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The constant pretension of people for food indicates the importance of agriculture and technology, and places them among the most important economic branches. Agriculture in the modern world ensures the general progress of society in the economic and cultural aspects and represents an economic branch that ensures the material survival of mankind. Given the fact that the world's population is growing faster and that the need for daily food is constantly increasing, it is neces sary to start as soon as possible with the implementation of sustainable methods in agricultural production at all levels. Corn, as an agricultural product, is of great importance for the sustainable development of agriculture and belongs to field wide-row crops, which belongs to the group of cereals. Cultivation of this culture is best achieved in climatic conditions, from moderate to tropical, where in the periods of the year when daily average temperatures do not fall below 15 °C, they belong to C-4 plants, which do not tolerate low temperatures. New varieties and hybrids of corn enable higher and more stable yields in different climates, which implies that the correct selection of hybrids is sustainable development, not only for the corn crop and its price as a product on the cereal market. The subject of the paper is to point out the importance of sustainable development for the corn market as an agricultural product. The aim of the work is to assess the possibility of sustainable corn production in order to create a competitive product for the foreign market, as well as the potential and advantages of Serbia for the implementation of new or corrected production technologies that are characterized by respect for the principles of sustainable development.

The aim of this paper is to determine the effects of the transition on the standard of living and social inequality in Poland, Hungary, Slovenia and Russia. In order to establish a market economy, these countries started economic and systemic reforms at the end of the 1980s. The goal of the transition was the establishment of a market economy and macroeconomic stability, and to ensure a higher standard of living because (with the exception of Slovenia) the GDP per capita in these countries was significantly lower than the average of the EU countries. Although they applied different approaches in the implementation of the transition, it is characteristic for all countries that in the first phase of the transition (until the mid-1990s), they had the problem of recession and hyperinflation, which, together with the inadequate privatization process, was reflected in the decline of the standard of living (in Slovenia and Russia) and the growth of inequality. Only after establishing institutional reforms and attracting FDI, in the second transition phase (until the end of the 1990s), macroeconomic stability was established, which contributed to the growth of living standards (except for Russia) and the reduction of inequality (except in Poland).

Faced with high levels of poverty, China introduced its "one-child policy" in 1980 and began economic and systemic reforms that led to the country''s strong economic development. Thanks to the improvement in the average standard of living, certain socioeconomic aspects related to women''s employment, the pursuit of higher education, delays in childbirth, and the number of children have changed. These changes have not only reduced the number of children being born and led to population aging, but have also affected the labour market. The aim of this paper is to determine the effects of Chinese population policy on selected labour market indicators: labour force by age and sex in rural/urban areas, the labour force participation rate, and the unemployment rate. Research results from 2010 to 2020 show the growth of the labour force, while the unemployment rate has been growing since 2018. It is noticeable that the number of workers in the labour force is growing in cities, while it is declining in rural areas. On the other hand, the unemployment rate is lower in rural areas, while the growth of unemployment is evident in urban areas. The research shows that the long-term implementation of this population policy has resulted in a larger number of men, leading to greater participation of men in the labour force. Despite measures to improve the position of women at work, women''s social security is still not guaranteed, and it is more difficult for women to decide to expand their families. As China has ambitious plans for economic development, defining adequate population and social policies is crucial for their implementation.

The Western Balkans countries have the aim to become part of the European Union. According to that aim, they have implemented economic and systemic reforms in the last three decades. As countries in the region are signatories to the Energy Community Treaty, they have committed themselves to harmonize legislation, define and implement national plans aimed at reducing carbon emissions, improving energy efficiency and increasing the use of renewable energy sources. Having in mind their commitment, the aim of this paper is to determine the progress in the process of economic development, i.e. to define the chances and limitations to implement the process of energy transition. The results of the research show that despite the started reform processes and the progress in the Human Development Index, the COVID-19 crisis slowed down the development of the region and led not only to recession and falling living standards, but also to rising unemployment. In addition, a great challenge for the region is the reduction of energy and carbon intensity because the structure of the power industry is dominated by coal-fired power plants that are outdated and inefficient. The region lacks investment and consistency in implementing ongoing reforms. The Green Agenda for the Western Balkans represents a chance for the region, because through the Instruments of Cross-Border Cooperation, it encourages investments in projects that not only enable energy transition, but also the development of other sectors of industry and agriculture.

In the 1980s, the neoliberal concept was imposed as an economic-political doctrine based on the claim that the free market efficiently allocated resources and ensured world prosperity and peace. The aim of this paper is to try to provide one of the possible interpretations of neoliberal economy on the basis of the analysis of the development of economic thought. The foundations of liberal economy are defined by classical political economy, and the contribution was made by the neoclassical school of economics, but also other directions in the development of economic thought. Although proponents of the neoliberal economy have advocated liberalization and privatization to improve the general well-being of society, the global economic crisis and the COVID-19 crisis have shown the misconceptions and contradictions of neoliberal results that are not only ineffective in times of crisis but also contribute to global inequality.

Recently, growing interest has been devoted to the investigation of compounds with antimicrobial activity due to rising cases of resistance of microbes to known therapies. A reliable and versatile source of novel drug discovery was recently found among endophytic fungi. Hitherto, the research usually enclosed the in vitro evaluation of antimicrobial activity and chemical structure elucidation of biomolecules extracted from fungal material. Therefore, this research was designed as an extension to previous investigations of endophytic fungi growing on conifer needles by means of conducting a molecular docking study. The in silico methods were used with the main goal to make a contribution to the understanding of the mechanisms underlying the interaction of biomolecules isolated from fungus Phomopsis species and eight different types of receptors that belong to usually multidrug resistant bacterial pathogens. The results revealed valuable interactions with receptors 3G7B (Staphylococcus aureus’s gyrase B), 1F0K (1.9 Å structure of Escherichia coli’s transferase) and 1SHV (Klebsiella pneumoniae’s SHV-1 β-lactamase) thus pointing out the receptors that trigger antibiotic response upon activation by the most potent compounds 325-3, 325-5, phomoenamide and phomol. These findings also recommended further discovery of novel potent and broadspectrum antibiotics based on the structure of selected molecules.

Hot-melt coating (HMC) is an alternative, solvent-free coating method generally used to modify substrate release rate and/or mask its unpleasant taste. The aim of this study was to assess two HMC methods (pan-coating and mortar-coating) by assaying functional properties of the coated material. The selected substrates included highly soluble sodium chloride (model substance) and caffeine (bitter drug), and the coating agent was glycerol distearate without/with the addition of liquid paraffin. Experiments with sodium chloride revealed that pan-coating yielded particles of more regular shape, while mortar-coating yielded samples of more uniform coating layer. The flowability of the coated material depended on the particle size. Sustained sodium chloride release was achieved for all mortar-coated and some pan-coated samples. The analysis of the results indicated mortar-coating as a preferable HMC method for caffeine coating. The resulting caffeine yield in the coated samples was high (99%), the material showed satisfactory mechanical properties and drug release from the coated particles was sustained. Overall, the obtained results suggest that both pan-and mortar-coating can be used to sustain the release of drugs with unpleasant taste, but mortar-coating can be considered as a more simple and practical method that can be potentially used in compounding pharmacies.

Computer-based (in silico) modeling & simulation tools have been embraced in different fields of pharmaceutics for a variety of applications. Among these, physiologically-based pharmacokinetic/biopharmaceutics modeling (PBPK/PBBM) emerged as a particularly useful tool in formulation development. PBPK/PBBM facilitated strategies have been increasingly evaluated over the past few years, as demonstrated by several reports from the pharmaceutical industry, and a number of research and review papers on this subject. Also, the leading regulatory authorities have recently issued guidance on the use of PBPK modeling in formulation design. In silico PBPK models can comprise different dosing routes (oral, intraoral, parenteral, inhalation, ocular, dermal etc.), although the majority of published examples refer to modeling of oral drugs performance. In order to facilitate the use of PBPK modeling tools, a couple of companies have launched commercially available software such as GastroPlus™, Simcyp™ PBPK Simulator and PK-Sim®. This paper highlights various application fields of PBPK/PBBM modeling, along with the basic principles, advantages and limitations of this approach, and provides relevant examples to demonstrate the practical utility of modeling & simulation tools in different stages of formulation development.

Drug resistance, especially bacterial antibiotic resistance, is recognized as a global phenomenon. Potential of endophytic fungi as producers of secondary metabolites with wide spectra of different bioactivities in the field of drug discovery has recently been introduced. The production of these compounds is under the great impact of the variety of factors related to the choice of plant host, climate conditions, nutrition, presence of other microorganisms in the same surrounding, etc. Due to a large number of different indices of endophytic fungi antibacterial activity, critical evaluation with the assistance of data mining analytical methods was performed. The activity towards several pathogen bacteria of endophytes species growing on different plant hosts, deciduous trees as well as herbaceous plants spread worldwide in different climatic zones together with the taxonomy of endophytes was taken into consideration. The principal component analysis was used to explore formed big data set and through finding patterns in data, to point out to a limited number of proper candidates for future pharmaceutical research. The antimicrobial character of Phomopsis species was highlighted and future perspectives in their therapeutic use were projected.

Mining is a global industry that is of great importance for every product which is used by human. For mining, process efficiency, reducing production downtime, increasing profitability are all very important. Soft computing technologies (SC) are helping in the process of transforming the mining industry into a safer and more environmental friendly industry, but keeping in mind the financial aspect as well. In this paper some of fields of blasting activities in which the SC methods have been applicated, will be presented. Trough the following chapters some of the most significant researches will be reviewed.

Introduction/Objective. The ideal reconstruction procedure after total gastrectomy should replace all lost functions of the stomach. The aim of this study was to evaluate the usefulness of preserving the duodenal passage in subsequent improvement of body weight (BW) and body mass index (BMI) in patients with gastric cancer after total gastrectomy. Methods. A total of 30 patients with gastric cancer were prospectively randomly divided into a group of reconstruction with double-tract (n = 15) and a group of reconstruction with simple Roux-en-Y after total gastrectomy. They were stratified by sex, age, their anthropometric measurements (BW, BMI), primary tumor localization, Lauren’s classification, TNM stage classification, length of hospital stay, operation duration, postoperative complications, and mortality. Postoperatively, BW and BMI were measured at three, six, and 12 months and compared between the two groups. Results. The clinical group of double-tract patients had significantly higher the values of BW in the postoperative period after six (66.6 ± 4.9 vs. 61.7 ± 7.6; p < 0.05 paired Student’s t-test) and after 12 months (67.0 ± 4.9 vs. 62.3 ± 7.2; p < 0.05 paired Student’s t-test) compared to the group of Roux-en-Y patients. On the other hand, the clinical group of double-tract patients also had significantly higher the values of BMI in postoperative period after 12 months (23.6 ± 1.1 vs. 22.5 ± 1.6; p < 0.05 paired Student’s t-test) in relation to the Roux-en-Y group of patients. Conclusion. Reconstruction procedure carried out after total gastrectomy which implies preserving the duodenal passage has significant increase of BW and BMI, compared to reconstruction procedure without the preservation of the duodenal passage.

Background/Aim. Rectal cancer is a major health problem throughout the world, despite the great progress in the treatment and control of the disease. The aim of this study was to determine the effect of mesorectal excision type on local recurrence in patients operated on for rectal cancer within a 3- year period. Methods. The clinical retrospective study was conducted at the Clinic for General Surgery at the Clinical Center in Niš, Serbia, and included 225 patients with rectal cancer. Postoperatively, the patients were observed 36 months. Total mesorectal excision (TME) method was used in 129 (57.33%) patients, and partial mesorectal excision (PME) in 96 (42.66%). There were 145 (64.44%) man and 80 (35.55%) women, average age 66.8 years. Results. In 58 (25.77%) of the patients cancer was localized in the proximal third of the rectum, in 99 (44%) in the medium third, in 68 (30.22%) it was 8 cm of the anocutaneous line. In 167 (74.22%) patients rectal cancer was in T3 stadium. TME was performed in all the patients with cancer in the distal third of the rectum and in 61.61% of the patients with cancer in the medium third of the rectum. PME was performed in all the patients with localized cancer in the proximal third and in 38.38% of the patients with cancer in the medium third of the rectum. Local recurrence occurred in 20 (8.88%) patients, 12 (9.30%) in the TME group and 8 (8.33%) in the PME group, which was not a statistically significant difference. In 75% of the cases, relapse occurred in the patients in T3 stage. Relapse occurred in 55% of the cases in the second year after the surgery. The median survival of all the patients amounted to 35 months. The total mortality of all respondents in a 3-year period amounted to 5.3%. Conclusion. There were no statistically significant differences in the incidence of local recurrence and survival among patients who underwent TME and those underwent PME. The type of mesorectal excision does not affect the incidence of local recurrence in node-negative disease stages.

Background/Aim. Magnetic resonance imaging (MRI) is a key modality not only for lesion diagnosis, but also to evaluate the extension, type and grade of the tumor. Advanced MRI techniques provide physiologic information that complements the anatomic information available from conventional MRI. The aim of this study was to determine whether there is a correlation between apparent diffusion coefficient (ADC) maps of intracranial glial tumors and histopathologic findings and whether ADCs can reliably distinguish lowgrade from high-grade gliomas. Methods. This retrospective study included 25 patients with MRI examination up to seven days before surgery, according to the standard protocol with the following sequences: T1WI, T2WI, FLAIR, DWI and post contrast T1WI. Data obtained from DW MRI were presented by measuring the value of ADC. The ADC map was determined by utilizing Diffusion-Perfusion (DP) Tools software. All the patients underwent surgical resection of the tumor. Histological diagnosis of tumors was determined according to the World Health Organization (WHO) classification. The ADC values were compared with the histopathologic findings according to the WHO criteria. Results. The ADC values of astrocytomas grades I (0.000614 ± 0.000032 mm2/s) were significantly higher (< 0.001) than the ADC values of anaplastic astrocytomas (0.000436 ± 0.000016 mm2/s) and the ADC values of glioblastomas multiforme (0.000070 ± 0.000008 mm2/s). The ADC values of astrocytomas grades II (0.000530 ± 0.000114 mm2/s) were significantly higher (< 0.001) than the ADC values of anaplastic astrocytomas (0.000436 ± 0.000016 mm2/s) and glioblastomas multiforme (0.000070 ± 0.000008 mm2/s). The ADC values of anaplastic astrocytomas (0.000436 ± 0.000016 mm2/s) were significantly higher (< 0.001) than the ADC values of glioblastomas multiforme (0.000070 ± 0.000008 mm2/s). The ADC values in the cystic part of the tumor for astrocytomas grades I (0.000775 ± 0.000023 mm2/s) were significantly higher (< 0.001) than the ADC values of anaplastic astrocytomas (0.000119 ± 0.000246 mm2/s) and glioblastomas multiforme (0.000076 ± 0.000004 mm2/s). The ADC values astrocytomas grades II (0.000511 ± 0.000421 mm2/s) were significantly higher (< 0.001) than the ADC values of glioblastomas multiforme (0.000076 ± 0.000004 mm2/s). Concluson. DWI with calculation of ADC maps can be regarded as a reliable useful diagnostic tool, which indirectly reflects the proliferation and malignancy of gliomas. The ADCs maps can both predict the results of histopathological tumor and distinguish between low- and high-grade gliomas, and provide significant information for presurgical planning, treatment and prognosis for patients with highgrade astrocytomas.

The development of novel dry powders for dry powder inhalers (DPIs) requires the in vitro assessment of DPI aerodynamic performance. As a potential complementary method, in silico numerical simulations can provide additional information about the mechanisms that guide the particles and their behavior inside DPIs. The aim of this study was to apply computational fluid dynamics (CFDs) coupled with a discrete phase model (DPM) to describe the forces and particle trajectories inside the RS01 ® as a model DPI device. The methodology included standard fluid flow equations but also additional equations for the particle sticking mechanism, as well as particle behavior after contacting the DPI wall surface, including the particle detachment process. The results show that the coefficient of restitution between the particle and the impact surface does not have a high impact on the results, meaning that all tested combinations gave similar output efficiencies and particle behaviors. No sliding or rolling mechanisms were observed for the particle detachment process, meaning that simple bouncing off or deposition particle behavior is present inside DPIs. The developed methodology can serve as a basis for the additional understanding of the particles' behavior inside DPIs, which is not possible using only in vitro experiments; this implies the possibility of increasing the efficiency of DPIs.

In vitro assessment of dry powders for inhalation (DPIs) aerodynamic performance is an inevitable test in DPI development. However, contemporary trends in drug development also implicate the use of in silico methods, e.g., computational fluid dynamics (CFD) coupled with discrete phase modeling (DPM). The aim of this study was to compare the designed CFD-DPM outcomes with the results of three in vitro methods for aerodynamic assessment of solid lipid microparticle DPIs. The model was able to simulate particle-to-wall sticking and estimate fractions of particles that stick or bounce off the inhaler's wall; however, we observed notable differences between the in silico and in vitro results. The predicted emitted fractions (EFs) were comparable to the in vitro determined EFs, whereas the predicted fine particle fractions (FPFs) were generally lower than the corresponding in vitro values. In addition, CFD-DPM predicted higher mass median aerodynamic diameter (MMAD) in comparison to the in vitro values. The outcomes of different in vitro methods also diverged, implying that these methods are not interchangeable. Overall, our results support the utility of CFD-DPM in the DPI development, but highlight the need for additional improvements in these models to capture all the key processes influencing aerodynamic performance of specific DPIs.

This study aims to understand the absorption patterns of three different kinds of inhaled formulations via in silico modeling using budesonide (BUD) as a model drug. The formulations investigated in this study are: (i) commercially available micronized BUD mixed with lactose (BUD-PT), (ii) BUD nanocrystal suspension (BUD-NC), (iii) BUD nanocrystals embedded hyaluronic acid microparticles (BUD-NEM). The deposition patterns of the three inhaled formulations in the rats' lungs were determined in vivo and in silico predicted, which were used as inputs in GastroPlus™ software to predict drug absorption following aerosolization of the tested formulations. BUD pharmacokinetics, estimated based on intravenous data in rats, was used to establish a drug-specific in silico absorption model. The BUD-specific in silico model revealed that drug pulmonary solubility and absorption rate constant were the key factors affecting pulmonary absorption of BUD-NC and BUD-NEM, respectively. In the case of BUD-PT, the in silico model revealed significant gastrointestinal absorption of BUD, which could be overlooked by traditional in vivo experimental observation. This study demonstrated that in vitro-in vivo-in silico approach was able to identify the key factors that influence the absorption of different inhaled formulations, which may facilitate the development of orally inhaled formulations with different drug release/absorption rates., Competing Interests: The authors declare that there is no conflict of interest., (© 2021 Shenyang Pharmaceutical University. Published by Elsevier B.V.)

The aim of this study was to optimize the parameters of the complex melt-emulsification process coupled with the spray-drying, in order to maintain the balance between solid lipid microparticles (SLMs) powders aerodynamic performance and salbutamol sulfate release rate. Quality target product profile was identified and risk management and principal component analysis were used to guide formulation development. Obtained dry powders for inhalation (DPIs) were evaluated in terms of SLMs size distribution, morphology, true density, drug content, solid state characterization studies, in vitro aerosol performance and in vitro drug release. SLMs micrographs indicated spherical, porous particles. Selected powders showed satisfactory aerosol performance with a mean mass aerodynamic diameter of around 3 μm and acceptable fine particle fraction (FPF). Addition of trehalose positively affected SLMs aerodynamic properties. The results of in vitro dissolution testing indicated that salbutamol sulfate release from the tested SLMs formulations was modified, in comparison to the raw drug release. In conclusion, SLMs in a form of DPIs were successfully developed and numerous factors that affects SLMs properties were identified in this study. Further research is required for full understanding of each factor's influence on SLMs properties and optimization of DPIs with maximized FPFs., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Recently, growing interest is devoted to investigation of bioactive secondary metabolites of endophytic fungi. Thus, as an extension to our previous achievements related to antimicrobial potential of endophytic fungi, Phomopsis species isolated from conifer needles was selected as appropriately promising natural source for drug discovery. Its dichloromethane and ethanol extracts considerably inhibited growth of Escherichia coli and Staphylococcus aureus. Moreover, the individual compounds of dichloromethane extract have been separated, collected and purified using semi preparative liquid chromatographic analysis and comprehensively characterized using mass spectrometry (MS) and nuclear magnetic resonance spectroscopy (NMR). Based on their antimicrobial activity and unique structural characteristics in comparison with well-established drugs from the same therapeutic category, two dominant compounds (Z)-(Z)-2-acetoxyprop-1-en-1-yl-3-(3-((E)-3,4-dihydroxypent-1-en-1-yl)oxiran-2-yl)acrylate (denoted as 325-3) and (Z)-(Z)-2-acetoxyprop-1-en-1-yl 3-(3-((E)-4-hydroxy-3-oxopent-1-en-1-yl)oxiran-2-yl)acrylate (denoted as 325-5) were recognized as valuable leading structures for future discovery of novel antibiotics.

Posterior reversible encephalopathy syndrome (PRES) is an obstetric emergency frequently occurring in a pregnant or puerperal woman, manifested with an acute headache, consciousness impairment, seizures, and visual deficits and is associated with white matter changes predominantly affecting the posterior parietal and occipital lobes of the brain. Apart from the above-described typical location of the changes, the most common atypical location involves the brain stem and basal ganglia. Since magnetic resonance imaging (MRI) is more sensitive and specific imaging technique compared to computerized tomography, establishing the diagnosis and follow-up in patients with PRES is based mainly on MRI findings. It is particularly important not to exclude PRES as a possible diagnosis when we have the appropriate clinical presentation accompanied by the atypical radiological findings, since this clinical-radiological syndrome can often be manifested with an atypical MRI image.

Inter-laboratory verification of European pharmacopoeia (EP) monograph on derivative spectrophotometry (DS) method and its application for chitosan hydrochloride was carried out on two generation of instruments (earlier GBC Cintra 20 and current technology TS Evolution 300). Instruments operate with different versions of Savitzky-Golay algorithm and modes of generating digital derivative spectra. For resolution power parameter, defined as the amplitude ratio A/B in DS method EP monograph, comparable results were obtained only with algorithm's parameters smoothing points (SP) 7 and the 2nd degree polynomial and those provided corresponding data with other two modes on TS Evolution 300 Medium digital indirect and Medium digital direct. Using quoted algorithm's parameters, the differences in percentages between the amplitude ratio A/B averages, were within accepted criteria (±3%) for assay of drug product for method transfer. The deviation of 1.76% for the degree of deacetylation assessment of chitosan hydrochloride, determined on two instruments, (amplitude (1)D202; the 2nd degree polynomial and SP 9 in Savitzky-Golay algorithm), was acceptable, since it was within allowed criteria (±2%) for assay deviation of drug substance, for method transfer in pharmaceutical analyses., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Infectious bronchitis virus (IBV) is prevalent in all countries with an intensive poultry industry, with the incidence of infection approaching 100% in most locations. Vaccination is only partially successful due to the continual emergence of antigenic variants. At many sites, multiple antigenic types are simultaneously present, requiring the application of multiple vaccines. Although many countries share some common antigenic types, IBV strains within a geographic region are unique and distinct, examples are Europe, the United States of America and Australia. Measures to restrict the introduction of exotic IBV strains should therefore be considered. Infectious bronchitis has a significant economic impact; in broilers, production losses are due to poor weight gains, condemnation at processing and mortality, whilst in laying birds, losses are due to suboptimal egg production and downgrading of eggs. Chickens and commercially reared pheasants are the only natural hosts for IBV. Other species are not considered as reservoirs of IBV. The majority of IBV strains cause tracheal lesions and respiratory disease with low mortality due to secondary bacterial infections, primarily in broilers. Nephropathogenic strains, in addition to tracheal lesions, also induce prominent kidney lesions with mortality of up to 25% in broilers. Strains of both pathotypes infect adult birds and affect egg production and egg quality to a variable degree. Infected chicks are the major source of virus in the environment. Contaminated equipment and material are a potential source for indirect transmission over large distances. Virus is present in considerable titres in tracheal mucus and in faeces in the acute and recovery phases of disease, respectively. Virus spreads horizontally by aerosol (inhalation) or ingestion of faeces or contaminated feed or water. The virus is highly infectious. Clinical signs will develop in contact chicks within 36 h and in nearby sheds within one to two days. Infection is resolved within fourteen days with a rise in antibody titres. In a small number of chicks, latent infection is established with subsequent erratic shedding of virus for a prolonged period of time via both faeces and aerosol. Movement of live birds should be considered as a potential source for the introduction of IBV. Isolation and identification of IBV is needed for positive diagnosis. The preferred method of isolation is to passage a sample in embryonating specified-pathogen-free chicken eggs. Identification is either by monoclonal antibody based enzyme-linked immunosorbent assay (ELISA) or polymerase chain reaction. Virus neutralisation test in tracheal organ culture is the best method for antigenic typing. Continual use of live vaccines complicates diagnosis since no simple diagnostic tool can differentiate a field from a vaccine strain. Nucleotide sequencing of the S1 glycoprotein is the only method to discriminate between all IBV strains. Serology is also complicated by continual use of live vaccines. For surveillance purposes, ELISA is the method of choice, regardless of the antigenic type of IBV involved. The assay is used to monitor the response to vaccination, but field challenge can only be detected if flock antibody status is monitored continually. The antigenic type of a challenge strain involved cannot be ascertained by ELISA.