens vaccinated orally via drinking water had mean log2 HI titres of 3.4 after 30 days. After booster vaccination, the mean HI titre was 5.4 and 3.3 after 30 and 60 days post-secondary vaccination (i.e. 60 and 90 days after primary vaccination). Antibody response of mean log2 HI titres of 2.6 was recorded 30 days after primary vaccination orally through food; 30 and 60 days after secondary vaccination (i.e. 60 and 90 days after primary vaccination), mean log2 HI titres were 5.3 and 3.2, respectively. All commercial and village chickens vaccinated by eye drop survived the challenge trial whereas village chickens vaccinated through drinking water and food had protection levels of 80% and 60% 30 days after primary vaccination, respectively. However, 30 days after booster vaccination, the protection level was 100%. At 60 days after secondary vaccination, the protection level dropped again to 80% for chickens vaccinated orally. All control chickens used in the challenge trials developed clinical ND and died 3-5 days after inoculation with the virulent virus. Supported by laboratory findings, I2 strain of NDV seemed to be avirulent, immunogenic and highly protective against virulent isolates of NDV. It may be a suitable vaccine to use in village chickens to vaccinate them against ND in rural areas. 相似文献
7.
Studies were performed to determine if mucosal vaccination with inactivated avian metapneumovirus (aMPV) subtype C protected turkey poults from clinical disease and virus replication following mucosal challenge. Decreases in clinical disease were not observed in vaccinated groups, and the vaccine failed to inhibit virus replication in the tracheas of 96% of vaccinated birds. Histopathologically, enhancement of pulmonary lesions following virus challenge was associated with birds receiving the inactivated aMPV vaccine compared to unvaccinated birds. As determined by an enzyme-linked immunosorbent assay (ELISA), all virus-challenged groups increased serum immunoglobulin (Ig) G and IgA antibody production against the virus following challenge; however, the unvaccinated aMPV-challenged group displayed the highest increases in virus-neutralizing antibody. On the basis of these results it is concluded that intranasal vaccination with inactivated aMPV does not induce protective immunity, reduce virus shedding, or result in decreased histopathologic lesions. 相似文献
8.
The present study was conducted to assess the haemagglutination-inhibition (HI) titres required to protect the chicken reproductive
tract against direct damage caused by Newcastle disease virus (NDV). Precociously induced oviduct and uterus by oestrogen
treatment of young chicks were used to assess the damage or protection against the damage by analysis of ciliostasis or histopathological
lesions. Unvaccinated day-old female white leghorn chickens were used as the maternally derived antibody (MDA) group. Chickens
were vaccinated with either a live lentogenic vaccine on day 14 of age or, along with it, an inactivated vaccine at day 36
of age, to generate birds with a range of primary or secondary response induced HI antibodies. Birds with different HI antibody
levels were challenged with virulent NDV. It was found that a HI antibody titre of 128 and above was protective against direct
damage of the reproductive tract, while the 32–64 titre range was protective when derived through secondary vaccination only. 相似文献
9.
IG BELL PJ NICHOLLS C. NORMAN AINI IDERIS† GM CROSS† 《Australian veterinary journal》1991,68(3):97-101
Meat chickens housed on a commercial broiler farm in Australia were vaccinated once at 10 to 11 days-of-age by aerosol with live V4 Newcastle disease virus (NDV) vaccine. Groups of vaccinated and unvaccinated birds were flown to Malaysia, where they were challenged with a virulent strain of NDV. Survival rates in vaccinated chickens challenged 7, 14, 21 or 31 d after vaccination were 0.47, 0.77, 0.97 and 0.92, respectively. All unvaccinated chickens died due to Newcastle disease (ND) following challenge. Chickens in Australia and Malaysia were bled and the serums tested for haemagglutination-inhibiting (HI) antibody to NDV. Many vaccinated birds with no detectable antibody, and all birds with a log2 titre of 2 or greater, survived challenge. The results showed that this V4 vaccine induced protective immunity in a significant proportion of chickens within 7 d of mass aerosol vaccination. This early immunity occurred in the absence of detectable circulating HI antibody. Non-HI antibody mediated immunity continued to provide protection up to 31 d after vaccination. Almost all vaccinated birds were protected within 3 w of vaccination. It is concluded that the V4 vaccine is efficacious and could be useful during an outbreak of virulent ND in Australia. 相似文献
10.
The role of cell-mediated immunity (CMI) in protection of birds from Newcastle disease was investigated by two different strategies in which only Newcastle disease virus (NDV)-specific CMI was conveyed without neutralizing antibodies. In the first strategy, selected 3-wk-old specific-pathogen-free (SPF) birds were vaccinated with either live NDV (LNDV), ultraviolet-inactivated NDV (UVNDV), sodium dodecyl sulfate-treated NDV (SDSNDV), or phosphate-buffered saline (PBS) (negative control) by the subcutaneous route. Birds were booster vaccinated 2 wk later and challenged with the velogenic Texas GB strain of NDV 1 wk after booster. All vaccinated birds had specific CMI responses to NDV as measured by a blastogenesis microassay. NDV neutralizing (VN) and hemagglutination inhibition (HI) antibody responses were detected in birds vaccinated with LNDV and UVNDV. However, birds vaccinated with SDSNDV developed antibodies that were detected by western blot analysis but not by the VN or HI test. Protection from challenge was observed only in those birds that had VN or HI antibody response. That is, birds with demonstrable CMI and VN or HI antibody response were protected, whereas birds with demonstrable CMI but no VN or HI antibody response were not protected. In the second strategy, birds from SPF embryos were treated in ovo with cyclophosphamide (CY) to deplete immune cells. The birds were monitored and, at 2 wk of age, were selected for the presence of T-cell activity and the absence of B-cell activity. Birds that had a significant T-cell response, but not a B-cell response, were vaccinated with either LNDV, UVNDV, or PBS at 3 wk of age along with the corresponding CY-untreated control birds. The birds were booster vaccinated at 5 wk of age and were challenged with Texas GB strain of NDV at 6 wk of age. All birds vaccinated with LNDV or UVNDV had a specific CMI response to NDV, VN or HI NDV antibodies were detected in all CY-nontreated vaccinated birds and some of the CY-treated vaccinated birds that were found to have regenerated their B-cell function at 1 wk postbooster. The challenge results clearly revealed that CY-treated birds that had NDV-specific CMI and VN or HI antibody responses to LNDV or UVNDV were protected, as were the CY-nontreated vaccinated birds. However, birds that had NDV-specific CMI response but did not have VN or HI antibodies were not protected from challenge. The results from both strategies indicate that specific CMI to NDV by itself is not protective against virulent NDV challenge. The presence of VN or HI antibodies is necessary in providing protection from Newcastle disease. 相似文献
11.
鸡新城疫、传染性支气管炎、减蛋综合征、传染性脑脊髓炎四联灭活疫苗IB部分效力试验研究 总被引：1，自引：0，他引：1
姜北宇institute of animal husbandry veterinary of Beijing academy agricultural forestry science 《中国兽药杂志》2009,43(1):17-20
采用《进口兽药质量标准》中传染性支气管炎灭活疫苗效力检验方法,对ND-IB-EDS76-AE四联灭活疫苗IB部分进行了效力检验。先用IBH120活疫苗作基础免疫,免疫后3～4周采血,然后用四联苗加强免疫,四联苗免疫后3～4周采血,将二次血清分别作IBHI试验。结果显示,IBH120活疫苗免后3～4周,其IBHI效价为3．6～4．610g2（1：12—1：24）,用四联苗加强免疫3～4周后,IBHI达6．2—8．610g2（1：74～1：388）,四联苗免后的IBm抗体滴度比免前提高了4．9～26倍,均大于3倍的标准。试验证明,该方法用于四联苗内IB部分效力检验是可行的。 相似文献
12.
To analyse the results of a vaccination on the first day of age against Newcastle disease (ND) and on the 17th day of age against Infectious Bronchitis (IB) resp. with spray vaccines with Clone 30 and H120 vaccine. These vaccinations are compared in field circumstances with other vaccination methods. A serological examination and challenge test were used to be informed about the response and protection. From the present study the following conclusions can be drawn: Clear indications are obtained that following a spray vaccination against ND with Clone 30 vaccine of one-day-old broilers which possessed maternal antibodies, birds received a moderately good protection against ND, in spite of very low levels of HI antibodies. A spray vaccination against IB with H120 vaccine of broilers at 17 days of age gave some protection from two weeks after vaccination, however making a good conclusion about the protection is impossible and further investigation is required. 相似文献
13.
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. 相似文献
14.
Vaccination against infectious bronchitis (IB) is aimed to protect against clinical IB. The question is, however, whether vaccinated birds are also protected against predisposure for colibacillosis after a subsequent IBV infection. We examined this research question in four experiments. One-day-old commercial broilers, housed in isolators, were vaccinated with IB vaccine strain H120 by coarse spray or ocularly. Twenty-eight days after vaccination, broilers were challenged with the virulent IBV strain M41. Five days later, broilers were inoculated with Escherichia coli strain 506. Body weight uniformity, severity of E. coli airsacculitis, and systemic E. coli infection at 7 days following E. coli inoculation were used as parameters for colibacillosis. IBV vaccination reduced both the number of broilers with E. coli airsacculitis as well as the severity of airsacculitis significantly after challenge with IBV-M41 and E. coli 506. However, in spray-vaccinated groups, no significant reduction of the number of birds with systemic colibacillosis or the severity of this infection was obtained, and body weight uniformity was not significantly improved compared with nonvaccinated, IBV-M41, and E. coli 506-challenged groups. Eye-drop vaccination resulted in conflicting results. 相似文献
15.
Use of an inactivated vaccine for prevention of parvovirus-induced reproductive failure in gilts 总被引：1，自引：0，他引：1
T T Brown M D Whitacre O W Robison 《Journal of the American Veterinary Medical Association》1987,190(2):179-181
Gilts from dams that had been inoculated with inactivated porcine parvovirus (PPV) vaccine before breeding became seronegative to PPV by 26 weeks of age. Vaccination of these gilts with inactivated PPV vaccine at 32 weeks of age resulted in an antibody response that peaked at about 2 weeks after vaccination, with -log10 mean hemagglutination inhibiting (HI) antibody titers of less than 2. In the first-year group (82 gilts), HI titers gradually decreased, 20% of the gilts being seronegative by 6 to 7 weeks after vaccination and 75% being seronegative by 16 weeks after vaccination. In the second-year group, 93 gilts were infected naturally by a field strain of PPV at about 11 weeks after single vaccination with inactivated PPV. Additionally, in the second year, 20 vaccinated and 6 nonvaccinated gilts were immune-challenged with virulent PPV at 10 to 12 weeks after vaccination. Neither field nor challenge PPV infection of vaccinated pregnant gilts caused reproductive failure, even though some of the gilts became seronegative for PPV before challenge. Our findings suggest that single vaccination of gilts with inactivated PPV vaccine should give adequate protection from PPV-induced reproductive failure, even though serum HI titers decrease to an undetectable level shortly before PPV infection. 相似文献
16.
The objective of the present study was to develop and evaluate a local vaccine (strain TPV-1) against Fowl pox (FP) in chickens.
Two separate groups of chickens were vaccinated with FP vaccine through oral (coated on oiled rice) and wing web stab routes,
respectively. The results showed that the haemagglutination-inhibition (HI) antibody titres in both vaccinated groups were
comparable and significantly higher (P < 0.05) than the control chickens. It was further revealed that 14 days after vaccination
HI GMT of ≥2 log2 was recorded in chickens vaccinated by oral and wing web stab routes whereas 35 days after vaccination the HI antibody titres
reached 5.6 log2 and 6.3 log2, respectively. Moreover, in both groups the birds showed 100% protection against challenge virus at 35 days after vaccination.
The findings from the present study have shown that oral route is equally effective as wing web stab route for vaccination
of chickens against FP. However, the oral route can be used in mass vaccination of birds thus avoid catching individual birds
for vaccination. It was noteworthy that strain TPV-1 virus could be propagated by a simple allantoic cavity inoculation and
harvesting of allantoic fluid where it survived exposure at 57°C for 2 hours. If the oral vaccination technique is optimized
it may be used in controlling FP in scavenging and feral chickens. In conclusion, the present study has shown that FP vaccine
(strain TPV-1) was safe, thermostable, immunogenic and efficacious in vaccinated chickens. 相似文献
17.
Shafqat F. Rehmani 《Preventive veterinary medicine》1996,25(3-4):241-248
Twelve-day-old chickens were vaccinated once with different Newcastle disease (ND) vaccines ( F, La Sota and Mukteswar) by two different routes (intraocular and drinking water). Chickens from a seventh group were uninoculated controls. At weekly intervals for 7 weeks after vaccination, 20 chickens from each vaccinated group and 20 chickens from the control group were examined for the production of haemagglutination-inhibition (HI) antibodies and for protection as assessed after challenge with velogenic, viscerotropic ND virus.
La Sota ND vaccine used intraocularly ranked the best and Mukteswar vaccine by the drinking water route the worst for their HI antibody titres prior to challenge. Differences between the treatments in protection were examined. For all three vaccines intraocular vaccine produced higher protection than drinking water vaccine. An inverse relationship between prechallenge and postchallenge HI titres was also recorded. 相似文献
18.
The novel vaccination technique for feral pigeons was developed in the present study. Multi-age feral pigeons were vaccinated
orally with Newcastle disease (ND) strain I-2 vaccine coated on oiled rice. The results showed that 14 days after vaccination
40% of pigeons seroconverted with HI GMT of ≥3 log2 whereas 28 days after vaccination the seroconversion rate of these birds reached 100%. Moreover, all vaccinated pigeons survived
the challenge of virulent Newcastle disease virus (NDV). The findings from the present study indicated that the use of ND (strain I-2) vaccine in feral pigeons is feasible
and resulted into the production of protective antibody response. Thus ND I-2 vaccine may prevent the spread of NDV to other
birds particularly chickens. Furthermore the use of oral vaccine in feral multi-age pigeons overcomes the difficulty of catching
these birds for individual vaccination. 相似文献
19.
It has been recommended that modern equine influenza vaccines should contain an A/equi-1 strain and A/equi-2 strains of the American and European-like subtype. We describe here the efficacy of a modern updated inactivated equine influenza-herpesvirus combination vaccine against challenge with a recent American-like isolate of equine influenza (A/equine-2/Kentucky/95 (H3N8). The vaccine contains inactivated Influenza strains A-equine-1/Prague'56, A-equine-2/Newmarket-1/'93 (American lineage) and A-equine-2/ Newmarket-2/93 (Eurasian lineage) and inactivated EHV-1 strain RacH and EHV-4 strain V2252. It is adjuvanted with alhydrogel and an immunostim. Horses were vaccinated at the start of the study and 4 weeks later. Four, six and eight weeks after the first vaccination high anti-influenza antibody titres were found in vaccinated horses, whereas at the start of the study all horses were seronegative. After the challenge, carried out at 8 weeks after the first vaccination, nasal swabs were taken, rectal temperatures were measured and clinical signs were monitored for 14 days. In contrast to unvaccinated control horses, vaccinated animals shed hardly any virus after challenge, and the appearance of clinical signs of influenza such as nasal discharge, coughing and fever were reduced in the vaccinated animals. Based on these observations, it was concluded that the vaccine protected against clinical signs of influenza and, more importantly, against virus excretion induced by an American-like challenge virus strain. In a second experiment the duration of the immunity induced by this vaccine was assessed serologically. Horses were vaccinated at the start of the study and 6 and 32 weeks later. Anti-influenza antibody titres were determined in bloodsamples taken at the first vaccination, and 2, 6, 8, 14, 19, 28, 32, 37, 41, 45 and 58 weeks after the first vaccination. Vaccinated horses had high anti-influenza antibody titres, above the level for clinical protection against influenza, against all strains present in the vaccine until 26 weeks after the third vaccination. 相似文献
20.
J Oravainen M Hakala E Rautiainen P Veijalainen M Heinonen A Tast JV Virolainen OAT Peltoniemi 《Reproduction in domestic animals》2006,41(1):91-93
This study was conducted to determine the antibody response for porcine parvovirus (PPV) of 39 gilts in field conditions after vaccination. Gilts from four herds endemically infected with PPV were injected twice with a commercial vaccine of inactivated PPV and Erysipelothrix rhusiopathiae. The PPV antibodies were analysed both with haemagglutination inhibition (HI) and enzyme-linked immunosorbent assay (ELISA) in order to study the agreement between these methods. The possible association between high-antibody titres and reproductive failure (repeat breeding, culling for infertility, < or = 6 piglets born alive) was also investigated. In these study herds, endemically infected by PPV, most gilts (84.6%) had not seroconverted by the age of 6 months. On-field vaccination resulted in a consistent increase of humoral immunity not exceeding the antibody level of 1 : 512 in the majority of gilts in all herds examined. The agreement between ELISA and HI tests was moderate (Spearman's rho = 0.87, kappa = 0.63). The seroconversion over the level >1:512 by mid-pregnancy was not associated with reproductive failure. 相似文献