Study On The Very Early Diagnosis Strategy And Its Influencing Factors Of HIV-exposed Infants

BackgroundHuman Immunodeficiency Virus(HIV)is a major public health problem of the world.It also poses a serious threat to women and children.The disease progreion are rapid for infants infected with HIV due to mother-to-child transmission.And they have high mortality rate about 50%-60%within 2 years of age.In order to reduce the their mortality rate,World Health Organization(WHO)had recommend that detedted in 48 hours after the infants birth could improve the survival rate of positive infants.According to Chinese current Early Infants Diagnosis(EID),the detection times of HIV-exposed infants are 6 weeks old and 3 months old.Although it could guaranteethis the high sensitivity and specificity of this strategy,it is achieved by delaying the detection time and could not meet the needs of the early treatment for positive ones.Since HIV-exposed infants obatined antibodies from their mothers after birth,the current EID dependend on qualitative testing of HIV nucleic acids.According to previous studies,Roche V2.0 is consider as the gold standard for EID.However,due to the high sensitivity,the use of this detection method is prone to false positive test results.Therefore,WHO recommends that the Cycle threshold(Ct)<33.0 could be used as the positive result evaluation standard,and the result of Ct)33.0 is taken as the uncertainty result.The Ct is the number of cycles experienced by the fluorescent signal in each reaction tube in the polymerase chain reaction(PCR)when the fluorescence signal reaches a set threshold.The high value of Ct may be related to the low Viral Load(VL).And in previous studies,the incidence of high Ct samples in reactive results is related the ages of sample collected,samples with high Ct during the first month of age are much higher than those at the age of three months.Therefore,the lower collecting age samples,the inclusion of Ct in the evaluation criteria can effectively reduce the false positive rate.But this standard has not been applicaten in the HIV-exposed infants detection in China yet.For the expensive cost,the complicating operation,and the strict testing environment of qualitative detection of nucleic,it is difficult to promote nationwide.Therefore,there is a need for research on the use of antibody detection to aid HIV EID.According to previous studies,there was a significant difference in the trend of antibody between negative infants and positive ones with age.Previous literature tends to focus on describing the differences in S/CO values between them,and there is shortage on studies of differences in specific antibody band variations.Therefore,there are still insufficient descriptions of the differences in the specific antibody strips between the positive and the negative.Therefore,based on the existing HIV EID strategy in China,this study is expected to be the first early diagnosis of nucleic acid as early as possible,and to explore the best strategy.According to the criteria recommended by WHO,whether the Ct values should included in the evaluation of test results.Exploring the trends of the antibody by measuring the antibody S/CO value and detecting specific antibody strips,to consider if the results of antibody test could used to assist in EID.Objectives1.Exploring the very early diagnosis strategy of HIV-exposed infants.2.In the nucleic acid qualitative detection of EID,whether Ct<33.0 should be used as a positive evaluation standard.3.To study the trends of antibody of HIV-infected infants,to provide a reference for EID by antibody test.Objects and samplesThe subjects of this study were infants who childbirthed by HIV-infected pregnant women that received detection and treatment after 36 weeks of gestation or during childbirth in the study areas of Yunnan,Sichuan,Xinjiang,Guangdong and Guangxi,and collected dried blood spots from heel blood of different ages.The actual infection status of'infants was determinated by National Gguideline for Detection of HIV/AIDS(2015).Methods1.Study on the very early diagnosis strategy of HIV exposed infants.There are 199 HIV exposed infants in this study,187 are infected and others are uninfected according to the gold standrand.Combined EID recommended by WHO,6 strategies are proposed in this study.Accoding them,collecting samples from 199 infants on their ages of 0-48 hours,48 hours to 4 weeks,4-6 weeks,and 3 months.The samples were detected by Roche V2.0,and the results were statistically analyzed.For the differences of ages when samples collecting and strategies,calculating the sensitivity and the spectivity of detections and the value of 95%CI by SAS9.3.2.The influence of Ct value on the judgment of early diagnosis results of infants.977 samples from 243 HIV exposed infants were included in this study.According to the gold standrand,224 are uninfected,891 samples from them,and 86 samples from others who are infected.The 977 samples were collected from the heel 4 weeks before,4 weeks to 3 months,3 months after of these infants.Qualitative detection of HIV nucleic acid was performed on samples using the Roche Human Immunodeficiency Virus(type 1)nucleic acid qualitative test kit.Divideing the samples into different groups,the sensitivity and specificity of samples of different age groups were calculated by Ct value<33.0 as the positive result standard.The samples with Ct value>33.0 were repeatedly tested to calculate the negative rate of retest.3.Study on the change of antibody in HIV exposed infants.There are 72 samples collected from born to 6 months age from 20 uninfected infants and 4 infected ones,as for 9 months age after,20 samples from 18 uninfected infants,9 samples from 5 infected ones.The samples were collected on the age of objects when they were 3-month-old,and 6-month-old heel-bearing blood at 36 weeks after pregnancy or at birth in Yunnan,Sichuan,Guangxi,Xinjiang,and Guangdong provinces.The S/CO value of the samples were detected by enzyme-linked immunosorbent assay,and the difference between the S/CO values of the same age group of the negative infant and the positive infant was statistically analyzed using the Wilcoxon rank sum test or t test by SAS9.3 software;the stripping reagent was used to detect the antibody band of the samples,and the differences in sample-specific banding between the negative and the positive infants was observed before 18 months.ResultsI.StLudy on the very early diagnosis strategy of HIV exposed infants.Seven HIV-positive infants were tested for infection within 0-48 hours,and all positive infants were tested for infection at 3 months of age.The sensitivitie of detection on the periods of 0-48 hours,48 hours-4 weeks,4 weeks-6 weeks and 3 months are 70.0%,87.5%,93.8%,and 100.0%respectively;and the detection specificities are 98.8%,99.6%,99.2%,100.0%and 100.0%respectively.There are small part of infants be defined as results-uncertain in 6 detection strategies,the work efficiencies of them are good performance,the sensitivities of the detection strategies of 1 to 5 are 71.4%,87.5%,100.0%,100.0%,95.7%,and 100.0%respectively,and all the specificities of them are 100.0%.2.The influence of Ct on the judgment of early diagnosis results of infants.After the Ct was 33.0 as the boundary between the positive and the uncertain samples,81 samples were judged as positive results and 28 samples were indeterminate.The proportion of uncertain samples for reach higher with the ages growing.After the uncertainty samples were excluded,the sensitivity and specificity of the time points after 3 months of age were 100.0%,and there are 28 and 24 positive samples the time points before 4 weeks and 4 weeks to 3 months respectively.25 and 22 positive samples of them were detected,and the detection specificities of the two time periods were 99.5%and 100.0%,respectively.24 uncertain samples received retesting,20 of the results are negative,18 retest results were consistent with the actual state of the sample.3.Study on the change of antibody in HIV exposed infants.The values of antibody S/CO of samples from negative infants decreased with the ages;while the positive ones are reduce first and then grow.As for RIBA,all the specific antibody bands of the negative samples gradually disappeared with age,the specific resolution rate is related to the class in the strip.The color of the positive sample-specific antibody bands showed a regressive trend within 3 months,and the rate of regression of each band was similar to that of the negative sample;after 3 months,the gp 160,gp41,p24 bands began to turn positive.Conclusions1.Infants can be diagnosed as infected while the result of 0-48 hours and 48 hours to 4 weeks of birth are positive.Therefore,the time infected infants could be detected advanced 6 weeks while it is used to supplement the original detection strategy of China2.The younger the infants at the time of samples collection,the higher the incidence rate of uncertain samples.The Ct should be regarded as the strandard of results when testing samples of infants,for it can reduce the false positive.3.They are different in the change rules of antibody S/CO and the spectial strips between samples from negative infants and positive ones,it can be used in the EID.